Boosting O2 Reduction and H2O Dehydrogenation Kinetics: Surface N-Hydroxymethylation of g-C3N4 Photocatalysts for the Efficient Production of H2O2
g -C 3 N 4 photocatalysis is a safe and green approach for H 2 O 2 production, but the activity of pristine g -C 3 N 4 photocatalysts is unsatisfactory. At present, most of the modifications on g -C 3 N 4 photocatalysts for H 2 O 2 production have focused on thermodynamic processes, few have considered the kinetic aspects. Herein, the surface N -hydroxymethylation of g -C 3 N 4 photocatalysts for the efficient kinetic production of H 2 O 2 is reported. Through the reaction of formaldehyde with the amino moieties (–NH 2 ) on the g -C 3 N 4 surface, N -hydroxymethyls groups (-NH-CH 2 -OH) are introduced on typical g -C 3 N 4 photocatalysts. Relative to the pristine g -C 3 N 4 photocatalysts, the modified g -C 3 N 4 photocatalysts have over 1280% higher activity for H 2 O 2 production in pure water system, and impressive solar-to-chemical conversion efficiency. The experimental investigations and theoretical calculations reveal that the introduction of -NH-CH 2 -OH on the g -C 3 N 4 photocatalysts does not change their morphology, light absorption intensity and edges, band positions, charge separation and transfer properties, but markedly improved the H 2 O dehydrogenation and O 2 adsorption properties of g -C 3 N 4 . As a result, the reduction kinetics of O 2 to H 2 O 2 on the g -C 3 N 4 photocatalysts with -NH-CH 2 -OH is more energetically favorable. This work provides a useful reference and inspiration to achieve the effective modification of g -C 3 N 4 or other metal-free photocatalysts from the kinetic perspective.
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