Effect of H₂O₂ Concentration on the Electrochemical H₂O₂ Oxidation and Reduction Reactions on the Pt/C Catalyst in Acid Solutions

Hydrogen peroxide (H 2 O 2 ) oxidation reaction (HPOR) and reduction reaction (HPRR) play vital roles in various innovative H 2 O 2 -related electrochemical energy conversion systems. Understanding the interactions of H 2 O 2 with catalyst surfaces and its impact on HPOR/HPRR activity at the working potential is essential for the further development of these H 2 O 2 -related systems. Herein, we investigate the effects of the H 2 O 2 concentration on the HPOR/HPRR activities for Pt/C catalysts and reveal the complex influence of H 2 O 2 on the oxygen coverage of the Pt surface at various potentials. In addition, we find that the apparent number of electrons transferred at the HPRR potential differs from its theoretical value, which is attributed to the release of unreacted hydroxyl radicals via the chemical dissociation of H 2 O 2 at the Pt surface. These findings expand our understanding of the interactions of H 2 O 2 and Pt/C catalysts at the electrochemical interface for HPOR and HPRR, providing valuable insights into the underlying reaction mechanisms.