Bimetallic persulfide nanoflakes assembled by dealloying and sulfurization: a versatile electro-catalyst for overall water splitting and Zn–air batteries

Abstract

(CoFe)(S₂)₂ nanoflakes (S–Co₅Fe₅) with graphene-like edges have been successfully developed by a facile combination of dealloying and sulfurization. Benefiting from the quantities of well-exposed edges and synergistic functionality, the atomic-level bimetallic S–Co₅Fe₅ exhibits multifunctional electro-catalytic performance toward the oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction. The S–Co₅Fe₅ catalyst as both the anode and cathode (S–Co₅Fe₅ ¦¦ S–Co₅Fe₅) needs only 1.35 V for overall water splitting in 0.1 M KOH and a cell voltage of 1.62 V can drive an electrolyzer current of 10 mA cm⁻². Besides, S–Co₅Fe₅ in a Zn–air battery (ZnAB) as the cathode (Zn plate ¦¦ S–Co₅Fe₅) possesses a high open-circuit voltage of 1.46 V, a high power density of 179 mW cm⁻² and excellent cycling stability at 10 mA cm⁻². Two ZnABs (Zn plate ¦¦ S–Co₅Fe₅) connected in series can not only power up a light-emitting diode (LED, ∼2.0 V), but also easily afford an overall water splitting electrolyzer.