Nitrogen-Vacancy Defective Carbon Nitride Modified Graphite Felt Cathode for Efficient Electrochemical Synthesis of Hydrogen Peroxide
Electrochemical two-electron oxygen reduction (2e−ORR) for hydrogen peroxide (H2O2) synthesis faces challenges of low cathodic catalytic efficiency and complex catalyst preparation. This study prepared nitrogen-vacancy (Nv) rich carbon nitride via one-step pyrolysis, composited with carbon nanotubes (CNT), and loaded onto graphite felt (GF) to fabricate a non-precious metal gas diffusion electrode Nv-C3N4-CNT/GF. The electrode exhibited a three-dimensional fibrous skeleton with interconnected micro-nano hierarchical pores, facilitating efficient electron transport. Electrochemical impedance spectroscopy revealed a low charge transfer resistance of 13.26 Ω, indicating superior electrocatalytic activity and charge transfer efficiency. Single-factor experiments and response surface methodology (RSM) optimization determined optimal conditions: calcination temperature 300 °C, catalyst mass ratio 3:1, Nv-C3N4-CNT loading 0.1 g, current density 40 mA·cm−2, pH 7, and aeration rate 0.1 L·min−1. Under these conditions, H2O2 accumulation reached 1622.73 mg·L−1 after 90 min, which was 1.3 and 1.5 times higher than g-C3N4-CNT/GF and CNT/GF electrodes, respectively. Stability tests showed that after 6 cycles, H2O2 production remained at 1400.52 mg·L−1, and within 960 min, the maximum production reached 2014.04 mg·L−1 with a highest Faradaic efficiency of 54.86%. These results demonstrate the electrode's potential for cyclic use. This study provides a new approach for developing efficient, low-cost electrodes for electrosynthesis of H2O2, offering a reference for green H2O2 production.