Improving the Stability of Silicon Nanowires During Photoelectrochemical Hydrogen Generation with Zinc 1T‐Phase Molybdenum Disulfide

Abstract Semiconductor photoelectrodes directly convert sunlight into stored chemical energy. In photoelectrochemical (PEC) devices, this photoconversion process relies on the junction between the semiconductor and catalyst to drive charge separation and generate electron/hole charge carriers. The growth of native oxides (SiO x ) on the surface of semiconductors during device operation induces charge carrier recombination and photodegradation, which limit the operation lifetime of PEC devices. Likewise, the commercialization of photoelectrochemical devices is hindered by the use of expensive, rare precious metal catalysts such as platinum to enhance hydrogen evolution kinetics. This work demonstrates how drop casting zinc 1T‐phase molybdenum disulfide (Zn 1T‐MoS 2 ) onto silicon nanowires (SiNWs) generates an interface that overcomes these challenges. This Zn 1T‐MoS 2 /SiNWs junction drives hydrogen evolution under acidic conditions (0.5 M H 2 SO 4 ) comparably to platinum‐modified SiNWs (Pt/SiNWs) with a positive overpotential of 164 mV at 10 mA cm −2 and low Tafel slope of 42 mV dec −1 . Compared to the bare SiNWs, the Zn 1T‐MoS 2 /SiNWs junction retains roughly 66% more photocurrent density and reduces SiO x growth by 16% after 24 h of continuous electrolysis. By developing a deep understanding of the catalyst‐semiconductor interface, photoelectrochemical devices may be effectively designed to maintain their stability over a lifetime of operation.