State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, Hunan, China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China.
Adv Mater. 2018 Aug;30(31):e1801773. doi: 10.1002/adma.201801773. Epub 2018 Jun 19.
Silicon (Si) requires a protection layer to maintain stable and long-time photoanodic reaction. However, poor charge separation and transfer are key constraint factors in protection layer/Si photoanodes that reduce their water-splitting efficiency. Here, a simultaneous enhancement of charge separation and transfer in Nb-doped NiO /Ni/black-Si photoanodes induced by plasma treatment is reported. The optimized photoanodes yield the highest charge-separation efficiency (η ) of ≈81% at 1.23 V versus reversible hydrogen electrode, corresponding to the photocurrent density of ≈29.1 mA cm . On the basis of detailed characterizations, the concentration and species of oxygen defects in the NiO -based layer are adjusted by synergistic effect of Nb doping and plasma treatment, which are the dominating factors for forming suitable band structure and providing a favorable hole-migration channel. This work elucidates the important role of oxygen defects on charge separation and transfer in the protection layer/Si-based photoelectrochemical systems and is encouraging for application of this synergistic strategy to other candidate photoanodes.
硅（Si）需要保护层来维持稳定和长时间的光电阳极反应。然而，在保护层层/Si 光电阳极中，电荷的分离和转移较差是降低其水分解效率的关键限制因素。在这里，报道了等离子体处理诱导的掺铌氧化镍/镍/黑硅光电阳极中电荷分离和转移的同时增强。优化后的光电阳极在 1.23 V 相对于可逆氢电极时产生的电荷分离效率（η）约为 81%，对应的光电流密度约为 29.1 mA cm-2。基于详细的特性分析，协同效应的 Nb 掺杂和等离子体处理调整了基于 NiO 的层中的氧缺陷浓度和种类，这是形成合适能带结构和提供有利空穴迁移通道的主要因素。这项工作阐明了氧缺陷在保护层/Si 基光电化学系统中对电荷分离和转移的重要作用，并为将这种协同策略应用于其他候选光电阳极提供了鼓舞。
