Development of Co single-atom catalysts with asymmetric structures via coordination and nano-restricted domain strategies for efficient photothermal production of H2O2

Abstract

Obtaining hydrogen peroxide (H₂O₂) with high chemical value by photothermal catalysis is a green and sustainable ideal strategy. Herein, Co single-atom loaded S-doped graphitic phase carbon nitride (Co_SA/SCN) with high photothermal catalytic activity for the preparation of H₂O₂ was prepared by a strategy of self-assembled coordination and nano-restricted domain effect. Experimental and theoretical characterizations show that Co single atoms are able to form asymmetric Co–N₃S₁ ionic bonds with S/N, which can effectively modulate the microenvironment on the SCN surface. Notably, the adsorption of O₂ on isolated Co atom sites is end-to-end, which promotes the formation of Co-μ-peroxide (Co–OOH) and effectively reduces O–O bond breakage, providing a highly selective 2e⁻ ORR pathway for H₂O₂ production. Under visible and solar irradiation, the H₂O₂ generation rates of Co_SA/SCN reached 506.1 μmol L⁻¹ h⁻¹ and 552.6 μmol L⁻¹ h⁻¹, respectively, which were 25.8 and 20.2 times higher than pristine g-CN. Femtosecond transient absorption spectroscopy (fs-TA) and theoretical calculations show that the presence of Co single atoms reduces the free energy of ∗OOH generation and enhances the ultrafast kinetic and thermodynamic processes of proton coupling and electron-hole transfer. This study introduces a new single-atom synthesis method and serves as a guide for the synthesis of catalysts with efficient photothermal catalytic H₂O₂ production activity.