S, N, and O tri-doped graphite nanosheets-based gas diffusion electrode boosts highly selective electrosynthesis of H₂O₂

Electrochemical synthesis of hydrogen peroxide (H₂O₂) via oxygen reduction reaction (ORR) is a promising environmentally friendly approach for on-site production of H₂O₂. The development of economically feasible cathodes with high activity and selectivity is of utmost importance to enable the large-scale application of the process of H₂O₂ electrosynthesis. Herein, a novel electrocatalyst of sulfur, nitrogen, and oxygen tri-doped graphite nanosheets (SNOGNSs) was developed, which exhibited the selectivity of up to 97.4 % for the electrosynthesis of H₂O₂, significantly higher than that of flake graphite (FG, 51.4 %), OGNSs (72.8 %) and NOGNSs (90.9 %). The gas diffusion electrode (GDE) was fabricated using SNOGNSs as catalysts, and the accumulation of H₂O₂ reached 732.8–1044.4 mg/Lh⁻¹ at 0.3–0.5 A electrolytic current. The mechanism of the synergistic enhancement of two-electron ORR by S, N, and O tri-doping was revealed utilizing density functional theory (DFT) calculations. This work offers a suitable alternative for on-site clean production of H₂O₂ that can be applied in electrochemical advanced oxidation processes.