A hierarchical SiPN/CN/MoSx photocathode with low internal resistance and strong light-absorption for solar hydrogen production

Abstract The Si/MoSx photocathode is usually fabricated by electrochemical deposition, which high interfacial resistance is usually solved by building a buried junction or inserting a metal layer between Si and MoSx. Both methods, however, involve toxic gas sources or harsh conditions of high pressure. Here, a green and mild route has been designed to insert the N-doped carbon (CN) layer between Si and MoSx by in situ polymerization and post-annealing, which improves the transfer of interfacial carriers and avoids unnecessary absorption of incident light by itself. Meanwhile, combining two-step wet etching and photo-assisted electro-deposition, the SiPN/CN/MoSx photocathode with antireflective structure was obtained. The SiPN/CN/MoSx hybrid photocathode shows excellent performance (0.23 V onset potential and 10 mA·cm-2 photocurrent at 0 V vs RHE in 0.5 M H2SO4 under the condition of simulated sunlight). The design of SiPN/CN/MoSx photocathode will provide a new idea for PEC water splitting.