Boosting O2 Reduction and H2O Dehydrogenation Kinetics: Surface N‐Hydroxymethylation of g‐C3N4 Photocatalysts for the Efficient Production of H2O2

Abstract g‐C3N4 photocatalysis is a safe and green approach for H2O2 production, but the activity of pristine g‐C3N4 photocatalysts is unsatisfactory. At present, most of the modifications on g‐C3N4 photocatalysts for H2O2 production have focused on thermodynamic processes, few have considered the kinetic aspects. Herein, the surface N‐hydroxymethylation of g‐C3N4 photocatalysts for the efficient kinetic production of H2O2 is reported. Through the reaction of formaldehyde with the amino moieties (–NH2) on the g‐C3N4 surface, N‐hydroxymethyls groups (‐NH‐CH2‐OH) are introduced on typical g‐C3N4 photocatalysts. Relative to the pristine g‐C3N4 photocatalysts, the modified g‐C3N4 photocatalysts have over 1280% higher activity for H2O2 production in pure water system, and impressive solar‐to‐chemical conversion efficiency. The experimental investigations and theoretical calculations reveal that the introduction of ‐NH‐CH2‐OH on the g‐C3N4 photocatalysts does not change their morphology, light absorption intensity and edges, band positions, charge separation and transfer properties, but markedly improved the H2O dehydrogenation and O2 adsorption properties of g‐C3N4. As a result, the reduction kinetics of O2 to H2O2 on the g‐C3N4 photocatalysts with ‐NH‐CH2‐OH is more energetically favorable. This work provides a useful reference and inspiration to achieve the effective modification of g‐C3N4 or other metal‐free photocatalysts from the kinetic perspective.