Efficient H₂O₂ Electrosynthesis in Acidic media via Multiscale Catalyst Optimization

Electrochemically generating hydrogen peroxide (H₂O₂) from oxygen offers a more sustainable and cost-effective alternative to conventional anthraquinone process. In alkaline conditions, H₂O₂ is unstable as HO₂ ^-, and in neutral electrolytes, alkali cation crossover causes system instability. Producing H₂O₂ 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 H₂O₂ 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%.