In-situ environmental TEM studies of electro- and photo-electrochemical systems for water splitting

尽管近年来取得了重要的进展，但迄今为止已经确定的用于水分解和氢气生产的光电化学系统仍然受到转换效率、贵金属催化剂成本或水环境腐蚀稳定性的阻碍。设计改进的非贵金属电催化剂并将其集成到稳定的光电极中需要阐明决定其活性和稳定性的机制。本项目的主要目标是提高对水分解过程中析氢和析氧电催化剂的原子和电子结构的基本理解，并改进在多结半导体光电电化学器件中集成光电阴极和阳极的策略。分析和环境透射电子显微镜（ETEM）具有可控的原位电和光刺激，将用于研究从器件级到原子级不同长度尺度的结构和过程。这样就可以获得制备状态下电极的微观结构，包括催化剂粒度、形貌、表面覆盖率以及电极缓冲层和半导体的界面性质。此外，还将研究电催化剂在水分解过程中在活性状态下的原子和电子结构的变化，以及导致光电化学器件降解和腐蚀的过程。我们在spp1613中讨论了三个高度相关的系统，即硅基串联和三重结，以及具有不同催化剂（Pt, Rh, MoS2）的III-V复合光阴极。此外，还将对锰基和co -氧化物基析氧电催化剂的活性状态进行原位研究。基于对水蒸汽中由电和光刺激引起的过程的更好理解，将与SPP内的伙伴小组密切合作，制定改进电催化剂及其在光电化学装置中的集成的开发指南。

Despite important developments in recent years, photo-electrochemical systems for water splitting and production of H2 that have been identified so far are still hampered either by conversion efficiency, the costs of noble metal catalysts or by corrosion stability in aqueous environments. Design of improved non-noble electro-catalysts and integration into stable photo-electrodes requires elucidating the mechanisms determining their activity and stability.The main goal of this proposed project is an improved fundamental understanding of the atomic and electronic structure of electro-catalysts for hydrogen- and oxygen-evolution during water splitting and improved strategies for integration into photocathodes and anodes in multi-junction semiconductor photo-electrochemical devices. Analytical and environmental Transmission Electron Microscopy (ETEM) with controlled in-situ electric and optical stimulation will be applied for studying structure and processes on different length scales from device level down to atomic scales. This gives access to the microstructure of the electrodes in the as prepared state, including catalyst particle size, morphology, surface coverage and interface properties to electrode buffer layers and semiconductors. Furthermore, the change of the atomic and electronic structure of the electro-catalysts in their active state during water splitting will be studied as well as processes leading to degradation and corrosion of the photo-electrochemical devices. We address three systems of high relevance within the SPP 1613, i.e. Si-based tandem and triple junctions as well as III-V compound photo-cathodes with different catalysts (Pt, Rh, MoS2) for hydrogen evolution. In addition, active states of Mn- and Co-oxide based electro-catalysts for oxygen evolution will be studied in-situ. Based on the improved understanding of processes which are induced by electrical and optical stimulation in H2O vapor, guidelines for development of improved electro-catalyst and their integration in photo-electro-chemical devices will be developed in close collaboration with the partner groups within the SPP.