Single tungsten atom steered band-gap engineering for graphitic carbon nitride ultrathin nanosheets boosts visible-light photocatalytic H2 evolution

In this work, we report a W single atoms modified g-C3N4 porous unltrathin nanosheets (WSA-CN-PUNS) catalyst for photocatalytic H2 evolution, which is synthesized by simply calcining the polyprrole-polyoxometalate/g-C3N4 composite in air. DFT calculation and experimental results reveal that the WSA-CN-PUNS catalyst has a reduced band-gap, dopant-related defect levels and inhibited charge recombination. As a result, the WSA-CN-PUNS shows an activity of 3.02 mmol h−1 g−1 toward H2 production under visible light, which is 9.7 times higher than that of pristine g-C3N4. Meanwhile, for eliminating the waste of sacrifice agent, we demonstrate an alternative approach by coupling the photocatalytic H2 evolution with benzyl alcohol oxidation, and the H2/benzaldehyde production rates are 298.7/305.1 μmol h−1 g−1, respectively. This work not only provides a new strategy for designing high-efficiency single W atom dispersed hybrid catalyst, but also demonstrates the great potential of its practical applications in photocatalytic H2 evolution.