Spontaneous decoration of silicon surfaces with MoO x nanoparticles for the sunlight-assisted hydrogen evolution reaction.

The immersion of oxide-free Si surfaces in MoS4 2- aqueous solutions induces their spontaneous decoration with isolated MoOx nanoparticles (NPs). The process is versatile and was used on planar Si (100) as well as on antireflective Si (111) micro-pyramid (SimPy) arrays. The NP decoration does not affect the optical properties of the surface in the visible range and improves the performance of the hydrogen evolution reaction (HER) under simulated sunlight. The simplicity and the scalability of the technique make it highly promising for the fabrication of catalytically active photoelectrodes. More specifically, the MoOx -decorated SimPy produced H2 at a rate of 11 μmol cm-2 min-1 with a faradaic efficiency higher than 90% at -0.35 V vs. RHE. Furthermore, this process can be of great interest for other applications in high-performance electronic devices.