Mechanistic insights into ZIF-67-derived Ir-doped Co3O4@N-doped carbon hybrids as efficient electrocatalysts for overall water splitting using in situ Raman spectroscopy

Abstract

Developing highly active bifunctional electrocatalytic nanomaterials toward overall water splitting (OWS) is required to address the energy crisis via manufacturing clean hydrogen (H2) fuel. Herein, we demonstrate the rational synthesis of a bifunctional electrocatalyst based on an Ir-doped Co3O4-anchored N-doped carbon (Ir-Co3O4@NC) hybrid for the OWS. Zeolitic imidazolate framework-67 (ZIF-67) polyhedrons was synthesized by a novel pulsed laser ablation in liquid (PLAL) technique. Subsequently, ZIF-67 polyhedrons were employed as a self-template and cobalt precursor to develop the Ir-Co3O4@NC hybrid using ion exchange and calcination approaches. Owing to the availability of more active metal sites, effective charge transport, huge surface area, and good conductivity, the Ir-Co3O4@NC hybrid displayed excellent bifunctional catalytic activity toward the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The in situ Raman spectroscopy results demonstrated the creation of Co(OH)2 species for the HER and CoOOH and Ir-O species for the OER as active intermediates at the electrode–electrolyte interfaces. As a result, the fabricated alkaline water electrolyzer with the Ir-Co3O4@NC∥Ir-Co3O4@NC exhibited a low cell potential of 1.62 V at 10 mA cm−2 and superior catalytic durability. Our work paves the way for the practical applications of effective bifunctional electrocatalysts for hydrogen production.