MoSe₂ nanosheets/SiNWs heterojunction-based photocathode for efficient photoelectrochemical water splitting applications

Abstract

The efficiency of a photoelectrochemical (PEC) device is governed by the solar response of the photoelectrode and kinematics of the Hydrogen evolution reaction (HER). In this study, we illustrate a simple and low-cost method for the fabrication of photocathode via spray coating of MoSe2 nanosheets (prepared by liquid exfoliation) on p-SiNWs (p-type Silicon nanowires prepared using metal-assisted chemical etching (MACE) technique) and studied their integration as a photocathode for photoelectrochemical-hydrogen evolution reaction (PEC HER) performance. The colossal photocurrent density of the resultant p-SiNWs-MoSe2 photocathode is -14.56 mA/cm2 at -1.2 V, which is appreciably larger in comparison to the bare p-SiNWs. Moreover, the charge transfer resistance (Rct) corresponding to the p-SiNWs-MoSe2 electrode is 339Ω, which is about two orders of magnitudes lower than that of p-SiNWs is attributed to the high donor density of MoSe2 nanosheets. The improvement in PEC performance is attributed to the strain at the p-SiNWs-MoSe2 interface promoted charge separation and thus reduces the kinetic barrier in water splitting process and enhances the overall hydrogen evolution reaction (HER). These results open up a scalable and effective route for implementing solar-fuel conversion at a large scale.