UC Berkeley

Integration of molybdenum disulfide (MoS2) onto high surface area photocathodes is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction (HER). Semiconductor nanowires (NWs) are beneficial for use in photoelectrochemistry because of their large electrochemically available surface area and inherent ability to decouple light absorption and the transport of minority carriers. Here, silicon (Si) NW arrays were employed as a model photocathode system for MoS2 wrapping, and their solar-driven HER activity was evaluated. The photocathode is made up of a well-defined MoS2/TiO2/Si coaxial NW heterostructure, which yielded photocurrent density up to 15 mA/cm2 (at 0 V vs. the reversible hydrogen electrode (RHE)) with good stability under the operating conditions employed. This work reveals that earth-abundant electrocatalysts coupled with high surface area NW electrodes can provide performance comparable to noble metal catalysts for photocathodic hydrogen evolution.