Nickel‐doped Co3O4 electrocatalyst derived from bimetal zeolitic imidazolate frameworks for the oxygen evolution reaction of electrolysis

Abstract

Oxygen evolution reaction (OER), as a multi‐step coupled anode reaction, is more sluggish in kinetics than electrocatalytic hydrogen evolution reaction (HER). In order to overcome the potential barrier in OER, it is necessary to develop high‐efficient non‐noble metal catalysts for energy utilization. In this work, several NiCo‐ZIF materials with different molar ratios of Ni and Co were prepared by doping Ni2+ in the preparation of ZIF‐67 via a simple room temperature stirring method. After that, NiCo‐ZIF was calcined at 350°C in a muffle furnace to obtain corresponding Ni‐doped Co3O4 (Ni‐Co3O4). Ni‐Co3O4 catalyst exhibits a low overpotential (η ≈ 203 mV @10 mA cm−2), a small Tafel slope (111.0 mV dec−1) and prominent stability for OER in 1 M KOH solution, which is higher than for a commercially available Ir/C electrocatalyst (η ≈ 350 mV @10 mA cm−2). The higher electrochemical performance should be largely ascribed to the introduction of oxygen vacancies resulting from the Ni doping, which leads to the improved electrochemical active surface area (122.81 mF cm−2) and the topological structure of the dodecahedron, which is in favor of the good contact area between the catalyst and the electrolyte. The design and synthesis of ZIF‐derived catalyst in this work create a significative method to prepare efficient OER electrocatalysts.