Surface engineering by a novel electrochemical activation method for the synthesis of Co3+ enriched Co(OH)2/CoOOH heterostructure for water oxidation

The large-scale application of oxygen evolution reaction electrocatalysts is limited by many challenges such as sluggish kinetics, low conductivity, and instability. Remarkably, Co3+ plays a vital role in oxygen evolution catalytic process because Co3+ ions are regarded as active sites. Developing catalysts with high Co3+ content is highly promising to improve the efficiency of water oxidation. In this study, we report a novel design method through controlling pH value and potential guided by Pourbaix diagram to synthesize surface Co3+-rich catalyst. The as-prepared catalyst possesses enhanced electrode-electrolyte contact area and lower diffusion resistance. In alkaline media, this catalyst exhibits promising oxygen evolution performance, with lower onset overpotential, satisfactory overpotential, and high value of turnover frequency (TOF).