Plasmon–Exciton Coupling-Assisted Efficient Overall Water Splitting in Alkaline Medium Using a Plexcitonic NiO/Ni Foam Catalyst

Abstract

The rational design of bifunctional catalysts for efficient water splitting in alkaline medium under photoelectrocatalytic conditions through the coupling of photoinduced electron transfer and surface catalytic reaction holds great promise for sustainable energy conversion. The hydrogen evolution reaction (HER) in alkaline medium is challenging due to the requirement of an additional low-barrier water dissociation step along with the favorable H-adsorption on the catalytic surface. The porous NiO/Ni foam structures provide active sites for water dissociation with a high oxygen evolution reaction (OER) activity. However, their HER activity is limited, presumably due to the lack of Hadsorption sites. Here, we demonstrate a simple strategy to develop a hybrid catalyst for both alkaline HER and OER by in situ coupling of plasmonic and excitonic Au−MoS 2 hybrid nanosheets with the NiO/Ni foam. The plasmon−exciton coupling in the Au−MoS 2 hybrid is known to significantly increase the number of favorable H-adsorption sites and improve effective charge separation at the interface. By combining the low-barrier water dissociation sites of the NiO/Ni foam and the optimal hydrogen adsorption sites of plexcitonic Au−MoS 2 hybrid nanosheets, our designed Au−MoS 2 /NiO/Ni foam hybrid catalyst exhibits much superior alkaline HER and OER performances with lower overpotentials compared to the Au/NiO/Ni, MoS 2 /NiO/Ni, and bare NiO/Ni foam catalysts under both electro-and photoelectrocatalytic conditions. The plasmonic excitation with white light irradiation significantly improves the overall water-splitting performance by strong plasmon−exciton couplingassisted efficient charge transfer in the Au−MoS 2 /NiO/Ni foam hybrid catalyst. This research provides a promising strategy to enhance the alkaline water electrolysis performance in photoelectrocatalytic conditions by engineering the coupling of photoinduced electron transfer and surface-active site reactions of hybrid catalysts.