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Identification of Novel GABAA Receptor Positive Allosteric Modulators with Novel Scaffolds via Multistep Virtual Screening
2024, 40(1): 230204  doi: 10.3866/PKU.WHXB202302044
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The GABAA receptor mainly mediates inhibitory signal transmission in mammalian central nervous systems and is the key target of sedative-hypnotics. However, the long-term use of sedative-hypnotics often leads to drug resistance, necessitating the development of novel sedative-hypnotics. This development can be achieved with novel scaffolds designed via the computer-aided drug design methods to obtain significant advantages. In this study, robust virtual screening models were established by identifying effective positive allosteric modulators of the GABAA receptor from ChEMBL and BindingDB databases. These compounds combined with randomly extracted negative compounds were firstly applied for a 10-fold cross validation and grid search to establish machine learning models which were subsequently evaluated in an independent test set. In this step, 4 machine learning methods and 6 fingerprints were used to establish 24 models. In the test set, the CDK_LR model performed the best (MCC = 0.751) and was used for subsequent virtual screening. Two effective molecular docking models were also established based on conformation 6D6T and 6D6U, wherein the root mean square deviation (RMSD) values of redocking experiments were 1.141 and 1.505 Å (1 Å = 0.1 nm), respectively. During the virtual screening, 41112 compounds from a commercial database were scanned by machine learning, molecular docking, and molecular mechanics-generalized Born surface area models. After the screening, 16 hits were obtained, 4 of which were structurally novel positive hits verified by whole-cell patch-clamp electrophysiology experiments. The compound GPR120 was verified experimentally at both the cell and animal levels. In cortical neurons recombinantly expressing α1β2γ2-type receptors, at 10 and 50 µmol∙L−1, GPR120 could potentiate GABA EC3-10 current by 71.5% and 163.8%, respectively. Total decomposition contribution analysis and point mutation experiment showed that the key binding site between GPR120 and the GABAA receptor is H102, similar to that of the positive drug Diazepam. To further verify GPR120 function at the animal level, locomotor activity and loss of righting reflex (LORR) tests were performed. GPR120 inhibited the locomotor activity of mice, which recovered after 6 h, indicating that GPR120 is a moderate sedative. In the pentobarbital sodium-induced righting reflex hour test, GPR120 (20 mg∙kg−1) significantly shortened the time to start LORR and prolonged its duration compared with the saline control group. In summary, using integrated virtual screening methods, GPR120 was identified as a moderate sedative with a novel scaffold.
Photo-Thermo Catalytic Oxidation of C3H8 and C3H6 over the WO3-TiO2 Supported Pt Single-Atom Catalyst
Ruijie Zhu, Leilei Kang, Lin Li, Xiaoli Pan, Hua Wang, Yang Su, Guangyi Li, Hongkui Cheng, Rengui Li, Xiao Yan Liu, Aiqin Wang
2024, 40(1): 230300  doi: 10.3866/PKU.WHXB202303003
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Catalytic oxidation is a commonly employed technology in the industry for removing volatile organic compounds (VOCs) due to its exceptional efficiency under mild operating conditions. Although supported Pt-based nano-catalysts are recognized widely as one of the most promising and extensively used industrial catalysts for VOC abatement, their practical application, and development are restricted by their exorbitant cost. Single-atom catalyst (SAC) with maximized metal utilization and exclusive electronic character has been explored extensively in various catalytic reactions. However, Pt SAC is usually deemed to be inactive in hydrocarbon oxidation reactions in thermal catalysis, compared with its nanoparticle counterpart. Here, we demonstrate that the WO3-TiO2 supported Pt SAC (Pt1/WO3-TiO2) exhibits much higher activities than the corresponding nanoparticle catalyst (PtNP/WO3-TiO2) in photo-thermo catalytic oxidation of C3H8 and C3H6, which represent different kinds of typical VOCs. A key finding is that the activities of Pt1/WO3-TiO2 and PtNP/WO3-TiO2 can be accelerated in photo-thermo catalytic C3H8 oxidation by overcoming oxygen poisoning. Upon the light irradiation, the apparent active energy (E a) of the Pt1/WO3-TiO2 and PtNP/WO3-TiO2 decline from 116 to 60 kJ·mol−1 and from 103 to 30 kJ·mol−1, respectively, substantiating their effectiveness in photo-thermo catalysis. Notably, a substantially higher reaction rate of 3792 μmol∙gPt −1∙s−1 on the Pt1/WO3-TiO2 is achieved, which should be a benchmark for C3H8 oxidation. More intriguingly, photo-thermo catalytic C3H6 oxidation on the PtNP/WO3-TiO2 is prohibited due to the strong adsorption-induced C3H6 poisoning on the Pt nanoparticles, for which the E a of the PtNP/WO3-TiO2 catalyst for C3H6 oxidation is maintained at approximately 55 kJ·mol−1, regardless of the light irradiation. In comparison, the C3H6 poisoning on the Pt1/WO3-TiO2 can be mitigated by light illumination, where the E a of the Pt1/WO3-TiO2 catalyst for C3H6 oxidation dramatically reduced from 49 to 16 kJ·mol−1, signifying that the high energy barrier of C3H6 oxidation can be mediated by the light. Profiting from the apt affinity between C3H6 and Pt single atoms, the photogenerated electrons accumulated on the Pt single atoms produce repulsive force towards the electron-rich C3H6 molecules, which is conducive to the C3H6 desorption from the Pt1/WO3-TiO2. Therefore, the Pt1/WO3-TiO2 exhibits enhanced activity in photo-thermo catalytic C3H6 oxidation. This study exemplifies that the advantages of SAC are not only saving the consumption of precious metals but also discovering new catalytic reactions on the account of the specific electronic characteristic.
Elastic and Thermoelectric Properties of Vacancy Ordered Double Perovskites A2BX6: A DFT Study
Muhammad Faizan, Guoqi Zhao, Tianxu Zhang, Xiaoyu Wang, Xin He, Lijun Zhang
2024, 40(1): 230300  doi: 10.3866/PKU.WHXB202303004
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The increasing global demand for energy and the detrimental effects of using fossil fuels highlight the urgent need for alternative and sustainable energy sources. Metal halide perovskites have gained significant research attention over the last few years, primarily for solar energy storage, light emission, and thermoelectrics, due to their low cost and high efficiency. To understand the thermoelectric transport characteristics of halide perovskites and improve their practical applications, precise knowledge of their heat transport mechanism is necessary. In this study, we used density functional theory (DFT) and different exchange-correlation functionals, namely the Perdew-Burke-Ernzerhof (PBE) and modified Becke Johnson (mBJ) schemes, to screen three inorganic halide perovskites, Rb2SnI6, Rb2PdI6, and Cs2PtI6, in their pristine forms for thermoelectric energy conversion. Here, we report the mechanical stability, effective masses, Seebeck coefficient, power factor, and thermoelectric figure of merit. Both PBE and mBJ functionals successfully determined the most stable geometry and accurate electronic structure for each halide perovskite. Initially, we optimized the crystal structures of all three compounds using the PBE functional and obtained the corresponding lattice parameters. The optimized lattice constants are in good agreement with the experimental values. We are the first to calculate the elastic constants and other mechanical parameters, such as the elastic moduli, Poisson's ratio, Pugh index, elastic anisotropy, and Grüneisen parameter, to determine the elastic and mechanical stability of these compounds. All three compounds (Rb2SnI6, Rb2PdI6, and Cs2PtI6) are mechanically stable and ductile. The effective mass of the electrons at the conduction band minimum was smaller than that of the holes at the valence band maximum. Electronic band structure calculations showed that all three compounds are narrow band gap semiconductors (with band gaps ranging from 0.47 to 1.22 eV) with degenerate band extrema. The low effective masses and favorable band gap feature make them ideal for thermoelectric applications. Our study reveals a high Seebeck coefficient of 0.76 mV·K−1 for Cs2PtI6 for hole doping at maximum temperature. Due to the high Seebeck coefficient and maximum power factor, we found high figure of merit (ZT) of 0.98 for Cs2PtI6, 0.96 for Rb2PdI6, and 0.97 for Rb2SnI6, upon p-type doping. With this study, we provide new insights into the thermoelectric performance of halide perovskites and can offer inspiration for the experimental synthesis of these compounds. Our results may also contribute to developing practical energy conversion and storage devices, which can significantly affect the renewable energy sector.
Microwave-Assisted Synthesis of Bismuth Chromate Crystals for Photogenerated Charge Separation
Chengbo Zhang, Xiaoping Tao, Wenchao Jiang, Junxue Guo, Pengfei Zhang, Can Li, Rengui Li
2024, 40(1): 230303  doi: 10.3866/PKU.WHXB202303034
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The conversion of renewable solar energy into chemical energy is an important topic in research. Recently, bismuth chromate (Bi2CrO6) has attracted attention in photocatalytic research, particularly for its potential applications in pollutant degradation and water splitting. This layered metal oxide exhibits a narrow optical band gap of approximately 1.9 eV and can utilize most of visible light in the solar spectrum. However, the photocatalytic activity of Bi2CrO6 is relatively low, and its poor charge separation properties restrict its practical applications. Herein, we report a microwave-assisted hydrothermal method for the fabrication of Bi2CrO6 crystals with high crystallinity and uniform morphology. Compared with the conventional preparations, microwave irradiation induces rapid volumetric heating and greatly accelerates nucleation and growth reactions, forming Bi2CrO6 crystals within minutes. Multiple characterization methods, including X-ray diffraction, Raman scattering, and scanning electron microscopy, were employed to examine the crystallinity and morphologies of the samples. Microwave-assisted synthesized Bi2CrO6 crystals showed better water oxidation activity in photocatalytic and photoelectrochemical tests than the conventional samples. Oxygen evolution rates were boosted 7.2 and 3.1 times using AgNO3 and Fe(NO3)3 as electron acceptors, respectively. Further investigations showed that microwave-assisted Bi2CrO6 crystals exhibited improved photogenerated charge separation. The average lifetime of photogenerated carriers, calculated from time-resolved photoluminescence results, also showed an increase. Furthermore, using photodeposition of metals and oxides as probes, the spatial separation of photogenerated electrons and holes was demonstrated to take place between {001} top and side facets of the Bi2CrO6 crystal samples. Loading reduction and oxidation cocatalysts onto different facets significantly enhanced the photocatalytic activities. These results enforce the promise of microwave-assisted Bi2CrO6 crystal synthesis for photocatalytic water-splitting applications and present a solution for efficient solar-energy conversion.
Mechanistic Insights into Water-Mediated CO2 Electrochemical Reduction Reactions on Cu@C2N Catalysts: A Theoretical Study
Hanyu Xu, Xuedan Song, Qing Zhang, Chang Yu, Jieshan Qiu
2024, 40(1): 230304  doi: 10.3866/PKU.WHXB202303040
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CO2 molecules can be converted into various fuels and industrial chemicals through electrochemical reduction, effectively addressing the problems of global warming, desertification, ocean acidification, and other adverse environmental changes and energy supply issues such as excessive utilization of nonrenewable fossil fuels. Generally, the pathway of the CO2 reduction reaction (CO2RR) involves multiple proton–electron pairs transferred to the reactants, resulting in the production of multiple reduction products. Here, protons are derived from water molecules under aqueous solvent conditions. Therefore, exploring the effect of water molecules on the proton–electron pair transfer process in CO2RRs is essential. In this study, we developed a water-mediated hydrogen shuttle model (H-shuttling) as a hydrogenation model to investigate the effect of water molecules on the proton–electron pair transfer process in CO2RRs and compared it with the widely used water-free direct hydrogenation model (H-transfer), wherein the hydrogen atom is used as a proton. Because copper is a metal electrode material capable of producing hydrocarbons from CO2 electroreduction with a high faraday efficiency, and nitrogen-doped graphene (C2N) exhibits excellent catalytic CO2 activation, we selected a single copper atom-embedded C2N (Cu@C2N) as the catalyst. Furthermore, to study the effect of graphene on the CO2RR activity of Cu@C2N/G, we selected a graphene-loaded Cu@C2N composite (Cu@C2N/G) as the catalyst because graphene was utilized as a substrate to boost the conductivity of the catalyst. In the two hydrogenation models, we investigated the mechanisms of CO2RRs on Cu@C2N and Cu@C2N/G catalysts through density functional theory calculations. Notably, in the H-shuttling model, the H atom combines with the water molecule to form H3O, which transfers one of its own H atoms to a reactant on the catalyst surface, yielding a reaction intermediate. The H-shuttling model enhances the interaction between the catalyst and intermediate. Graphene, as a substrate, transfers electrons to the Cu@C2N surface of the Cu@C2N/G catalyst, which is demonstrated by calculations of the Bader charge transferred between the reaction intermediate and catalyst, as well as the Gibbs free energy of the CO2 reduction elementary reaction. This effectively lowers the Gibbs free energy of the potential-determining step and enhances the CO2RR catalytic activity of Cu@C2N/G. Moreover the limiting potentials of the CO2RR and hydrogen evolution reaction are determined to obtain the activity and selectivity of the Cu@C2N and Cu@C2N/G catalysts. The results indicate that CO2 molecules on the Cu@C2N and Cu@C2N/G catalysts generate HCOOH at low applied potentials, and are able to produce CO, CH3OH, CH4, and H2 as the applied potentials increases.
Tungsten-Doped NiFe-Layered Double Hydroxides as Efficient Oxygen Evolution Catalysts
Xinxuan Duan, Marshet Getaye Sendeku, Daoming Zhang, Daojin Zhou, Lijun Xu, Xueqing Gao, Aibing Chen, Yun Kuang, Xiaoming Sun
2024, 40(1): 230305  doi: 10.3866/PKU.WHXB202303055
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Electrochemical water splitting proves critical to sustainable and clean hydrogen fuel production. However, the anodic water oxidation reaction—the major half-reaction in water splitting—has turned into a bottleneck due to the high energy barrier of the complex and sluggish four-electron transfer process. Nickel-iron layered double hydroxides (NiFe-LDHs) are regarded as promising non-noble metal electrocatalysts for oxygen evolution reaction (OER) catalysis in alkaline conditions. However, the electrocatalytic activity of NiFe-LDH requires improvement because of poor conductivity, a small number of exposed active sites, and weak adsorption of intermediates. As such, tremendous effort has been made to enhance the activity of NiFe-LDH, including introducing defects, doping, exfoliation to obtain single-layer structures, and constructing arrayed structures. In this study, researchers controllably doped NiFe-LDH with tungsten using a simple one-step alcohothermal method to afford nickel-iron-tungsten layered double hydroxides (NiFeW-LDHs). X-ray powder diffraction analysis was used to investigate the structure of NiFeW-LDH. The analysis revealed the presence of the primary diffraction peak corresponding to the perfectly hexagonal-phased NiFe-LDH, with no additional diffraction peaks observed, thereby ruling out the formation of tungsten-based nanoparticles. Furthermore, scanning electron microscopy (SEM) showed that the NiFeW-LDH nanosheets were approximately 500 nm in size and had a flower-like structure that consisted of interconnected nanosheets with smooth surfaces. Additionally, it was observed that NiFeW-LDH had a uniform distribution of Ni, Fe, and W throughout the nanosheets. X-ray photoelectron spectra (XPS) revealed the surface electronic structure of the NiFeW-LDH catalyst. It was determined that the oxidation state of W in NiFeW-LDH was +6 and that the XPS signal of Fe in NiFeW-LDH shifted to a higher oxidation state compared to NiFe-LDH. These results suggest electron redistribution between Fe and W. Simultaneously, the peak area of surface-adsorbed OH increased significantly after W doping, suggesting enhanced OH adsorption on the surface of NiFeW-LDH. Furthermore, density functional theory (DFT) calculations indicated that W(Ⅵ) facilitates the adsorption of H2O and O*-intermediates and enhances the activity of Fe sites, which aligns with experimental results. The novel NiFeW-LDH catalyst displayed a low overpotential of 199 and 237 mV at 10 and 100 mA∙cm−2 in 1 mol∙L−1 KOH, outperforming most NiFe-based colloid catalysts. Furthermore, experimental characterizations and DFT+U calculations suggest that W doping plays an important role through strong electronic interactions with Fe and facilitating the adsorption of important O-containing intermediates.
In situ and Ex situ Investigation of the Organic-Organic Interface Effect
Lianlian Ji, Xianpeng Wang, Yingying Zhang, Xueli Shen, Di Xue, Lu Wang, Zi Wang, Wenchong Wang, Lizhen Huang, Lifeng Chi
2024, 40(1): 230400  doi: 10.3866/PKU.WHXB202304002
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Organic-organic heterostructures have been widely applied in various organic electronic devices, including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells. A thorough understanding of the interface effect in these heterostructures is of crucial importance for device design and optimization. However, owing to the diverse chemical properties and weak van der Waals interactions of organic semiconductors, interface charge transport is critically related to the organic-organic electronic structure and environmental atmosphere. Therefore, an in situ real-time investigation of the electrical properties in vacuum could efficiently avoid atmospheric influence and aid determination of the instinct interactions at the organic-organic interface. Herein, we report in situ real-time electrical property monitoring of the pentacene/vanadyl phthalocyanine (VOPc) heterostructure with top layer pentacene growth. The hole mobility of the heterostructure transistors decreases from 0.4 cm2∙V−1∙s−1 to approximately 0.2 cm2∙V−1∙s−1, while the electron mobility increases rapidly from 0.01 cm2∙V−1∙s−1 to approximately 0.9 cm2∙V−1∙s−1 as the pentacene thickness increases. This enhanced electron transport is attributed to the interface electron transfer from pentacene to VOPc, leading to filling of trap states in the VOPc layer and an improvement in the charge mobility and n-channel current. In contrast, the ex situ processing results indicate that atmospheric exposure will significantly suppress this charge transfer effect, resulting to a negligible improvement in the electron transport. The film morphology, Kelvin probe force microscopy, and X-ray photoelectron spectroscopy characterizations suggest electron transfer occurs from pentacene to VOPc. Additionally, density functional theory (DFT) calculations confirm that the interaction between pentacene and VOPc is strong and the pentacene molecule tends to transfer electrons to VOPc with a calculated charge transfer value of approximately 0.15 e. Moreover, this interface charge transfer is significantly suppressed with the presence of either O2 or H2O, which is highly consistent with our experiment results. In this paper, we provide a clear understanding of the instinct organic-organic interface charge transfer effect by using in situ characterization, which will be helpful for further device performance optimization and analysis.
Identification of Charge Transfer Pathways in Metal-Organic Framework- Derived Ni-CNT/ZnIn2S4 Heterojunctions for Photocatalytic Hydrogen Evolution
Kezhen Lai, Fengyan Li, Ning Li, Yangqin Gao, Lei Ge
2024, 40(1): 230401  doi: 10.3866/PKU.WHXB202304018
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Hydrogen is an important zero-pollution green energy source with potential for alleviating environmental contamination and energy shortages. Hydrogen evolution via solar-energy-induced semiconducting water splitting is among the most environmentally friendly methods available to date. In this study, a metal–organic-framework-derived, Ni-decorated carbon nanotube (Ni-CNT) is used as a non-noble co-catalyst. This Ni-CNT is grown in situ on ZnIn2S4 nanosheets using a simple one-step oil bath strategy, wherein Ni nanoparticles are wrapped around the top and cross sections of the nanotubes, preventing their agglomeration. Notably, Ni-CNT/ZnIn2S4 heterostructures feature intimate contact interfaces that promote charge transfer, facilitating their use as efficient photocatalysts for hydrogen evolution. The 38Ni-CNT/ZnIn2S4 sample exhibits a high H2 production rate (12267 μmol·h−1·g−1), with an apparent quantum efficiency (AQE) of 11.3% under 420 nm monochromatic light irradiation, which is nearly 6.4 times that of pure ZnIn2S4. The results of X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) corroborate the observations on Ni-CNT/ZnIn2S4 heterostructures. Electrochemical measurements reveal that the combination of the Ni-CNT and ZnIn2S4 facilitates the transfer of photogenerated electrons and effectively prevents rapid recombination of photocarriers, thus improving the hydrogen evolution performance of ZnIn2S4. Electron spin resonance (ESR) results further prove that co-catalyst Ni-CNTs are beneficial for prolonging the lifetimes of ZnIn2S4 photogenerated electrons, thereby achieving effective charge separation. A charge transfer pathway in the heterojunction interfaces is further explored and confirmed by density functional theory (DFT) calculations. The difference in the Fermi level energy (E f) contributes to both charge migration and the generation of a built-in electronic field (BEF), indicating that the energy band of ZnIn2S4 bends downward, which is favorable for photogenerated electron flow from ZnIn2S4 to the Ni-CNT electron acceptor. The results of planar-averaged electron density difference analysis confirm that the hot electrons are transferred from Ni nanoparticles to the CNT and then to the ZnIn2S4 nanosheets, indicating the formation of a photogenerated electron transfer pathway of ZnIn2S4 → CNT → Ni. Furthermore, Gibbs free energy of H* adsorption (ΔG H*) and crystal orbital Hamilton population (COHP) analysis indicate that Ni nanoparticles can serve as active sites, promoting H2 evolution. Thus, the present study formulates a new strategy for developing low-cost, high-efficiency, non-noble-metal co-catalysts for photocatalytic hydrogen production.
Effects of Electron Density Variation of Active Sites in CO2 Activation and Photoreduction: A Review
Yuehan Cao, Rui Guo, Minzhi Ma, Zeai Huang, Ying Zhou
2024, 40(1): 230302  doi: 10.3866/PKU.WHXB202303029
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Photocatalytic reduction of CO2 into value-added chemicals is a feasible approach to harvest solar light energy and storing energy in the form of chemical fuels as well as to mitigate the effects of global climate change and help achieve an artificial carbon cycle. However, the efficiency of CO2 photoreduction is low for commercial purposes. This is mainly due to the difficult adsorption and activation process of CO2 molecules, the unsatisfactory selectivity of target products, and the uncontrolled-subsequent reaction process of the generated carbon products. CO2 photoreduction requires substantial electrons for participation. Hence, these issues are due to the electron density modulation of the active sites of catalysts. Unfortunately, the CO2 photoreduction process involves multi-fundamental steps, which leads to different requirements in electron density modulation. The performance might not be effectively improved by directly enhancing or weakening the total electron density of active sites. In this paper, we summarize recent advances in the influence of electron density variation of the active sites in strengthening the adsorption and activation of CO2 molecules, enhancing the selectivity of target carbon products and modulating the subsequent reaction process of the generated carbon products. This review begins with the effect of different types of active sites in strengthening the adsorption and activation of the CO2 molecules and the related methods for modulating the electron density of active sites. Active sites with high electron densities can significantly enhance the adsorption and activation of CO2. Introducing metal and fabricating the defects on catalyst surfaces are effective strategies for fabricating the electron-rich active sites. After that, we discuss the influence of electron density variation in enhancing the selectivity of target carbon products in detail. In this part, the related effects in the multielectron donation from the catalyst surface, the reactive intermediates, and the competition hydrogen evolution reaction are summarized. Enhancing the electron density of active sites strengthens the former two processes. For multielectron donation, introducing cocatalysts or fabricating heterostructures are the most effective methods for enhancing the electron density of active sites. The adsorption and conversion process of intermediates are mainly affected by the accumulation sites of electrons. The active sites with low coordination are more favorable to achieving the generation of multi-electronic carbon products. In contrast, the hydrogen evolution reaction is significantly inhibited by reducing the electron density of active sites. Moreover, elemental doping is considered one of the most effective strategies. Finally, we describe the method for weakening the electron density of active sites to promote product desorption and inhibit the photooxidation of reactive products.
Silicon Nanostructure Arrays: An Emerging Platform for Photothermal CO2 Catalysis
Chengcheng Zhang, Zhiyi Wu, Jiahui Shen, Le He, Wei Sun
2024, 40(1): 230400  doi: 10.3866/PKU.WHXB202304004
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Rapid population growth and the demand for energy, which is powered by unrestricted fossil fuel exploitation, have caused severe environmental problems. Thus, it is crucial to effectively exploit alternative clean energy sources. Solar energy, which is a sustainable renewable energy source, provides an effective strategy for mitigating the energy crisis and greenhouse effect without resulting in additional carbon emissions. The concept of converting carbon dioxide (CO2) into synthetic fuels is a promising solution towards realizing a sustainable carbon-neutral economy. Photocatalysis is a favorable approach for CO2 conversion, but it has limitations in terms of conversion rates, efficiency, and scalability. Therefore, the novel concept of photothermal catalysis has been proposed based on the photothermal effect of catalysts, which allows for the complete exploitation of the solar spectrum, especially infrared light that is typically wasted during photochemical catalysis. Photothermal catalysis, combining photochemical and photothermal effects, can effectively catalyze chemical reactions under mild conditions. Although various metal structures can serve as the light-absorbing and active centers for photothermal catalysis, they suffer from disadvantages such as insufficient light utilization, high cost, and poor stability. Recently, naturally abundant silicon has emerged as a prospective photothermal catalyst, especially silicon nanostructure arrays, which outperform other conventional silicon materials owing to their excellent light-harvesting ability and efficient catalytic performance. Compared with conventional photothermal catalysts, silicon nanostructure arrays have demonstrated unique catalytic performance advantages in the photothermal CO2 reduction reaction. As a platform, silicon nanostructure arrays exhibit an excellent light-harvesting ability, high specific surface area, and versatile hybridization possibilities. This review discusses the fundamental concepts and principles related to the theory and applications of photothermal catalytic CO2 conversion, the functionalities of silicon nanostructure arrays in conventional photothermal CO2 catalytic reduction, and the recent developments in photothermal CO2 catalysis using silicon nanostructure arrays. Ultimately, it provides a guide for the development direction of high-performance nanostructure arrays-based photothermal CO2 catalysts.
霍春安, 邱圣杰, 梁青满, 耿碧君, 雷志超, 王干, 邹玉玲, 田中群, 杨扬
2024, 40(1): 230303  doi: 10.3866/PKU.WHXB202303037
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光镊技术能够实现对介观乃至微观颗粒的稳定捕获和灵活操控,是对微纳物体和单个分子施加力并观测其响应的理想操控手段。受限于光的衍射极限,传统光镊难以实现对100 nm以下物体的捕获和操控。研究者们通过开发特殊的材料和结构,将它们与传统光镊技术结合,不断突破其在小尺度物体的捕获和操控极限。本文主要综述了近年来光镊的不同技术路线在突破捕获操控极限的研究进展,以及其在物理化学领域中的应用,并对其发展和应用进行展望。
王鹤然, 陈凯, 伏硕, 王晧暄, 袁加轩, 胡星奕, 许文娟, 密保秀
2024, 40(1): 230304  doi: 10.3866/PKU.WHXB202303047
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吩噻嗪及其衍生物材料是一类重要的多环芳烃材料,在光电子领域有着广泛的应用。其中,基于苯并噻嗪材料的研究相对较少。在本文中,我们分别在吩噻嗪的1, 2-、2, 3-和3, 4-位引入苯基,制备了三种同分异构的双苯并吩噻嗪化合物D-PTZa、D-PTZb和D-PTZc,研究了它们的构效关系,并与双吩噻嗪化合物(D-PTZ)进行了对比。研究发现,D-PTZb和D-PTZc的HOMO和LUMO分布与D-PTZ的类似;对于D-PTZa,其1, 2-位引入的苯基与中间的苯环空间张力较大,造成空间结构极度扭曲,性质比较特殊。并苯的引入可以有效增加分子的共轭长度,使得最大吸收波长发生红移;在2, 3-位引入苯基可以有效地稳定HOMO能级,使基于ππ*跃迁的能隙稍有增大,呈现蓝光发射,溶液的荧光量子产率为1.7%;而在3, 4-位引入苯基使LUMO分布更加趋向于线型,从而使LUMO更加稳定,使基于ππ*跃迁的能隙降低,其最大发射峰位于520 nm处,呈现黄绿光发射,溶液荧光量子产率为13%。此外并入苯环之后,空间张力增大,化合物的分解温度降低。我们的分子设计和结构–性质关系的研究可以为设计新的吩噻嗪材料提供基础指导。
BaTiO3基超薄层BME MLCC的可靠性机理
朱超琼, 蔡子明, 冯培忠, 张伟晨, 惠可臻, 曹秀华, 付振晓, 王晓慧
2024, 40(1): 230401  doi: 10.3866/PKU.WHXB202304015
[摘要]  (148) [HTML全文] (148) [PDF 2391KB] (18)
多层陶瓷电容器(Multilayer ceramic capacitors,MLCC)作为市场占有率最高的无源电子元器件,是基础电子元件产业中需要突破关键技术的重点产品之一,在汽车电子、5G通讯、电网调频、航空航天等领域有广泛的应用。在小型化、薄层化发展趋势下,MLCC的介质层厚度不断降低,单层介质在相同电压下的电场显著增大,尤其是中高压超薄层MLCC。因此,MLCC的可靠性愈发成为一项关键的产品质量指标。本文结合加速老化测试、高温阻抗谱、漏电流测试,系统研究超薄层MLCC的劣化机理,揭示抑制氧空位的迁移与富集是保证超薄层MLCC可靠性的重中之重。为此,应减小介质层内部的氧空位浓度,增大其迁移所需的激活能,提高界面肖特基势垒,从而提升超薄层MLCC的可靠性。本文的研究成果为超薄层MLCC介质材料的设计提供了有力指导。

Performance Improvement and Antibacterial Mechanism of BiOI/ZnO Nanocomposites as Antibacterial Agent under Visible Light
Jing Kong, Jingui Zhang, Sufen Zhang, Juqun Xi, Ming Shen
2023, 39(12): 221203  doi: 10.3866/PKU.WHXB202212039
[摘要]  (169) [HTML全文] (169) [PDF 3678KB] (169)
Bacterial infections cause various serious diseases including tuberculosis, meningitis, and cellulitis. Moreover, there is an increase in the number of drug-resistant bacterial strains, which has caused a global health issue. Thus, it is highly essential to develop more effective antibacterial agents. Currently, zinc oxide (ZnO) is commonly used as an inorganic antibacterial agent, but with a notable limit in efficiency. In this work, to improve ZnO antibacterial activity under visible light, bismuth oxyiodide (BiOI) with a narrow bandgap of 1.8 eV was used as a suitable refinement to ZnO. Four different BiOI/ZnO nanocomposites were designed and synthesized via a simple mechanical stirring method in an atmospheric environment; these were denoted as BiOI/ZnO-2.5%, BiOI/ZnO-5%, BiOI/ZnO-10%, and BiOI/ZnO-20%. The successful synthesis of the BiOI/ZnO nanocomposites was verified through X-ray powder diffraction, energy-dispersive X-ray analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). A unique BiOI/ZnO heterojunction was also observed for the nanocomposites through high-resolution TEM, XPS, and selected area electron diffraction. Ultraviolet-visible diffuse reflectance spectroscopy revealed that all four BiOI/ZnO nanocomposites exhibited improved visible light absorption and possessed narrower bandgaps than the ZnO nanoparticles (nano-ZnO). Furthermore, the antibacterial activities of all BiOI/ZnO nanocomposites were investigated under visible light against both gram-positive and gram-negative bacteria strains. The results indicated a significant improvement in the antibacterial activities of BiOI/ZnO-10% and BiOI/ZnO-20% against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Strong light exposure was found to be attributable to an increase in the antibacterial activity against S. aureus. In addition, the antibacterial mechanistic investigation was conducted upon visible light activation. The SEM images showed completely broken bacterial cell walls for both bacteria strains after treatment with the BiOI/ZnO nanocomposites. Hydroxyl radicals (•OH), which are strong reactive oxygen species, generated by the BiOI/ZnO nanocomposites under visible light, were also trapped by 5,5-dimethyl-1-pyrroline-N-oxide. Furthermore, zeta potential analysis revealed the presence of more positively charged BiOI/ZnO nanocomposite surfaces than the surfaces of nano-ZnO. The metal ions released from the BiOI/ZnO nanocomposites under visible light were also studied through inductively coupled plasma mass spectrometry. Based on the above results, BiOI/ZnO nanocomposites were found to exhibit antibacterial mechanism similar to that of nano-ZnO. In the dark, E. coli growth was only inhibited by Zn2+ released from both BiOI/ZnO nanocomposites and pure nano-ZnO. After visible light activation, •OH generated from the BiOI/ZnO nanocomposites mainly contributed to the bacterial cell death of both E. coli and S. aureus. This study proposes an effective strategy to enhance the antibacterial activity of nano-ZnO under visible light upon the formation of nanocomposites with BiOI. Besides, this study indicates that the ZnO-based nanocomposites can be used as a more effective antibacterial agent in clinical applications.
Introducing Novel, Multiple Cd Coordination Modes into Gold Nanoclusters by Combined Doping for Enhancing Electrocatalytic Performance
Zhen Liu, Xiangfu Meng, Wanmiao Gu, Jun Zha, Nan Yan, Qing You, Nan Xia, Hui Wang, Zhikun Wu
2023, 39(12): 221206  doi: 10.3866/PKU.WHXB202212064
[摘要]  (125) [HTML全文] (125) [PDF 2578KB] (125)
In recent years, gold nanoclusters have been widely used in catalysis, and alloying has become one of the most important methods for improving the catalytic performance of gold nanoclusters. As for the electrocatalytic reduction of CO2 (CO2RR), although many gold nanoclusters show fairly good Faraday efficiencies through Cd-doping, they still exhibit low current density. Furthermore, as an increasing number of Au-Cd alloy nanoclusters are reported, there is a growing interest in understanding the correlation between Cd coordination and catalysis performance. In most cases, Cd atoms are typically doped in the outer staples and connect with Au atoms through S coordinations. Are there any other unreported Cd coordination modes? Can novel or numerous Cd coordination modes be introduced into gold nanoclusters to increase the current density in the CO2RR? This study investigates these questions.Inspired by our previous work on surface sulfur doping, we employed a combined doping (S + Cd doping) strategy, developed a two-step synthesis method, and successfully synthesized a novel Au-Cd nanocluster—Au41Cd6S2(SCH2Ph)33. Precise formula and structure were determined by electrospray ionization mass spectrometry (ESI-MS), thermalgravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray crystallography (SCXC). SCXC shows that the nanocluster contains a biicosahedral Au23 kernel, and all the Cd atoms are doped in the outer staples, providing a variety of coordination environments for Cd atoms. In addition to two common Au3(SR)4 trimers in the outer staples, two unusual Au5Cd2(SR)9S long staples were discovered cross-covering the top of the kernel, and a (S-Au-S)2(CdS-S-CdS) tetramer staple with two Cd atoms directly linked through S was also discovered for the first time. This alloy cluster shows robust stability in both high-temperature and oxidation environments. Compared with the "homo-kernel-hetero-staples" nanocluster Au38(SCH2Ph)24, Au41Cd6S2(SCH2Ph)33 exhibits distinct UV-Vis/NIR absorption and differential pulse voltammetry (DPV) results, indicating that the differences in the outer staples have a significant effect on the optical and electronic properties of gold nanoclusters. When used as an electrocatalyst, the Au41Cd6S2(SCH2Ph)33 exhibits a higher Faradaic efficiency for the CO2RR (99.3% at −0.7 V) and a higher CO partial current density (120 mA∙cm−2 at −0.9 V) than Au38(SCH2Ph)24, providing an ideal platform for investigating the roles of different Cd coordination modes in outer staples on CO2RR. DFT calculations interpret the experimental finding that Cd doping improves the catalytic performance and reveal that the Cd-Cd site is the most active site and the Au-Cd site furthest away from the kernel is the best-performing catalytic site given the consideration of both selectivity and activity.This work introduces a novel strategy to enhance the catalytic performance of gold nanoclusters, having important implications for future research on the syntheses and structural properties of metal nanoclusters, and is expected to inspire more work in related areas.
Electronic Modulation of Ni-Mo-O Porous Nanorods by Co Doping for Selective Oxidation of 5-Hydroxymethylfurfural Coupled with Hydrogen Evolution
Shuyi Zheng, Jia Wu, Ke Wang, Mengchen Hu, Huan Wen, Shibin Yin
2023, 39(12): 230103  doi: 10.3866/PKU.WHXB202301032
[摘要]  (166) [HTML全文] (166) [PDF 4776KB] (166)
Fossil fuel depletion and environmental deterioration have created an urgent need to develop renewable and clean energy. Biomass, a sustainable organic carbon source, can meet the huge demand for energy and chemicals. Among them, 5-hydroxymethylfurfural (HMF) is an important biomass-derived platform molecule, which can be converted into various high-value chemicals. One of its oxidation products, 2,5-furandicarboxylic acid (FDCA), is expected to replace terephthalic acid as a raw material for the synthesis of bio-based degradable plastics. The electrooxidation of HMF emerges as a promising green route for preparing FDCA due to its advantages of mild conditions, fast reaction rate, and high selectivity. The theoretical potential of the HMF electrooxidation reaction (HMFOR, 0.3 V vs. reversible hydrogen electrode, RHE) is also lower than that of the oxygen evolution reaction (OER, 1.23 V vs. RHE). Coupling anodic HMFOR with cathodic hydrogen evolution reaction (HER) is expected to simultaneously produce valuable FDCA and reduce the cell voltage of hydrogen (H2) evolution. However, the construction of efficient and stable bifunctional catalysts for HMFOR-assisted H2 production is still challenging. In this study, Co-doped Ni-Mo-O porous nanorods grown on a nickel foam (Co-NiMoO/NF) is prepared by simple hydrothermal and calcination methods for both HMFOR and HER. Results of electrocatalytic studies indicate that Co-NiMoO/NF exhibits enhanced performance for HMFOR (E 10/100 = 1.31/1.37 V vs. RHE) and HER (E −10/−100 = −35/−123 mV vs. RHE) and shows durable HMFOR/HER stability. In particular, Co-NiMoO/NF maintains high FDCA selectivity (~99.2%) and Faradaic efficiency (~95.7%) for 40 successive cycles at 1.36 V vs. RHE for HMFOR. Conversely, Co-NiMoO/NF maintains stable operation at −200 mA∙cm−2 for 50 h with no significant activity attenuation for HER. When coupled as a bifunctional electrode for overall HMF splitting, Co-NiMoO/NF reaches an electric flux of 50 mA∙cm−2 at 1.48 V, which is 290 mV lower than that of the overall water splitting. This confirms that the HMFOR-assisted H2 production over Co-NiMoO/NF significantly reduces the energy consumption. Moreover, the two-electrode system maintains good FDCA selectivity (97.6%) for 10 cycles at 1.45 V, implying good stability of HMFOR-assisted H2 evolution. The remarkable catalytic performance of Co-NiMoO/NF could be due to the introduction of Co, which optimizes the electronic structure of Ni-Mo-O and adsorption behaviors of the reactants, thereby enhancing the intrinsic activity and stability of the catalyst. Meanwhile, the porous nanorod structure enhanced the mass transport of substrates and desorption of bubbles, thereby elevating the HMFOR/HER kinetics. This study provides useful insights for designing efficient and durable bifunctional catalysts for HMFOR and HER.
Pickering Emulsion Templated Proteinaceous Microsphere with Bio-Stimuli Responsiveness
Weijie Jiang, Hang Jiang, Wei Liu, Xin Guan, Yunxing Li, Cheng Yang, To Ngai
2023, 39(12): 230104  doi: 10.3866/PKU.WHXB202301041
[摘要]  (120) [HTML全文] (120) [PDF 14028KB] (120)
Bio-stimuli-responsive microspheres, which can encapsulate and release actives in response to physiological triggers, have attracted increasing attention in pharmaceutical, cosmetic, food biotechnology, and agricultural industries. However, most microspheres are based on synthetic polymers and suffer from a lack of biocompatibility due to the residues of harsh organic solvents or crosslinkers used in the synthesis process. Herein, we develop a simple and sustainable method for the construction of proteinaceous microspheres templated from Pickering double emulsions. Specifically, silica nanoparticles with a diameter of 100 nm were synthesized by Stöber method and modified by reacting with dichlorodimethylsilane. The Pickering emulsions are stabilized by hydrophobic silica nanoparticles, while zein protein is dissolved in the middle phase. Subsequent ethanol removal from the emulsion template precipitated the protein skeleton. First, we stained the aqueous ethanol phase with rhodamine B and the oil phase with pyrene to demonstrate the formation of double emulsions by confocal laser scanning microscopy (CLSM). The morphology of microspheres and silica nanoparticles was characterized by scanning electron microscopy (SEM). The obtained microspheres showed high sphericity and uniformity. In addition to acting as particulate stabilizers, the silica nanoparticles could improve the mechanical strength and monodispersity of microspheres. Herein, fluorescein isothiocyanate (FITC)-labeled dextran was chosen as the model active for encapsulation into microspheres. The CLSM images showed that it was uniformly dispersed in the microspheres and had no effect on the structure of the microspheres. Next, we investigated the pH tolerance of the microspheres. Through optical microscope, it was noted that the structure was intact under pH 3–11, and thus, it has a high resistance. Finally, we investigated the bio-stimuli-responsive behavior of microspheres. Zein is rich in sulfur-containing amino acids, which can form intra- and inter-molecular disulfide bonds. Because disulfide bonds can be reduced by glutathione (GSH) and the protein itself has enzymatic hydrolysis characteristics, the proteinaceous microspheres can be triggered release in response to GSH and protease. The release profiles of FITC-dextran from microspheres at different concentrations of GSH and protease were evaluated by fluorescence spectrophotometer. The decomposition behavior of microspheres under certain concentrations of GSH and protease was further verified by CLSM and SEM. To conclude, excellent stability and tunability of emulsion templates render the resulting proteinaceous microspheres with adjustable structures. Meanwhile, the proteinaceous microspheres have high encapsulation efficiency of model actives and have shown excellent bio-stimuli-responsiveness to protease and glutathione.
Construction of a Highly Active Rh/CeO2-ZrO2-Al2O3 Catalyst Based on Rh Micro-Chemical State Regulation and Its Three-Way Catalytic Activity
Jialin Mou, Liuling Chen, Jun Fan, Lu Zeng, Xue Jiang, Yi Jiao, Jianli Wang, Yaoqiang Chen
2023, 39(12): 230204  doi: 10.3866/PKU.WHXB202302041
[摘要]  (150) [HTML全文] (150) [PDF 3358KB] (150)
With the increasing number of automobile vehicles, the exhaust emitted poses a severe menace to the environment and human health, necessitating the purification of exhaust pollutants. Meanwhile, the high price of noble metals and their limited supply require a decrease in noble metal loading to reduce the costs of three-way catalysts (TWCs). Therefore, improving the utilization efficiency of noble metals and their catalytic behavior is critical for the development of next-generation TWCs with low noble metal loading. Herein, the Rh micro-chemical state was modulated using the liquid-phase reduction method combined with atmospheric heat treatment to enhance the catalytic behavior of Rh-based catalysts with low Rh loading. The catalyst was characterized using X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), CO chemisorption, X-ray photoelectron spectroscopy (XPS), the FTIR spectroscopy of chemisorbed CO (CO-FTIR), transmission electron microscopy (TEM), and in situ diffuse reflectance IR (in-situ DRIFTS) to illustrate the relationship between Rh micro-chemical state (including valence state ratio and dispersion) and catalytic activity. The as-prepared catalyst re-Rh/CeO2-ZrO2-Al2O3-H2 (re-Rh/CZA-H2) exhibited better catalytic activity and a wider air/fuel ratio (λ) operating window with T 90 values 30–73 ℃ and 51–86 ℃ lower than those of the catalysts synthesized by liquid-phase reduction and traditional impregnation method, respectively. In addition, aged samples prepared by the combined scheme also exhibited excellent activity and stability, where the T 50 and T 90 values were lower than the fresh catalyst. Structure-activity relationship results demonstrated that the better catalytic activity of re-Rh/CZA-H2 could be attributed to the optimal valence state ratio and highly dispersed Rh species, which increased the number of effective active sites. The considerable stability was attributed to the stable structure of the CeO2-ZrO2-Al2O3 (CZA) support, improved dispersion, and the high contents of active Rh species, which exposed more active sites to promote reactant conversion. In addition, the synergistic effect between the metallic Rh and oxygen vacancies could facilitate the anchoring of Rh nanoparticles to inhibit Rh sintering. Therefore, adjusting the micro-chemical state of noble metals by the combinatorial scheme developed herein provides a novel route for improving the catalytic activity, high-temperature stability, and air/fuel operating window of these catalysts.
2D/3D S-Scheme Heterojunction Interface of CeO2-Cu2O Promotes Ordered Charge Transfer for Efficient Photocatalytic Hydrogen Evolution
Lijun Zhang, Youlin Wu, Noritatsu Tsubaki, Zhiliang Jin
2023, 39(12): 230205  doi: 10.3866/PKU.WHXB202302051
[摘要]  (193) [HTML全文] (193) [PDF 12292KB] (193)
Rapid intrinsic carrier recombination severely restricts the photocatalytic activity of CeO2-based catalytic materials. In this study, a heterogeneous interfacial engineering strategy is proposed to rationally perform interface modulation. A 2D/3D S-scheme heterojunction with strong electronic interactions was constructed. A composite photocatalyst was synthesized for the 3D Cu2O particles anchored at the edge of 2D CeO2. First-principles calculations (based on density functional theory) and the experimental results show that a strongly coupled S-scheme heterojunction electron transport interface is formed between CeO2 and Cu2O, resulting in efficient carrier separation and transfer. The photocatalytic hydrogen evolution activity of the composite catalyst is significantly improved in the system with triethanolamine as the sacrificial agent and is 48 times as that of CeO2. In addition, the resulting CeO2-Cu2O photocatalyst affords highly stable photocatalytic hydrogen activity. This provides a general technique for constructing unique interfaces in novel nanocomposite structures.
RuP Nanoparticles Anchored on N-doped Graphene Aerogels for Hydrazine Oxidation-Boosted Hydrogen Production
Zheng-Min Wang, Qing-Ling Hong, Xiao-Hui Wang, Hao Huang, Yu Chen, Shu-Ni Li
2023, 39(12): 230302  doi: 10.3866/PKU.WHXB202303028
[摘要]  (135) [HTML全文] (135) [PDF 2266KB] (135)
'Green hydrogen' is a promising clean energy carrier for use instead of traditional fuels. For obtaining 'green hydrogen', electrochemical water splitting has been receiving considerable attention due to its eco-friendly and low-cost properties. However, the sluggish kinetics of the anodic oxygen evolution reaction (OER) reduces the efficiency of hydrogen production. Accordingly, the hydrazine oxidation reaction (HzOR) with low theoretical potential (−0.33 V vs. RHE) has been proposed as a reasonable alternative for the OER. In this study, graphene aerogel (GA) was utilized as a conductive substrate with a 3D porous framework. Ru-polyethyleneimine (Ru-PEI) complexes were adsorbed on the GA surface. Phytic acid (PA) was further adsorbed to form Ru-PEI-GA-PA hybrids through the hydrogen bond interaction between PA and PEI, which can serve as a precursor to synthesize RuP nanoparticles anchored on N-doped GA (RuP/N-GA) through the phosphorization reaction. In the pyrolysis process, the ultra-small RuP was formed at the GA surface. Additionally, the decomposition of PEI and PA can introduce abundant N and P heteroatoms into the structure of GA. As a result, RuP/N-GA hybrids achieve efficient HzOR with a low working potential of −54 mV at 10 mA∙cm−2. Moreover, the novel RuP/N-GA hybrids with low Ru loading also exhibit a promising hydrogen evolution reaction (HER) activity with an overpotential of −19.6 mV at 10 mA∙cm−2. Among various RuP/N-GA hybrids, the Tafel plot of HER at RuP/N-GA-900 reveals the smallest value to be 37.03 mV∙dec−1, which affords the fastest HER kinetics. Meanwhile, the result suggests that the HER at RuP/N-GA-900 undergoes a Heyrovsky mechanism similar to that of Pt. The theoretical results revealed that the anchored structure and the presence of N heteroatoms can promote the HzOR on RuP nanoparticles. The free energy of hydrazine molecular adsorption on RuP/N-GA was −0.68 eV, indicating that N-doping in the RuP/N-GA structure can adjust the electronic structure of the Ru active site, which also contributes to the enhanced HzOR activity of the Ru site. Additionally, RuP/N-GA hybrids exhibited excellent cycling and long-term stability for both HER and HzOR, superior to those of commercial Pt/C. Based on the bifunctional activity of RuP/N-GA hybrids, the constructed two-electrode hydrazine split system exhibits an extremely low cell voltage of 41 mV at 10 mA∙cm−2 for the hydrogen production, which achieves the goal of energy-saved hydrogen production at low voltage. The excellent electrocatalytic activity of RuP/N-GA hybrids is attributed to the ultrasmall RuP nanoparticles for abundant Ru active sites. Meanwhile, the synergistic effect between N-doping in GA frameworks with RuP nanoparticles contributes to the activity enhancement of RuP/N-GA hybrids, in which the 3D porous N-GA with few-layer morphology accelerates the electron and mass transfer and the electron interaction between N-GA and RuP nanoparticles promotes the electrocatalytic activity of RuP nanoparticles for both HER and HzOR. This study extends the bifunctional electrocatalyst for the HER and HzOR to achieve energy-saved hydrogen production and sheds new light on the design and synthesis of advanced electrocatalysts via the adsorption-phosphatization method.
王匡宇, 刘凯, 伍晖
2023, 39(12): 230100  doi: 10.3866/PKU.WHXB202301009
[摘要]  (148) [HTML全文] (148) [PDF 3140KB] (148)
彭芦苇, 张杨, 何瑞楠, 徐能能, 乔锦丽
2023, 39(12): 230203  doi: 10.3866/PKU.WHXB202302037
[摘要]  (225) [HTML全文] (225) [PDF 4938KB] (225)
李景学, 于跃, 徐斯然, 闫文付, 木士春, 张佳楠
2023, 39(12): 230204  doi: 10.3866/PKU.WHXB202302049
[摘要]  (472) [HTML全文] (472) [PDF 4739KB] (472)
张涛, 龚思敏, 陈平, 陈琪, 陈立桅
2023, 39(12): 230102  doi: 10.3866/PKU.WHXB202301024
[摘要]  (146) [HTML全文] (146) [PDF 3743KB] (146)
准二维钙钛矿由于具有较大的激子结合能和高效的能量转移等优势,在发光二极管(light-emitting diodes,LED)中的应用前景被广泛看好。然而,准二维钙钛矿溶液加工成膜过程中易形成大量的低维相和表界面缺陷,引起严重的非辐射复合,成为限制发光二极管器件性能的瓶颈。在本工作中,通过在PEA2Cs2Pb3Br10钙钛矿前驱体中加入1, 6-二(丙烯酰氧基)-2, 2, 3, 3, 4, 4, 5, 5-八氟己烷(OFHDODA)小分子添加剂,将钙钛矿薄膜的荧光量子效率(Photoluminescence Quantum Yield,PLQY)从19.7%提升到了49.0%,发射波长从508 nm红移到511 nm。这主要归因于OFHDODA与钙钛矿之间的物理化学相互作用有效抑制了非辐射复合,一方面多氟结构与PEA+之间的氢键相互作用调控了结晶动力学,抑制了低维相的产生;另一方面酯基具有较强的路易斯碱性,钝化了表界面未饱和Pb2+缺陷。相应地,准二维钙钛矿LED的外量子效率(External Quantum Efficiency,EQE)从8.55%提高到了13.76%。这项工作为设计新型多功能小分子添加剂,抑制准二维钙钛矿中的非辐射复合损失提供了思路。
任书霞, 杨铮, 安帅领, 孟婕, 刘晓敏, 赵晋津
2023, 39(12): 230103  doi: 10.3866/PKU.WHXB202301033
[摘要]  (180) [HTML全文] (180) [PDF 3018KB] (180)
光电阻变存储器(RRAM)因其微型化、集成化和多功能等优点成为下一代非易失性存储器中最有前途的竞争者。采用低温旋涂法合成具有绿色荧光的无机CsPbBr3量子点(QDs)为阻变功能层,制备了高效光电调控的Ag/CsPbBr3 QDs/ITO RRAM器件。该器件具有良好的抗疲劳性能和保持特性。在光照触发下,Ag/CsPbBr3 QDs/ITO器件的开关比(ON/OFF比)约为3.2 × 103,较暗态增大了约24倍;写入电压(V SET)为2.88 V,较暗态降低了约13.3%。电场作用下Br和Ag+双离子迁移形成混合导电细丝的通断是Ag/CsPbBr3 QDs/ITO器件阻变的主要机制。经光照激发作用,CsPbBr3 QDs薄膜内缺陷密度的减少促进光电流的增大,促进了Ag/CsPbBr3 QDs/ITO器件低阻态(LRS)阻值和V SET减小、进而提高器件ON/OFF比。高效光电调控全无机钙钛矿RRAM技术推动了高密度信息存储器的快速发展。
常建桥, 许慧敏, 谢文菁, 张洋, 祁玲, 范楼珍, 李勇
2023, 39(12): 230103  doi: 10.3866/PKU.WHXB202301034
[摘要]  (104) [HTML全文] (104) [PDF 4412KB] (104)
逆转录-实时荧光定量聚合酶链式反应(RT-qPCR)已经广泛应用于核酸检测。然而,如何实现准确、快速即时检测仍然是亟待解决的关键问题。本研究设计了一种使用胍基修饰的荧光碳点(GCDs),用于高灵敏度以及高特异性的快速核酸检测。当GCDs与分子信标(Beacon)通过氢键作用结合后,GCDs的荧光被Beacon的荧光基团淬灭。当遇到目标核酸(Target DNA)之后,Beacon与Target DNA进行碱基互补配对,GCDs与Beacon脱离,GCDs自身荧光恢复。基于这种灵敏的荧光“off-on”,可实现在5 min内快速准确核酸检测,并可检测到体系内0.005 fmol∙L−1 (约300 copys∙mL−1)的核酸序列,相比于RT-qPCR所需要的2–4 h,该方法不需要进行核酸扩增,缩短了检测时间,有望为目前的核酸检测提供一个便捷有效的方法。
Recent Advances in Self-Supported Transition-Metal-Based Electrocatalysts for Seawater Oxidation
Qian Wu, Qingping Gao, Bin Shan, Wenzheng Wang, Yuping Qi, Xishi Tai, Xia Wang, Dongdong Zheng, Hong Yan, Binwu Ying, Yongsong Luo, Shengjun Sun, Qian Liu, Mohamed S. Hamdy, Xuping Sun
2023, 39(12): 230301  doi: 10.3866/PKU.WHXB202303012
[摘要]  (104) [HTML全文] (104) [PDF 9439KB] (104)
Seawater electrolysis is a promising and sustainable technology for green hydrogen production. However, some disadvantages include sluggish kinetics, competitive chlorine evolution reaction at the anode, chloride ion corrosion, and surface poisoning, which has led to a decline in activity and durability and low oxygen evolution reaction (OER) selectivity of the anodic electrodes. Benefiting from the lower interface resistance, larger active surface, and superior stability, the self-supported nanoarrays have emerged as advanced catalysts compared to conventional powder catalysts. Self-supported catalysts have more advantages than powder catalysts, particularly in practical large-scale hydrogen production applications requiring high current density. During electrolysis, due to the influx of bubbles generated on the electrode surface, the powdered nanomaterial is peeled off easily, resulting in reduced catalytic activity and even frequent replacement of the catalyst. In contrast, self-supported nanoarray possessing strong adhesion between the active species and the substrates ensures good electronic conductivity and high mechanical stability, which is conducive to long-term use and recycling. This minireview summarizes the recent progress of self-supported transition-metal-based catalysts for seawater oxidation, including (oxy)hydroxides, nitrides, phosphides, and chalcogenides, emphasizing the strategies in response to the corrosion and competitive reactions to ensure high activity and selectivity in OER processes. In general, constructing three-dimensional porous nanostructures with high porosity and roughness can enlarge the surface areas to expose more active sites for oxygen evolution, which is an efficient strategy for improving mass transfer and catalytic efficiency. Furthermore, the Cl barrier layer on the surface of catalyst, particularly that with both catalytic activity and protection, can effectively inhibit the competitive oxidation and corrosion of Cl, thereby delivering enhanced catalytic activity, selectivity, and stability of the catalysts. Moreover, developing super hydrophilic and hydrophobic surfaces is a promising strategy to increase the permeability of electrolytes and avoid the accumulation of large amounts of bubbles on the surface of the self-supported electrodes, thus promoting the effective utilization of active sites. Finally, perspectives and suggestions for future research in OER catalysts for seawater electrolysis are provided. In particular, the medium for seawater electrolysis should be transferred from simulated saline water to natural seawater. Considering the challenges faced in natural seawater splitting, in addition to designing and synthesizing self-supported catalysts with high activities, selectivity, and stability, developing simple and low-cost natural seawater pretreatment technologies to minimize corrosion and poisoning issues is also an important topic for the future development of seawater electrolysis. More importantly, a standardized, feasible evaluation system for self-supported electrocatalysts should be established. In addition, factors such as the intrinsic activity, density of accessible active sites, size, mass loading, substrate effects, and test conditions of the catalyst should be fully considered.



















LIEBER Charles M.

Harvard University








Harvard University, 北京大学


 Duke University



























University of Delaware




Stanford University






















Carnegie Mellon University




McGill University












University of North Carolina




































National University of Singapore




















发布时间: 2018-05-02





发布日期:2009-06-24 浏览: