Electrooxidation of humic acids over a noble metal-free (Co,Fe)Fe2O4 catalyst for enhanced hydrogen production and water remediation

The oxygen evolution reaction (OER) remains a major energy bottleneck in water electrolysis. Replacing the OER with the electrooxidation of organic compounds offers an attractive strategy to reduce anodic overpotentials while enhancing hydrogen production. To the best of our knowledge, this work presents the first investigation of humic acids as sacrificial organic substrates to replace the OER in water electrolysis. A nanostructured, noble metal-free (Co,Fe)Fe 2 O 4 spinel catalyst was synthesized and applied to the electrooxidation of humic acids in alkaline media. The presence of humic acids significantly lowers the anodic onset potential compared to conventional OER operation, leading to enhanced current densities and hydrogen production rates. Current densities above 120 mA cm −2 were achieved at 1.8 V νs RHE, while simultaneously promoting the degradation of humic substances in aqueous media. These results demonstrate a novel approach to coupling energy-efficient hydrogen production with water treatment, opening new opportunities for the electrochemical valorization of naturally occurring organic matter.