Metal–Organic Framework-Derived FeCo<sub>2</sub>S<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> Heterostructure with Enhanced Electrocatalytic Performance for Oxygen Evolution and Hydrogen Evolution Reactions
M. Amin Bhat, Kowsar Majid
Abstract
Herein, a versatile FeCo 2 S 4 /Co 3 O 4 heterostructure consisting of zeolitic imidazolate framework ZIF-derived Co 3 O 4 and FeCo-layered double hydroxide-derived Fe-doped Co sulfide is employed for the all-important alkaline full water splitting process. The heterostructure is prepared by combining pyrolysis and hydrothermal/solvothermal processes. The synthesized heterostructure possesses an electrocatalytically rich interface and renders excellent bifunctional catalytic performance. An overpotential of 139 mV for a standard cathodic current of 10 mA cm –2 with a low Tafel slope of 81 mV dec –1 is recorded for the hydrogen evolution reaction. An overpotential of 210 mV is observed for an anodic current of 20 mA cm –2 with a low Tafel slope of 75 mV dec –1 recorded for the oxygen evolution reaction. The full-symmetric two-electrode cell was capable of generating a current density of 10 mA cm –2 at a cell potential of 1.53 V and a low onset potential of 1.49 V. The symmetric cell architecture exhibits remarkable stability, as a negligible potential increase is observed for continuous water splitting over a 10 h period. With the reported performance, the heterostructure compares well with most of the excellent reported catalysts for alkaline bifunctional catalysts.