Polysulfide induced synthesis of a MoS2 self-supporting electrode with wide-layer-spacing for efficient electrocatalytic water splitting

Abstract

Efficient non-noble metal bifunctional electrocatalysts can increase the conversion rate of electric energy in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, a ball & sheet MoS₂/Ni₃S₂ composite with wide-layer-spacing and high 1T-rich MoS₂ is assembled on nickel foam (NF) via a two-step solvothermal method with polymeric sulfur (S-r-DIB) as the sulfur source. The obtained material serves as both the cathode and the anode toward overall water splitting in an alkaline electrolyte. The results proved that the interpenetration of MoS₂/Ni₃S₂-p with a ball and sheet structure increased the material active surface area and exposed more catalytic active sites, which contributed to the penetration of solution and the transfer of charge/hydrion. Meanwhile, two different semiconductors of MoS₂ and Ni₃S₂ along with the presence of ample active sulfur edge sites and few-layer, wide-layer-spacing structures of MoS₂ lead to an outstanding electrocatalytic activity. In particular, the electrodes of MoS₂/Ni₃S₂-p only need a battery voltage of 1.55 V at 10 mA cm⁻². The bifunctional electrocatalyst MoS₂/Ni₃S₂-p also shows excellent stability at large current densities during the electrochemical test.