Highly Selective Oxygen Electroreduction to Hydrogen Peroxide on Sulfur-Doped Mesoporous Carbon

Abstract

As a paradigm-shifting material platform in energy catalysis, precisely engineered ordered mesoporous carbon spheres emerge as supreme metal-free electrocatalysts, outperforming conventional carbon-based counterparts through synergistic structural and electronic innovations. Herein, we architecturally design vertically aligned cylindrical mesoporous carbon spheres with atomic-level sulfur doping (S-mC) that establish unprecedented performance benchmarks in the two-electron oxygen reduction reaction (2e⁻-ORR) to hydrogen peroxide. Systematic comparative studies reveal that the S-mC catalysts achieve exceptional H₂O₂ selectivity (>99%) and activity at current density of −3.5 mA cm⁻², surpassing state-of-the-art metal-free catalysts in current density. Impressively, the optimized S-mC electrocatalyst in a flow cell device achieves an exceptional H₂O₂ yield of 25 mol g_catalyst⁻¹ h⁻¹. The carbon matrix's unique sp²/sp³ hybrid network coupled with S-induced charge redistribution generates electron-deficient hotspots that selectively stabilize *OOH intermediates, as evidenced by in situ spectroscopic characterization and DFT calculations. This structural–electronic synergy endows the carbon framework with metal-like catalytic efficiency while maintaining inherent advantages of chemical robustness and cost-effectiveness. The marriage of S-doping engineering with mesoscopic pore architecture control opens a new way for developing efficient carbon-based electrocatalysts for oxygen selective reduction to H₂O₂.