Non-Metal Silicon Single-Atom Catalysts with Unsymmetrically Tetradentate O3N1 Moiety Enabling Ampere-Level H2O2 Electrosynthesis

Abstract

The development of efficient and stable catalysts for scalable and sustainable hydrogen peroxide (H₂O₂) electrosynthesis via two-electron oxygen reduction reaction (2e-ORR) is of great significance to replace the high-pollution anthraquinone oxidation process. Herein, O/N dual-coordinated silicon (Si) single-atom catalysts (SACs) uniformly immobilized on N-doped graphene (SiO₃-NC) are successfully synthesized using silicate as Si dopant via controllable solvothermal and nitridation processes. In the synthesize reaction, Si centers convert from Si–O₃ planar triangle to unsymmetrical Si–O₃N₁ tetrahedron, which effectively modify the electronic distribution of the carbon matrix, providing high-density active sites for electrocatalytic H₂O₂ production. SiO₃-NC catalysts achieve industrial-relevant current densities for H₂O₂ production with a record-high productivity of 63.69 mol h⁻¹ g_cat.⁻¹, while maintaining exceptional Faradaic efficiencies and stability. In situ spectroscopic studies and theoretical calculations uncover that the unsymmetrically Si–O₃N₁ configuration acts as an active center, which affords near-optimal binding strength for OOH* adsorption and accelerates the kinetics of H₂O₂ formation, thus promoting 2e-ORR process.