Electrochemically assisted preparation of defect-rich Co3O4 electrocatalysts in a water-modified deep eutectic solvent for enhanced oxygen evolution in acid

Co 3 O 4 -based electrode materials exhibit great potential for utilization as efficient catalysts for the oxygen evolution reaction (OER), especially in acidic media. However, enhancing their catalytic stability remains a crucial challenge. Herein, we present a facile electrochemical deposition approach coupled with calcination treatment to achieve in-situ growth of active Co 3 O 4 films from a deep eutectic solvent with water as the modifier. The incorporation of water optimizes the structure of fabricated Co 3 O 4 by increasing oxygen vacancies and elevating the Co 2+ /Co 3+ ratio, enabling it to sustain the OER in 0.5 M H 2 SO 4 . Impressively, the catalyst grown on Pt/Ti substrate exhibits stable operation over 125 h at 10 mA cm −2 . Attenuated total reflection-fourier transform infrared (ATR-FTIR) spectroscopy reveals that OER on the defect-rich Co 3 O 4 catalyst occurs through both lattice oxygen mediated mechanism (LOM) and adsorption evolution mechanism (AEM).