High-effective generation of H2O2 by oxygen reduction utilizing organic acid anodized graphite felt as cathode

Abstract

Achieving high catalytic performance with the lowest cost possible cathode material is critical for electrocatalytic synthesis of H2O2 by oxygen reduction reaction. In this work, we describe a method of preparing highly active yet stable graphite felt electrocatalysts containing ultrahigh-loading oxygen content by using organic acid anodic modification. The results show that modified graphite felt surface was more hydrophilic and introduced a large amount of defect sites and oxygen-containing groups. Moreover, the influence of mass oxalic/citric acid ratio and oxidation time of graphite felt cathode were investigated. As a result, H2O2 electrogeneration was 1.6 times as much as that of virgin graphite felt counterpart at the mass oxalic/citric acid ratio of 2:1 oxidation for 40 min. However, overoxidation also impaired the electrical production of H2O2 due to decarboxylation. Finally, the effect of cathode potential and reaction pH on graphite felt cathode was optimized. As for the modified graphite felt, the maximum accumulation rate of H2O2 reached 4.5 mg h−1 cm−2 at the conditions of − 0.85 V (SCE), 0.4 L min−1 O2 flow rate and pH = 3. In addition, it kept a stable performance for electrochemical generation of H2O2 during 8 cycles.