Core–shell-type ZIF-8@ZIF-67@POM hybrids as efficient electrocatalysts for the oxygen evolution reaction

Abstract

Polyoxometalate (POM) nanoparticles covered with zeolitic imidazolate frameworks (ZIF-8@ZIF-67) have been repeatedly synthesized using a simple coprecipitation method, acting as highly efficient and inexpensive oxygen evolution reaction (OER) catalysts. In virtue of the synergistic effect between the POM and ZIF species, their regular architecture and their high surface area, the as-prepared ZIF-8@ZIF-67@POM hybrids exhibit remarkable OER electrocatalytic performance in a 1 M KOH electrolyte in the presence of an overpotential of only 490 mV with a current density of 10 mA cm⁻² and a low Tafel slope of 88 mV dec⁻¹. In addition, the ZIF-8@ZIF-67@POM hybrids display good long-term stability. Moreover, the ZIF-8@ZIF-67@POM catalysts have many active areas on the surface and excellent diffusion efficiency owing to their high surface areas.