Temperature-Induced Lattice Distortion in ZnCo₂O₄ for Improving Electrocatalytic Oxygen Evolution Reaction

Spinel oxides exhibit considerable potential as electrocatalysts for the oxygen evolution reaction (OER) owing to their diverse surficial composition and electronic structure. Engineering the spin state of metal ions has been acknowledged as an effective approach to improving OER activity. However, comprehensively understanding the intricate connection between the structure and activity still poses challenges. In this study, we present a temperature-induced lattice distortion strategy to manipulate the electronic structure of spinel ZnCo2O4, resulting in remarkable performance toward OER. Experimental findings demonstrate that calcination temperature can precisely control the distortion of the CoO6 octahedra and thus manipulate the spin state of Co3+ ions. Magnetic analysis reveals that ZnCo2O4 calcined at 300 degrees C consists of Co3+ ions with 64.4% in high-spin and 35.6% in low-spin states, possessing a favorable spin configuration and thus exhibiting optimal OER activity. We believe that the implementation of this strategy can provide valuable insights for developing advanced spinel oxide electrocatalysts based on spin-state engineering.