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1.
van der Waals(vd Ws) heterostructures based on two-dimensional(2D) materials have become a promising candidate for photoelectrochemical(PEC) catalyst not only because of the freedom in materials design that enable the band-offset construction and facilitate the charge separation. They also provide a platform for the study of various of interface effect in PEC. Here, we report a new kind of mixed-dimensional vd Ws heterostructure photoelectrode and investigate the strain enhanced PEC performance ...  相似文献   

2.
Cu2O is an ideal p-type material for photo-electrochemical (PEC) hydrogen evolution, although serious electron–hole recombination and photocorrosion restrict its further improvement for PEC activity. In this work, CeO2 nanoparticles (NPs) self-assemble on the surface of Cu2O octahedra, thus successfully forming a Cu2O/CeO2 structure in which p–n heterojunctions and micro-mesocrystals (m-MCs) work together. The optimum Cu2O/CeO2 composite, without the use of any cocatalyst, exhibits a fivefold higher photocurrent density (4.63 mA cm−2 at 0 V vs. the reversible hydrogen electrode) than that of Cu2O octahedra, which is better than most Cu2O-based photocathodes without cocatalyst and even comparable with advanced Cu2O-based photocathodes. The hydrogen production of the optimal Cu2O/CeO2 (Faradaic efficiency of ∼100 %) is 17.5 times higher than that of pure Cu2O octahedra, and the photocurrent shows almost no decay under the 12 h stability test. The delicately designed Cu2O/CeO2 structure in this work provides reference and inspiration for the design of cathodes materials.  相似文献   

3.
In photocatalysis, the Schottky barrier in metal–semiconductor hybrids is known to promote charge separation, but a core–shell structure always leads to a charge build-up and eventually shuts off the photocurrent. Here, we show that Au–Cu2O hybrid nanostructures can be continuously tuned, particularly when the Cu2O domains are single-crystalline. This is in contrast to the conventional systems, where the hybrid configuration is mainly determined by the choice of materials. The distal separation of the Au–Cu2O domains in Janus nanostructures leads to enhanced charge separation and a large improvement of the photocurrent. The activity of the Au–Cu2O Janus structures is 5 times higher than that of the core–shell structure, and 10 times higher than that of the neat Cu2O nanocubes. The continuous structural tuning allows to study the structure–property relationship and an optimization of the photocatalytic performance.  相似文献   

4.
The emergence of cuprous oxide (Cu2O) as a visible light active semiconductor for photocatalytic and photoelectrochemical applications has elevated significantly over the past decade. With photocorrosion identified as a severe issue for Cu2O, its photoactivity has been greatly restricted. Given that Cu2O redox potentials are located in between its band gap, the possible occurrence of self-photoreduction or self-oxidation upon illumination is inevitable. Various efforts have been directed to implement effective strategies in enhancing the photostability of Cu2O. In particular, most of the studies focused on improving the charge transfer from Cu2O to reactants or co-catalyst to avoid accumulation of charge within the particles. This review presents recent research progresses for the development of strategies to suppress Cu2O photocorrosion in regards to its intrinsic properties and charge kinetics. It is shown that effective transport of electrons or holes out of Cu2O photocatalyst by engineering its crystal structure, tuning its reaction environment or depositing secondary elements could effectively inhibit Cu2O from experiencing self-photodecomposition. Understanding of the charge dynamics with respect to its photocorrosion is pivotal to optimize the design of Cu2O photocatalyst for enhanced performance in the future.  相似文献   

5.
Hematite(α-Fe_2O_3) is a promising photoanode for photoelectrochemical(PEC) water splitting.However,the severe charge recombination and sluggish water oxidation kinetics extremely limit its use in photohydrogen conversion.Herein,a co-activation strategy is proposed,namely through phosphorus(P)doping and the loading of CoAl-layered double hydroxides(CoAl-LDHs) cocatalysts.Unexpectedly,the integrated system,CoAl-LDHs/P-Fe_2O_3 photoanode,exhibits an outstanding photocurrent density of 1.56 mA/cm~2 at 1.23 V(vs.reversible hydrogen electrode,RHE),under AM 1.5 G,which is 2.6 times of pureα-Fe_2O_3.Systematic studies reveal that the remarkable PEC performance is attributed to accelerated surface OER kinetics and enhanced carrier separation efficiency.This work provides a feasible strategy to enhance the PEC performance of hematite photoanodes.  相似文献   

6.
《中国化学快报》2022,33(8):3709-3712
Semiconductor-employed photocatalytic CO2 reduction has been regarded as a promising approach for environmental-friendly conversion of CO2 into solar fuels. Herein, TiO2/Cu2O composite nanorods have been successfully fabricated by a facile chemical reduction method and applied for photocatalytic CO2 reduction. The composition and structure characterization indicates that the Cu2O nanoparticles are coupled with TiO2 nanorods with an intimate contact. Under light illumination, all the TiO2/Cu2O composite nanorods enhance the photocatalytic CO2 reduction. In particular, the TiO2/Cu2O-15% sample exhibits the highest CH4 yield (1.35 µmol g-1 h-1) within 4 h irradiation, and it is 3.07 and 15 times higher than that of pristine TiO2 nanorods and Cu2O nanoparticles, respectively. The enhanced photoreduction capability of the TiO2/Cu2O-15% is attributed to the intimate construction of Cu2O nanoparticles on TiO2 nanorods with formed p-n junction to accelerate the separation of photogenerated electron-hole pairs. This work provides a reference for rational design of a p-n heterojunction photocatalyst for CO2 photoreduction.  相似文献   

7.
使用L-半胱氨酸作为连接剂, 利用硼氢化钠原位还原预先吸附在介孔氧化亚铜表面的氯金酸根离子,得到了Au/Cu2O异质结构. 应用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱和N2物理吸附等手段对催化剂进行表征, 并以λ>400 nm的可见光作为光源, 评价了该催化剂光催化降解亚甲基蓝(MB)的活性. 实验结果表明, 直径为4 nm的金颗粒完好地负载在介孔氧化亚铜的表面, 并且介孔氧化亚铜的细微结构与孔径均未发生变化. 研究表明, 以乙醇作为反应溶剂有效抑制了AuCl4-与Cu2O之间的氧化还原反应, 从而有利于氧化亚铜介孔结构的保持及金颗粒的原位还原. 光催化降解亚甲基蓝的结果表明, Au/Cu2O异质结构的光催化活性比纯氧化亚铜光催化活性有明显提高. 推测其光催化性能提高的主要原因如下: 一方面, 金颗粒良好的导电性有利于氧化亚铜表面电子的快速转移, 实现电子-空穴分离; 另一方面, 金颗粒可能存在的表面等离子共振现象加速了光生电子的产生.  相似文献   

8.
In this work, two kinds of ZnO/Cu2S core/shell nanorods (NRs) have been successfully synthesized from ZnO NRs for photoelectrochemical (PEC) water splitting by a versatile hydrothermal chemical conversion method (H-ZnO/Cu2S core/shell NRs) and successive ionic layer adsorption and reaction method (S-ZnO/Cu2S core/shell NRs), respectively. The photoelectrode is composed of a core/shell structure where the core portion is ZnO NRs and the shell portion is Cu2S nanoparticles sequentially located on the surface. The ZnO NRs array provides a fast electron transport pathway due to its high electron mobility properties. The optical property of both two kinds of core/shell NRs was characterized, and enhanced absorption spectrum was discovered. Our PEC system produced very high photocurrent density and photoconversion efficiency under 1.5 AM irradiation for hydrogen generation. On the basis of a versatile chemical conversion process based on the ion-by-ion growth mechanism, H-ZnO/Cu2S core/shell NRs exhibit a much higher photocatalytic activity than S-ZnO/Cu2S core/shell NRs. The photocurrent density and photoconversion efficiency of H-ZnO/Cu2S core/shell NRs are up to 20.12 mA cm?2 at 0.85 V versus SCE and 12.81 % at 0.40 V versus SCE, respectively.  相似文献   

9.
This work describes the development of a novel method for glucose determination exploiting a photoelectrochemical‐assisted batch injection analysis cell designed and constructed with the aid of 3D printer technology. The PEC‐BIA cell was coupled to a LED lamp in order to control the incidence of light on the Cu2O/Ni(OH)2/FTO photoelectroactive platform. The electrochemical characteristics of Cu2O/Ni(OH)2/FTO photoelectroactive platform were evaluated by cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy. The PEC‐BIA cell presented linear response range, limit of detection based on a signal‐to‐noise ratio of three, and sensitivity of 1–1000 μmol L?1, 0.76 μmol L?1 and 0.578 μA L μmol?1, respectively. The PEC‐BIA method presented a mean value of the recovery values of 97.0 % to 102.0 % when it was applied to glucose determination in artificial blood plasma samples which indicates the promising performance of the proposed system to determine glucose.  相似文献   

10.
刘志锋  鲁雪 《催化学报》2018,39(9):1527-1533
光电化学分解水制氢可以一并解决环境问题和能源危机,因而成为研究热点.由于TiO_2 禁带宽度较大,不能有效吸收太阳光中的可见光,使光电化学分解水制氢的应用受限.g-C_3N_4的禁带宽度约为2.7 e V,能有效吸收可见光,但g-C_3N_4薄膜制备研究较少.我们通过热聚缩合法直接在FTO导电玻璃上制备出g-C_3N_4薄膜,发现其光电化学分解水制氢稳定性不高,选择易制备的TiO_2 作为保护层可以提高g-C_3N_4的耐用性.此外,为提高g-C_3N_4光生电子空穴对的分离能力,依靠Co-Pi对光生空穴的捕获作用而将其覆盖在最外层.因此本文首次制备一种新型的g-C_3N_4/TiO_2 /Co-Pi光阳极用于光电化学分解水制氢,其中g-C_3N_4用作光吸收层,TiO_2 用作保护层,Co-Pi用作空穴捕获层.并在此基础上,通过扫描电子显微镜(SEM),X射线衍射(XRD),紫外可见光谱(UV-Vis)等手段研究了g-C_3N_4/TiO_2 /Co-Pi光阳极的形貌特征和光电化学性能.SEM、EDS和XRD结果表明,g-C_3N_4/TiO_2 /Co-Pi光阳极被成功制备在了FTO导电玻璃上,厚度约为3μm.UV-Vis测试表明,g-C_3N_4的光吸收边约为470 nm,可以有效地吸收可见光,并且g-C_3N_4的框架结构使光多次反射折射增加了光的捕获能力,由此可见,g-C_3N_4能够发挥很好的光吸收层作用.通过对g-C_3N_4光阳极,g-C_3N_4/TiO_2 光阳极和g-C_3N_4/TiO_2 /Co-Pi光阳极的电流电压测试发现,g-C_3N_4/TiO_2 光阳极的光电流密度小于g-C_3N_4光阳极,而g-C_3N_4/TiO_2 /Co-Pi光阳极的光电流密在可逆氢电极1.1 V下达到了0.346 mA?cm–2,约为单独g-C_3N_4光阳极的3.6倍.这说明Co-Pi是提升g-C_3N_4光电化学性能的主要因素.电化学阻抗测试结果发现,g-C_3N_4/TiO_2 /Co-Pi光阳极的界面电荷转移电阻小于g-C_3N_4光阳极的,这表明g-C_3N_4/TiO_2 /Co-Pi光阳极界面处载流子转移较快,同时也能促进内部光生电子空穴对的分离,整体性能的提高应该主要归因于Co-Pi对光生空穴的捕获作用.恒电压时间测试展示出g-C_3N_4/TiO_2 /Co-Pi光阳极的光电流密度在2 h测试过程中没有明显下降,表明g-C_3N_4/TiO_2 /Co-Pi光阳极是相当稳定的,具有良好的耐用性,归因于TiO_2 和Co-Pi的共同保护作用,主要归因于TiO_2 层对FTO导电玻璃上的g-C_3N_4薄膜保护,从电化学沉积Co-Pi到所有测试结束.总体而言,g-C_3N_4/TiO_2 /Co-Pi光阳极加强的光电化学性能归因于以下几个因素:(1)g-C_3N_4优异的光吸收能力;(2)TiO_2 稳定的保护提升了g-C_3N_4薄膜的耐用性;(3)Co–Pi对光生空穴的捕获有效促进了光生电子空穴对的分离.  相似文献   

11.
The properties of both Cu2+ and Cu+ ions in zeolite CuY were followed with NO and CO as probe molecules. Cu2+ was found to be located in SII, SII*, and SIII sites, whereas Cu+ was found in SII and SII* sites. The fine analysis of the spectra of Cu2+-NO and Cu+-CO adducts suggests that both in SII and in SII* sites two kinds of Cu cations exist. They differ in the positive charge, which may be related to the varying numbers of AlO4 in close proximity. The experiments of NO and CO adsorption and desorption evidenced that both Cu2+ and Cu+ sites of highest positive charge bind probe molecules most strongly but activate them to a lesser extent than the Cu sites of lowest positive charge. The experiments of reduction with hydrogen evidenced that the Cu ions of higher positive charge are first reduced by hydrogen. On the other hand, Cu sites of the lowest positive charge are first oxidized by oxygen. The experiments with CuNaY zeolites of various Cu contents suggest that the first introduced Cu (at low Cu contents) created Cu+, which was the most neutralized by framework oxygens. Such Cu cations are the most stabilized by framework oxygens.  相似文献   

12.
《中国化学快报》2023,34(1):107480
Organic semiconductors are promising candidates as photoactive layers for photoelectrodes used in photoelectrochemical (PEC) cells due to their excellent light absorption and efficient charge transport properties with the help of interfacial materials. However, the use of multilayers will make the charge transfer mechanism more complicated and decrease the PEC performance of the photoelectrode caused by the increased contact resistance. In this work, a PM6:Y6 bulk heterojunction (BHJ)-based photocathode is fabricated for efficient PEC hydrogen evolution reaction (HER) in an acidic aqueous solution. With RuO2 as an interfacial modification layer, the photocathode with a simple structure (fluorine-doped tin oxide (FTO)/PM6:Y6/RuO2) generates a maximum photocurrent density up to ?15 mA/cm2 at 0 V vs. reference hydrogen electrode (RHE), outperforming all previously reported BHJ-based photocathodes in terms of PEC performance. The highest ratiometric power-saved efficiency of 3.7% is achieved at 0.4 V vs. RHE.  相似文献   

13.
The model complex [Cu44‐S)(dppa)4]2+ ( 1 , dppa=μ2‐(Ph2P)2NH) has N2O reductase activity in methanol solvent, mediating 2 H+/2 e? reduction of N2O to N2+H2O in the presence of an exogenous electron donor (CoCp2). A stoichiometric product with two deprotonated dppa ligands was characterized, indicating a key role of second‐sphere N?H residues as proton donors during N2O reduction. The activity of 1 towards N2O was suppressed in solvents that are unable to provide hydrogen bonding to the second‐sphere N?H groups. Structural and computational data indicate that second‐sphere hydrogen bonding induces structural distortion of the [Cu4S] active site, accessing a strained geometry with enhanced reactivity due to localization of electron density along a dicopper edge site. The behavior of 1 mimics aspects of the CuZ catalytic site of nitrous oxide reductase: activity in the 4CuI:1S redox state, use of a second‐sphere proton donor, and reactivity dependence on both primary and secondary sphere effects.  相似文献   

14.
Understanding the origin of formation and active sites of oxygen evolution reaction (OER) cocatalysts is highly required for solar photoelectrochemical (PEC) devices that generate hydrogen efficiently from water. Herein, we employed a simple pH-modulated method for in situ growth of FeNi oxyhydroxide ultrathin layers on BiVO4 photoanodes, resulting in one of the highest currently known PEC activities of 5.8 mA cm−2 (1.23 VRHE, AM 1.5 G) accompanied with an excellent stability. More importantly, both comparative experiments and density functional theory (DFT) studies clearly reveal that the selective formation of Bi−O−Fe interfacial bonds mainly contributes the enhanced OER activities, while the construction of V−O−Ni interfacial bonds effectively restrains the dissolution of V5+ ions and promotes the OER stability. Thereby, the synergy between iron and nickel of FeNi oxyhydroxides significantly improved the PEC water oxidation properties of BiVO4 photoanodes.  相似文献   

15.
Photoelectrochemical (PEC) water splitting is a promising method for the conversion of solar energy into chemical energy stored in the form of hydrogen. Nanostructured hematite (α-Fe2O3) is one of the most attractive materials for a highly efficient charge carrier generation and collection due to its large specific surface area and the short minority carrier diffusion length. In the present work, the PEC water splitting performance of nanostructured α-Fe2O3 is investigated which was prepared by anodization followed by annealing in a low oxygen ambient (0.03 % O2 in Ar). It was found that low oxygen annealing can activate a significant PEC response of α-Fe2O3 even at a low temperature of 400 °C and provide an excellent PEC performance compared with classic air annealing. The photocurrent of the α-Fe2O3 annealed in the low oxygen at 1.5 V vs. RHE results as 0.5 mA cm−2, being 20 times higher than that of annealing in air. The obtained results show that the α-Fe2O3 annealed in low oxygen contains beneficial defects and promotes the transport of holes; it can be attributed to the improvement of conductivity due to the introduction of suitable oxygen vacancies in the α-Fe2O3. Additionally, we demonstrate the photocurrent of α-Fe2O3 annealed in low oxygen ambient can be further enhanced by Zn-Co LDH, which is a co-catalyst of oxygen evolution reaction. This indicates low oxygen annealing generates a promising method to obtain an excellent PEC water splitting performance from α-Fe2O3 photoanodes.  相似文献   

16.
Reducibility of Cu supported on Al2O3, zeolite Y and silicoaluminophosphate SAPO-5 has been investigated in dependence on the Cu content using a method combining conventional temperature programmed reduction (TPR) by hydrogen with reoxidation in N2O followed by a second the so-called surface-TPR (s-TPR). The method enables discrimination and a quantitative estimation of the Cu oxidation states +2, +1 and 0. The quantitative results show that the initial oxidation state of Cu after calcination in air at 400 °C, independent on the nature of the support, is predominantly +2. Cu2+ supported on Al2O3 is quantitatively reduced by hydrogen to metallic Cu0. Comparing the TPR of the samples calcined in air and that of samples additionally pre-treated in argon reveals that in zeolite Y and SAPO-5 Cu2+ cations are stabilized as weakly and strongly forms. In both systems, strongly stabilized Cu2+ ions are not auto-reduced by pre-treatment in argon at 650 °C, but are reduced in hydrogen to form Cu+. The weakly stabilized Cu2+ ions, in contrast, may be auto-reduced by pre-treatment in argon at 650 °C forming Cu+ but are reduced in hydrogen to metallic Cu0.  相似文献   

17.
基于TiO2/Ti 电极在含Cu2+溶液中的循环伏安图,调节电沉积的沉积电压,我们在TiO2平整表面制备出Cu2O和/或Cu颗粒. 通过扫描电镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)表征,发现Cu2O和Cu有不同的生长机制:Cu2O颗粒在TiO2表面分散结晶,而Cu颗粒是在已生长的颗粒上成核,从而形成堆积颗粒结构. 这是由于在Cu2O/TiO2界面和Cu/TiO2界面形成不同的能带结构,使得电子的转移方式不同. 与纯TiO2光阳极比较,可以观察到Cu2O/TiO2和Cu/TiO2异质结构的光电流均有显著增强. 特别地,存在一个电压区间使得Cu2O和Cu同时生长在TiO2表面,此时对应的光电流比较稳定并且能达到最大. 紫外-可见(UV-Vis)漫反射光谱、电化学阻抗谱(EIS)和光电流-电压特性曲线均显示,Cu2O和Cu明显有助于光的可见光吸收,同时Cu/TiO2在光电转换过程中显示更宽波段的可见光利用率. 此外,开路电压的增加、有效的电荷分离和电极/电解质界面上载流子的快速迁移也增强了材料的光电化学性质.  相似文献   

18.
A photoelectrochemical (PEC) cell can split water into hydrogen and oxygen with the assistance of solar illumination. However, its application is still limited by excessive bulk carrier recombination and sluggish surface oxygen evolution reaction (OER) kinetics. Taking SnS2 as an example, a promising layered optoelectronic semiconductor, Ar plasma treatment strategy was used to introduce a SnS/SnS2 P?N heterojunction and O?S bond near the surface of a SnS2 nanosheet array, simultaneously increasing the separation efficiency of photogenerated electron–hole pairs in the bulk and lowering the OER overpotential at the surface. The onset potential of the plasma‐treated SnS2 nanosheet array shifts negatively to 0.16 V, and the photocurrent density at 1.23 V vs. RHE boosts to 2.15 mA cm?2, which is 7 times that of pristine SnS2. This work demonstrates a facile plasma treatment strategy to modulate the energy band structure and surface chemical states for improved PEC performance.  相似文献   

19.
Wen Jing Qi  Li Qiang Chen 《Talanta》2010,80(3):1400-9503
A facile solution-phase synthesis route of highly uniform Cu2O nanospheres (Cu2O NPs) with the size of 57.7 ± 4.7 nm was developed, and then the nanoparticles were applied to live cell imaging under a common dark-field microscope. Starting from copper(II) salts, the synthesis of Cu2O NPs was made in the presence of cetyltrimethylammonium bromide (CTAB) by reducing the copper(II) with sodium borohydride (NaBH4) in aqueous medium and by aging process in the air. Monitoring of morphology evolution process of Cu2O NPs with scanning electron microscopy (SEM) and measuring of the UV-visible spectra showed that the synthesis of Cu2O NPs follows the reduction-oxidation coupled process of Cu2+ into Cu0 species at first and then the resulted Cu0 species into Cu2O NPs in the air. Light scattering (LS) features have been measured with a common spectrofluorometer and a common dark-field microscope, and it was found that the as-prepared Cu2O NPs display strong blue scattering light and can be applied for cell imaging. If incubated with human bone marrow neuroblastoma, transferrin-conjugated Cu2O NPs can get into the cells and show strong pure blue light in cytoplasm. Further investigations showed that the Cu2O NPs could be applied for probes for conformation of proteins.  相似文献   

20.
Three mixed-ligand transition metal coordination polymers with the formula of {[CuI2CuII(tpt)2(L)] · 15H2O}n ( 1 ) and {[M2(H2O)5(tpt)(L)] · 6H2O}n [M = Ni for 2 and Co for 3 ; tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine and L = 3,3'-disulfonyl-4,4'-biphenyldicarboxylate] were hydrothermally synthesized by varying the cheap paramagnetic metal ions and used as photocatalysts for hydrogen evolution from water splitting and rhodamine B (RhB) degradation. Single-crystal structural determinations reveal that 1 is a robust pillared-layer framework with unusual 72-membered {Cu6(tpt)6} macrocycle-based layers supported by tetratopic L4– connectors. Both 2 and 3 are isostructural (4 4) sheets with octahedral NiII and CoII ions extended by ditopic L4– and tpt linkages, in which the third pyridyl group of tpt is capped by pentahydrated metal ions. Due to the narrowed bandgap and good charge transport of the mixed-valence CuI/II centers, 1 exhibits improved dual-functional catalytic activities than 2 and 3 with the visible-light-driven hydrogen evolution rate and RhB degradation efficiency up to 588 μmol · g–1 · h–1 and 72 % after 180-minute irradiation. These interesting results indicate the importance of the metal ions and the dimensionality of the coordination polymers on the activity of the non-Pt coordination polymer photocatalytic systems.  相似文献   

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