Control of carbon vacancies in g-C3N4 photocatalyst via wood pyrolysis induced etching strategy.

[Display omitted] • Tunable carbon vacancy g-C 3 N 4 is synthesized by wood pyrolysis induced etching. • CO x gas effectively tailors physicochemical and photoelectric properties of g-C 3 N 4. • Small particle sizes and amorphization transition in phase structure is achieved. • This photocatalyst exhibits nearly 20 times improvement in H 2 evolution. Post-thermal treatment is a widely employed technique for the fabrication of graphitic carbon nitride (g-C 3 N 4) with thin-layered, porous and defect-rich structures for photocatalytic hydrogen evolution. Here, the synthesis of catalysts is assisted with wood pyrolysis, which triggers an etching on g-C 3 N 4 by released trace carbon oxides gases. Specifically, a nickel foam is used as the substrate to hold a piece of pine wood on top of bulk g-C 3 N 4 , thereby preventing interfacial structural damage and introduction of impurities in a conventionally used solid state mixing process. Such a multicomponent atmosphere results g-C 3 N 4 with tunable carbon vacancies (TCCNx) and small particle sizes, and therefore a large specific surface area is obtained. The as-prepared TCCNx exhibits an improved photocatalytic hydrogen evolution rate of 3703 μmol·g−1·h−1, outperforming the bulk g-C 3 N 4 by ∼20 folds under visible light (λ > 420). The reason for enhanced photocatalytic performance is ascribed to a favorable optical property, rapid charge carrier separation, and efficient charge transfer processes. This unique top-down etching strategy provides valuable insights for designing efficient polymer photocatalysts with controllable properties. [ABSTRACT FROM AUTHOR]