Boosting oxygen evolution over inverse spinel Fe-Co-Mn oxide nanocubes through electronic structure engineering

Fossil fuels are urgent to be replaced with renewable energies to achieve carbon neutrality. Intermittent renewable energies such as solar and wind could be stored in chemical bonds, such as hydrogen and carbon-containing chemicals through water and CO₂ electrolyzers respectively. Those two energy systems share a common anodic reaction, the sluggish oxygen evolution reaction (OER), which currently relies on precious noble metals to achieve a reasonable energy conversion efficiency. Herein, tuning the d-band center of Fe-based inverse spinel oxides has been achieved through compositions and morphologies engineering. Ternary Mn_0.5Co_0.5Fe₂O₄ nanocubes exhibit oxygen evolution activity superior to the benchmark RuO₂. Mössbauer and in-situ infrared spectra combined with density functional theory calculations prove that the optimized d-band center offers a balanced adsorption strength of intermediate *OOH on Mn_0.5Co_0.5Fe₂O₄ nanocubes. This work provides a promising approach to the design and synthesis of highly efficient electrocatalysts beyond oxygen evolution.