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 x O y /NF) using a solvothermal method, in which a heterostructure is generated between the sulfides and oxyhydroxides. The SnFeS x O 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. The heterostructure between sulfides and oxyhydroxides in the SnFeS x O y /NF facilitates charge transfer and lowers reaction barrier, thus promoting electrocatalytic HER and OER processes. [Display omitted] • SnFeS x O y /NF shows low HER overpotentials of 85 and 324 mV at 10 and 1000 mA cm−2, respectively. • SnFeS x O y /NF shows overpotential of only 281 mV at 100 mA cm−2 for the OER. • SnFeS x O y /NF-based electrolyzer needs 1.69 V to deliver 50 mA cm−2. • Heterostructure between sulfides and oxyhydroxides improves the electrocatalytic activity. [ABSTRACT FROM AUTHOR]