Binder-free bifunctional SnFe sulfide/oxyhydroxide heterostructure electrocatalysts for overall water splitting

Developing robust non-noble catalysts towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is vital for large-scale hydrogen production from electrochemical water splitting. Here, we synthesize Sn- and Fe-containing sulfides and oxyhydroxides anchored on nickel foam (SnFeS_xO_y/NF) using a solvothermal method, in which a heterostructure is generated between the sulfides and oxyhydroxides. The SnFeS_xO_y/NF exhibits low overpotentials of 85, 167, 249, and 324 mV at 10, 100, 500 and 1000 mA cm^?2 for the HER, respectively, and a low overpotential of only 281 mV at 100 mA cm^?2 for the OER. When it serves as both anode and cathode to assemble an electrolyzer, the cell voltage is only 1.69 V at 50 mA cm^?2. The sulfides should be the efficient active species for the HER, while the oxyhydroxides are highly active for the OER. The unique sulfide/oxyhydroxide heterostructure facilitates charge transfer and lowers reaction barrier, thus promoting electrocatalytic processes.