Cuprous oxide (Cu2O), a typical p-type semiconductor, can absorb the visible light efficiently and has a high absorption coefficient due to its narrow forbidden band. Thus, it finds potential applications in solar energy conversion and photocatalysis. However, this promising Cu2O photocathode suffers from a major issue of chemical stability and thus needs protection. To address this problem, we employed a molybdenum sulfide (MoSx) coating on Cu2O. MoSx has shown good prospects as both a protection layer and an electrocatalyst for hydrogen evolution reaction (HER) due to its excellent stability and high electrocatalytic activity. In this work, nanostructured Cu2O photocathodes were prepared by a simple electrodeposition at −0.3V versus Ag/AgCl by passing a total charge of ~4.5C. Then, the Cu2O films were spin-coated with a thin layer of MoSx and annealed in an N2 environment. The spin coating and post-processing conditions were optimized. In a separate experiment, the proton reduction performance of spin-coated MoSx/FTO electrodes was studied to decide the optimum synthesis condition using various derivatives of MoSx precursors. The photoelectrochemical measurements demonstrated higher activity for 3-layered (&lt;50 nm thick) MoSx/Cu2O photocathode fabricated at 450oC with a photocurrent on the order of 5 mA/cm2 at −0.2 V vs. RHE. Additionally, the MoSx coating improved the dark current characteristics of the Cu2O photocathode. Thus, a thin crystalline MoSx coating not only protected the Cu2O from being reduced in the electrolyte but also enhanced the catalytic activity to facilitate the proton reduction. All these findings are supported by sample characterization techniques such as Raman, XRD, SEM, XPS, and TEM studies.

Enhanced photoelectrochemical performance and stability from Cu2O photocathode protected with MoSx-catalyst

254th National Meeting (2017)

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