Cheng Jinshui, Wu Linxiao, Luo Jingshan
Institute of Photoelectronic Thin Film Devices and Technology, State Key Laboratory of Photovoltaic Materials and Cells, Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin, Ministry of Education Engineering Research Center of Thin Film Photoelectronic Technology, Renewable Energy Conversion and Storage Center, Nankai University, 300350, Tianjin, China.
Frontiers Science Center for New Organic Matter, Nankai University, 300071, Tianjin, China.
Nat Commun. 2023 Nov 9;14(1):7228. doi: 10.1038/s41467-023-42799-x.
Cuprous oxide (CuO) is a promising oxide material for photoelectrochemical water splitting (PEC), and increasing its photovoltage is the key to creating efficient overall PEC water-splitting devices. Previous reports are mostly focused on optimizing the energy band alignment between CuO and the n-type buffer layer to improve the photovoltage of CuO photocathodes. However, the band alignment between the n-type buffer layer and the protective layer is often ignored. In this work, CuO photocathodes with a single buffer layer (GaO) and dual buffer layers (GaO/ZnGeO) are fabricated, and their PEC performances are compared. Results show that after inserting the second buffer layer (ZnGeO), the onset potential of the CuO photocathode increases by 0.16 V. Operando electrochemical impedance spectroscopy measurements and analysis of the energy-level diagrams of each layer show that an energy level gradient between GaO and TiO is created when ZnGeO is introduced, which eliminates the potential barrier at the interface of GaO/TiO and improves the photovoltage of the CuO photocathode. Our work provides an effective approach to improve the photovoltage of photoelectrodes for solar water splitting by introducing dual buffer layers.
氧化亚铜（CuO）是一种用于光电化学水分解（PEC）的很有前景的氧化物材料，提高其光电压是制造高效的整体PEC水分解装置的关键。先前的报道大多集中在优化CuO与n型缓冲层之间的能带排列，以提高CuO光阴极的光电压。然而，n型缓冲层与保护层之间的能带排列常常被忽视。在这项工作中，制备了具有单一缓冲层（GaO）和双缓冲层（GaO/ZnGeO）的CuO光阴极，并比较了它们的PEC性能。结果表明，插入第二缓冲层（ZnGeO）后，CuO光阴极的起始电位增加了0.16 V。原位电化学阻抗谱测量和各层能级图分析表明，引入ZnGeO时，在GaO和TiO之间产生了能级梯度，消除了GaO/TiO界面处的势垒，提高了CuO光阴极的光电压。我们的工作提供了一种通过引入双缓冲层来提高用于太阳能水分解的光电极光电压的有效方法。
