Efficient H2O2 Electrosynthesis in Acidic media via Multiscale Catalyst Optimization

Abstract Electrochemically generating hydrogen peroxide (H 2 O 2 ) from oxygen offers a more sustainable and cost‐effective alternative to conventional anthraquinone process. In alkaline conditions, H 2 O 2 is unstable as HO 2 − , and in neutral electrolytes, alkali cation crossover causes system instability. Producing H 2 O 2 in acidic electrolytes ensures enhanced stability and efficiency. However, in acidic conditions, the oxygen reduction reaction mechanism is dominated by the inner‐sphere electron transfer pathway, requiring careful consideration of both reaction and mass transfer kinetics. These stringent requirements limit H 2 O 2 production efficiency, typically below 10–20% at industrial‐relevant current densities (>300 mA cm −2 ). Using a multiscale approach that combines active site tuning with macrostructure tuning, this work presents an octahedron‐like cobalt structure on interconnected hierarchical porous nanofibers, achieving a faradaic efficiency exceeding 80% at 400 mA cm −2 and stable operation for over 120 h at 100 mA cm −2 . At 300 mA cm −2 , the optimized catalyst demonstrates a cell potential of 2.14 V, resulting in an energy efficiency of 26%.