SiO x Interfacial Engineering of UV/Ozone Oxidation for an Efficient Water-Reduction Metal–Insulator–Semiconductor Silicon Photocathode

• Published in: ACS catalysis 2024-11, Vol.14 (23), p.17945-17957
• Main Authors: Jiang, Chenxiao, Zhou, Siqin, Han, Jinlu, Xie, Guancai, Gong, Jian Ru, Zhang, Juan
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.4c05792

A metal–insulator–semiconductor (MIS) structure is an attractive interfacial structure for efficient photoelectrochemical (PEC) water-splitting reactions. However, developing a cost-effective and highly active photoelectrode for the PEC water-splitting reaction is still a major challenge. In this study, we use an easy-to-operate and economical UV/ozone (UV/O3) oxidation process to prepare ultrathin SiO x oxide as an insulating layer, which is integrated with the bilayer non-precious-metal collector Al/Ni serving as the catalyst and the p-Si semiconductor to obtain a cost-effective and efficient MIS structure photocathode. The outcomes demonstrate that the ultrathin SiO x insulation layer significantly improves the PEC hydrogen evolution reaction (HER), through comparing the photovoltage and photocurrent density of the MIS system. The inner metal Al in the bilayer collector Al/Ni regulates the degree of band bending at the semiconductor–metal interface. Additionally, the presence of the ultrathin Al2O3 insulation layer effectively reduces Fermi-level pinning, which promotes the efficient transfer of photoelectrons to electrolytes. These were confirmed through photoelectric performance testing of the MIS system. The generation of a photocurrent of 15 mA cm–2 at a potential level of 0 V (vs reversible hydrogen electrode) has been obtained by optimizing the thickness of the SiO x and bilayer non-precious-metal collector. This study presents an economical and efficient strategy for enhancing PEC-HER performance in silicon-based photocathodes using an MIS structure.