Tuning the ratio of Bi/Bi₂O₃ in Bi/PNC nanosheet for high-efficiency electrosynthesis hydrogen peroxide

Electrocatalytic two-electron oxygen reduction reaction (2e⁻ ORR) is a promising method for producing green and sustainable H₂O₂ but lacks high selectivity and yields electrocatalysts. And it is critical to develop catalysts that meet industrial demands. Herein, we report the different ratios of Bi⁰/Bi³⁺ supported on a phosphorus, nitrogen, and carbon nanosheet (Bi/PNC), which can reduce O₂ to H₂O₂ with high selectivity (up to 97.75% at 0.4 V_RHE) in 0.1 M KOH electrolyte and retain 97% selectivity even after 100 h electrolysis. Then a homemade flow-cell system was built for electrocatalytic production of H₂O₂ under an O₂ atmosphere using an improved gas diffusion electrode. The Bi/PNC-4 can achieve a high H₂O₂ yield of 2.76 mol·g_catalyst⁻¹·h⁻¹ (alkaline), 5.29 mol·g_catalyst⁻¹·h⁻¹ (neutral), and 3.50 mol·g_catalyst⁻¹·h⁻¹ (acid) in universal pH conditions. The in-situ generated H₂O₂ can function as a degradation agent for efficiently degrading pesticides and antibiotics. The outstanding selectivity and activities are attributed to the synergistic effects of Bi⁰ and Bi³⁺ that promote proton-coupled reduction of O₂ to OOH* (∆G_OOH* = 4.27 eV), and the formation of H₂O₂. The fast yield of H₂O₂ on Bi/PNC catalysts in flow-cell provides a promising path of electrocatalytic 2e⁻ ORR for practical H₂O₂ production.