Feng Chao, Liu Zhi, Ju Huanxin, Mavrič Andraž, Valant Matjaz, Fu Jie, Zhang Beibei, Li Yanbo
Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, China.
Key Laboratory of Quantum Physics and Photonic Quantum Information, Ministry of Education, University of Electronic Science and Technology of China, Chengdu, China.
Nat Commun. 2024 Jul 31;15(1):6436. doi: 10.1038/s41467-024-50893-x.
The buried interface tens of nanometers beneath the solid-liquid junction is crucial for photocarrier extraction, influencing the overall efficiency of photoelectrochemical devices. Precise characterization of the interfacial properties is essential for device optimization but remains challenging. Here, we directly probe the in situ transformation of a CuO interlayer at the NiO/n-Si interface by hard X-ray photoelectron spectroscopy. It is found that Cu(I) in the CuO interlayer gradually transforms to Cu(II) with air exposure, forming an energetically more favorable interface and improving photoanode's efficiency. Based on this finding, a reactive e-beam evaporation process is developed for the direct deposition of a CuO interlayer, achieving a half-cell solar-to-hydrogen efficiency of 4.56% for the optimized NiO/CuO/n-Si heterojunction photoanode. Our results highlight the importance of precision characterization of interfacial properties with advanced hard X-ray photoelectron spectroscopy in guiding the design of efficient solar water-splitting devices.
固液结下方几十纳米处的掩埋界面对于光载流子提取至关重要，影响着光电化学器件的整体效率。界面性质的精确表征对于器件优化至关重要，但仍然具有挑战性。在此，我们通过硬X射线光电子能谱直接探测NiO/n-Si界面处CuO中间层的原位转变。研究发现，CuO中间层中的Cu(I)随着空气暴露逐渐转变为Cu(II)，形成了能量上更有利的界面，提高了光阳极的效率。基于这一发现，开发了一种反应性电子束蒸发工艺用于直接沉积CuO中间层，优化后的NiO/CuO/n-Si异质结光阳极实现了4.56%的半电池太阳能制氢效率。我们的结果突出了利用先进的硬X射线光电子能谱精确表征界面性质在指导高效太阳能水分解器件设计中的重要性。
