Polysulfide induced synthesis of a MoS 2 self-supporting electrode with wide-layer-spacing for efficient electrocatalytic water splitting.

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 MoS 2 /Ni 3 S 2 composite with wide-layer-spacing and high 1T-rich MoS 2 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 MoS 2 /Ni 3 S 2 -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 MoS 2 and Ni 3 S 2 along with the presence of ample active sulfur edge sites and few-layer, wide-layer-spacing structures of MoS 2 lead to an outstanding electrocatalytic activity. In particular, the electrodes of MoS 2 /Ni 3 S 2 -p only need a battery voltage of 1.55 V at 10 mA cm -2 . The bifunctional electrocatalyst MoS 2 /Ni 3 S 2 -p also shows excellent stability at large current densities during the electrochemical test.