A New Class of Zn 1 ‐x Fe x –Oxyselenide and Zn

Abstract The scalable and cost‐effective H 2 fuel production via electrolysis demands an efficient earth‐abundant oxygen and hydrogen evolution reaction (OER, and HER, respectively) catalysts. In this work, for the first time, the synthesis of a sheet‐like Zn 1‐ x Fe x –oxyselenide and Zn 1‐ x Fe x –LDH on Ni‐foam is reported. The hydrothermally synthesized Zn 1‐ x Fe x –LDH/Ni‐foam is successfully converted into Zn 1‐ x Fe x –oxyselenide/Ni‐foam through an ethylene glycol‐assisted solvothermal method. The anionic regulation of electrocatalysts modulates the electronic properties, and thereby augments the electrocatalytic activities. The as‐prepared Zn 1‐ x Fe x –LDH/Ni‐foam shows very low OER and HER overpotentials of 263 mV at a current density of 20 mA cm −2 and 221 mV at 10 mA cm −2 , respectively. Interestingly, this OER overpotential is decreased to 256 mV after selenization and the HER overpotential of Zn 1‐ x Fe x –oxyselenide/Ni‐foam is decreased from 238 to 202 mV at 10 mA cm −2 after a stability test. Thus, the Zn 1‐ x Fe x –oxyselenide/Ni–foam shows superior bifunctional catalytic activities and excellent durability at a very high current density of 50 mA cm −2 . More importantly, when the Zn 1‐ x Fe x –oxyselenide/Ni‐foam is used as the anode and cathode in an electrolyzer for overall water splitting, Zn 1‐ x Fe x –oxyselenide/Ni‐foam(+)ǁZn 1‐ x Fe x –oxyselenide/Ni‐foam(‐) shows an appealing potential of 1.62 V at 10 mA cm −2 . The anionic doping/substitution methodology is new and serves as an effective strategy to develop highly efficient bifunctional electrocatalysts.