梯度型MoS2(1-x)Se2x/TiO2复合纳米结构阵列太阳能转化制氢及其失效控制研究

In recent years, the artificial design of nanostructures for hydrogen production by solar energy is receiving great attention. Narrow band-gap alloy semiconductors with tunable chemical composition recently become a research hotspot in nanoscience and nanotechology, due to their great potential applications in future optoelectronic and energy devices. This program is aim to explore the alloy hybrid nanostructures integrated with gradient-type MoSe2(1-x)S2x/TiO2 light absorption matrix and Co-Pi water oxidation catalyst (WOC) for solar-water splitting. With proper composition grading in MoSe2(1-x)S2x/TiO2 hybrids, band gap engineering as well as continuous light responses for hydrogen generation from water-splitting among a wide range of solar spectrum should be realized. Thereafter, by studying the aging progress, disabled time and reliability of the photoelectrodes under condition of service, the oxygen evolution catalyst Co-Pi with self-hearing feature will be introduced to overcome the problem of self-degradation in MoSe2(1-x)S2x/TiO2 narrow bandgap semiconductors. Our program will provide new paradigms for designing 1D nanoframework/alloy light absorber/WOC photoanode to simultaneously enhance light absorption, charge separation/transport and surface water oxidation reaction for efficient and stable solar fuel application.

近年来，人工设计纳米结构用于太阳能转化制氢正受到极大的关注。本项目拟采用集梯度型吸光基质与析氧电催化于一体的办法来综合提升复合光电极的光电转换效率和抗光致失效本领。研究具有核/壳结构的MoSe2(1-x)S2x/TiO2新宽谱纳米异质结制备及其多功能集成复合光解水微观结构调控和性能优化。研究梯度型MoSe2(1-x)S2x吸光壳层的化学组份对光吸收带边、吸收强度，光生电子和空穴分离、复合，界面电荷的传递和俘获等的影响。通过探索使役条件下复合光电极的失效规律、失效时间以及可再生条件总结和分析失效原因并进行失效控制研究。研究获取具有自主知识产权的失效控制新方法以及纯无机析氧催化剂Co-Pi诊断下MoS2(1-x)Se2x/TiO2复合宽谱吸光异质结光解水的稳定机制，为进一步探索宽光谱、持久型太阳能转化制氢应用提供科学依据。

光子吸收和表面催化转化是光解水制氢领域的两个关键问题，然而广泛的研究结果表明单一半导体光电极在实现高效光解水制氢方面面临着极大的效率瓶颈。本项目主要探索复合光电异质结中能带梯度、表面析氧催化与太阳能转化制氢之间的构效关系，并开展使役条件下复合光电极的失效和可再生条件研究。4年来项目进展顺利，课题组重点围绕TiO2复合光电极中的光子吸收、表界面调控以及Co-Pi等助催化剂修饰后光电极表面的析氧催化机理开展了系列研究。按照计划，完成了以TiO2为电子传输层与MoSx、MoS2xSe2(1-x)、BiVO4、α-Fe2O3等窄带隙吸光材料复合后的光电化学制氢能性研究。结果表明，以上窄带材料在拓宽复合光电极光谱吸收范围，提升光电催化制氢效率方面起到积极作用。与此同时，通过在使役条件下催化剂的可靠性研究，探明了Co-Pi做为析氧助催化剂在水的光电化学氧化还原反应过程中具有的自修复效应，并结合实验和理论阐明了Co-Pi在降低反应能垒和提升窄带隙材料光电化学制氢稳定性等方面的内在机理。项目所取得的研究成果为长效化太阳能转化制氢应用进程中的相关物理和化学问题提供了较为重要的科学依据。