Efficient all p-type heterojunction photocathodes for photoelectrochemical water splitting

Abstract

In this paper, Co₃O₄ nanostructures with different morphologies (nanoparticles (NPs), nanosheets (NSs) and nanocubes (NCs)) are directly grown on an ITO substrate using a hydrothermal method. Sb₂S₃ is loaded onto Co₃O₄ to construct a Co₃O₄/Sb₂S₃ heterojunction, which is used as an all p-type photocathode for photoelectrochemical (PEC) water splitting for the first time. The specific morphologies of Co₃O₄ have been discussed in detail. The improved PEC properties of the Co₃O₄/Sb₂S₃ heterojunction are characterized. Among them, the outstanding photocurrent density of the Co₃O₄ NC/Sb₂S₃ heterojunction photocathode is accessed by −1.32 mA cm⁻² at −0.4 V vs. RHE. The enhanced PEC properties result from more active sites of specific crystal planes, excellent optical performance, suitable band gradient alignment and increased charge separation and charge transfer rate.