Crystal OH mediating pathway for hydrogen peroxide production via two-electron water oxidation in non-carbonate electrolytes

Abstract

Water oxidation presents a promising avenue for hydrogen peroxide (H₂O₂) production. However, the reliance on alkaline bicarbonate electrolytes as an intermediate has limitations, such as H₂O₂ decomposition and a narrow pH effectiveness range (7–9), restricting its utility across wider pH ranges. This study unveils a crystal OH mediating pathway that stabilizes SO₄OH* as a crucial intermediate. Basic copper carbonate (Cu₂(OH)₂CO₃) tablets, commonly found on cultural relics, exhibit the capability to generate H₂O₂ in neutral or acidic non-bicarbonate electrolytes. By leveraging this crystal OH mediating strategy, considerable H₂O₂ production in Na₂SO₄ electrolytes is achievable. Notably, the H₂O₂ production rate can reach 64.35 μmol h⁻¹ at 3.4 V vs. RHE in a 50 mL 0.5 M Na₂SO₄ electrolyte. This research underscores the importance of crystal part in catalyst in catalyzing the 2e⁻ water oxidation reaction, offering valuable insights for future investigations.