多元复合分级阵列光电极的制备及其光电化学性能研究

Photoelectrochemical water splitting technology is one of the promising technologies for using solar energy to relieve the crisis. Design and develop a photoanode with stable performance, high light utilization rate, and excellent carrier separation and transmission performance is an important research direction in the field of photoelectrochemical water splitting. In this proposal, ZnO nanowires/vertical carbon nanotube arrays (ZnO NWs/VACNTs) nanostructures were used as microscopic carriers to support carbon nitride/graphene (CNG) with excellent photochemical activity, good sheet structure, and dispersibility to form CNG/ZnO NWs/VACNTs photoanode. .Based on the microscopic spectra, phase, morphology and electronic structure characterization and analysis, the structure-activity relationship experiment and theoretical study of muti-component photoanode were carried out. This project explored the relationship between the composition, morphology, structure and surface chemical properties of photoelectrode and the light absorption, band structure, effective separation and migration of photoexcited charge, and found the key factors which improve or limit the water splitting performance of photoelectrode. The photo-induced charge separation, transport mechanism and charge transfer characteristics at the electrode/electrolyte interface were studied to provide theoretical basis for controlling the carrier separation efficiency and the carrier/electrode separation efficiency at the electrode/electrolyte interface to achieve incident photon-to-electron conversion efficiency and PEC water splitting properties improvements.

光电化学分解水技术是利用太阳能缓解能源危机极具前景的技术之一。设计、开发性能稳定、光利用率高以及载流子分离与传输性能优异的光阳极是其重要研究方向。本项目以高比表面积、多重电子传递路径的氧化锌纳米线/垂直碳纳米管阵列（ZnO NWs/VACNTs）作为微观载体，与样品缺陷少、片层结构完整且具有良好光化学活性的氮化碳/石墨烯（CNG）共轭碳纳米结构复合，构筑多元异质光阳极CNG/ZnO NWs/VACNTs。以其微观形貌、光谱、物相、电子结构、光电化学特性表征及分析为手段，开展异质光阳极构效关系实验及理论研究。通过研究光电极组成、形貌、结构及表面化学特性与光吸收、能带结构、光生电荷有效分离迁移的关系，阐明提高和限制光阳极性能的关键因素。分析光致电荷分离传输机理，电极/电解液界面电荷传递特性，调控异质光阳极内部及电极/电解液界面载流子分离效率，实现光电化学转换效率及分解水性能的提高。

利用太阳能分解水制氢已经成为解决我国能源短缺和环境污染问题的有效途径之一。 开发高效稳定的太阳能转换材料体系是其中的关键。本项目以调控异质结内部及电极/电解液界面载流子分离效率为目标，构筑多元分级结构异质复合体系。通过微观形貌、光谱、物相、电子结构、光/电化学特性表征及分析手段，以多元复合光电极的微观设计、宏观光解水性能，与光致电荷分离、迁移机理结合，确定光电极特性的影响因素为出发点，构建了性能稳定、光利用率高以及载流子分离与传输性能优异的复合体系并开展了实验与理论研究。为改善体相材料较高的激子结合能和较低结晶度对光生电子-空穴对快速迁移和分离的不利影响，本项目研究中对表面官能团及表面缺陷结构进行调控和优化，研究各组分的相互作用及其对电学、光学性能的影响。通过能级匹配形成有利于电荷有效传输的异质结，获得结构良好、分散性好、缺陷少的光活性物质。通过表面化学性能优化，增强对光的吸收利用及对光生载流子的收集效率，为载流子提供必需的分离界面，并且分离后的光生载流子沿着多重传输通道迁移，阻碍迁移过程中的复合。同时，加强表面活性位点和电解液的渗透，提高异质结构光电化学活性及产氢效率。分析光致电荷分离传输机理，考察复合界面电荷传递特性；通过阻抗谱等电化学方法考察电荷传输特性。对光致电荷分离、传输机理进行分析，对光电极/电解液界面电荷传递性能考察，调控载流子的分离效率。最后，结合理论计算模拟，分析整个过程中，表面吸附，分子解离及产氢步骤中各组分的作用，确定限制及提高异质电极材料光解水影响因素提供理论指导和依据。本项目研究成果将为构筑高效光电化学体系提供基础数据和理论参考。