Li Huimin, Wang Tuo, Liu Shanshan, Luo Zhibin, Li Lulu, Wang Huaiyuan, Zhao Zhi-Jian, Gong Jinlong
Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China.
Angew Chem Int Ed Engl. 2021 Feb 19;60(8):4034-4037. doi: 10.1002/anie.202014538. Epub 2020 Dec 21.
Silicon is a promising photocathode material in photoelectrochemical water splitting for hydrogen production, but it is primarily limited by photocorrosion in aqueous electrolytes. As an extensively used protective material, crystalline TiO could protect Si photoelectrode against corrosion. However, a large number of grain boundaries (GBs) in polycrystalline TiO would induce excessive recombination centers, impeding the carrier transport. This paper describes the introduction of oxygen vacancies (O ) with controllable spatial distribution for GBs to promote carrier transport. Two kinds of O distribution, O along GBs and O inside grains, are compared, where the latter one is demonstrated to facilitate carrier transport owing to the formation of tunneling paths across GBs. Consequently, a simple p-Si/TiO /Pt heterojunction photocathode with controllable O distribution in TiO shows a +400 mV onset potential shift and yields an applied bias photon-to-current efficiency of 5.9 %, which is the best efficiency reported among silicon photocathodes except for silicon homojunction.
硅是光电化学水分解制氢中一种很有前景的光阴极材料，但它主要受限于在水性电解质中的光腐蚀。作为一种广泛使用的保护材料，晶体TiO可以保护硅光电极免受腐蚀。然而，多晶TiO中的大量晶界会诱导过多的复合中心，阻碍载流子传输。本文描述了为晶界引入具有可控空间分布的氧空位（O）以促进载流子传输。比较了两种O分布，即沿晶界的O和晶粒内部的O，其中后者由于形成了跨越晶界的隧穿路径而被证明有助于载流子传输。因此，一种在TiO中具有可控O分布的简单p-Si/TiO/Pt异质结光阴极显示出400 mV的起始电位偏移，并产生了5.9%的外加偏压光子到电流效率，这是除硅同质结外硅光阴极中报道的最佳效率。
