Semiconductor photoelectrodes enable the direct conversion of sunlight into stored chemical energy. In photoelectrochemical devices, this photoconversion process relies on the junction between the semiconductor and catalyst to drive charge separation and generate electron/hole charge carriers. Recombination of charge carriers as they travel across the catalyst-semiconductor interface significantly lowers charge transfer efficiency and limits the performance of these devices. Likewise, the growth of native oxides (SiOx) on the surface of semiconductors induces charge recombination and photodegradation over extended periods of device operation. To reduce charge carrier recombination and improve photoelectrochemical device performance, noble metals, such as platinum or ruthenium, are often deposited along the semiconductor’s surface. Unfortunately, the high cost and scarcity of noble metals hinder the long-term utilization of these devices. Here, we demonstrate how drop casting zinc 1T-phase molybdenum disulfide (Zn 1T-MoS2) onto silicon nanowires (SiNWs) generates an interface that successfully overcomes these challenges. This Zn 1T-MoS2/SiNWs junction drives hydrogen evolution under acidic conditions (0.5 M H2SO4) comparably to platinum-modified SiNWs (Pt/SiNWs) with a positive overpotential of 164 mV at 10 mA/cm2 and a low Tafel slope of 42 mV/dec. Compared to the bare SiNWs, the Zn 1T-MoS2/SiNWs junction retained roughly 65.6% more photocurrent density and reduced SiOx growth by 15.96% after 24 hours of continuous electrolysis. By developing a deep understanding of the interactions that arise at the catalyst-semiconductor interface, photoelectrochemical devices may be effectively designed to maintain their stability over a lifetime of operation.

Improving the stability of silicon nanowires during photoelectrochemical hydrogen generation with Zinc 1T-phase molybdenum disulfide

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.