Si光阳极稳定性提高策略研究进展

Research Progress on Improvement Strategies of Silicon Photoanode Stability

利用光电化学水分解技术实现绿氢制取是解决人类面临的能源危机和环境污染的极有效与可行的途径之一,受到广泛的关注与研究。半导体Si作为一种优异的光电极材料,具有理想的1.12 eV窄带隙、宽太阳光谱吸收范围(300~1100 nm)、高的载流子传输性能(晶体硅μn=1350 cm^(2)/(V·s),μp=500 cm^(2)/(V·s),常温)以及高结晶性等优点。但是,Si的价带边远低于水分解析氧反应1.23 VRHE,以及析氧反应涉及四电子转移过程,导致Si光阳极本征析氧反应动力学缓慢;同时,Si光阳极表面会生成绝缘性SiO_(2)层或SiO_(2)(OH)^(2-)层,导致严重的光腐蚀和稳定性问题等,成为限制其实际应用的重大挑战。近年来,研究者提出了许多提高Si光阳极光氢转换效率与稳定性的策略。本文重点对Si光阳极的提高策略研究进展进行综述,包括催化层、保护层、电解液保护以及界面工程四类;其次对光电化学水分解基本原理以及Si半导体材料作光阳极的可行性与优缺点进行分析;最后基于上述研究进展,对提高Si光阳极效率与稳定性的未来发展进行了综述与展望。

Green hydrogen produced by photoelectrochemical water splitting technology is one of the most effective and feasible approaches to solve the energy crisis and environmental pollution,which has attracted extensive attention and research.The semiconductive silicon is an excellent photoelectrode material,which has several advantages such as an ideal narrow band gap of 1.12 eV,the wide solar spectrum absorption(300—1100 nm),and the high carrier mobility(Crystal Si,μn=1350 cm^(2)/(V·s),μp=500 cm^(2)/(V·s),RT)and high crystallinity.However,the valence band edge is far lower than the potential of water oxidation(1.23 VRHE).The water oxidation reaction is a four-electron transfer process.Thus,the intrinsic oxygen evolution kinetics of silicon photoanodes is sluggish.Meanwhile,the insulating SiO_(2) or/and SiO_(2)(OH)^(2-)generated on the surface of silicon photoanodes would induce the serious photocorrosion and the issue of stability.The above limits greatly hinder the practical applications of silicon photoanodes.Recently,researchers have developed some strategies to improve the solar-to-hydrogen efficiency and stabi-lity of silicon photoanodes.This review focuses on the research progress of protection strategies of silicon photoanodes,including four improvement strategies:catalytic layer,protective layer,electrolyte protection and interface engineering.Secondly,the basic principle of photoelectrochemical water splitting and the feasibility,advantages and disadvantages of silicon semiconductor material as photoanode are analyzed.Finally,we discuss the perspectives on the potential investigation directions for improving the efficiency and stability of silicon photoanodes.