Construction of Plasmonic Ag and Nitrogen-Doped Graphene Quantum Dots Codecorated Ultrathin Graphitic Carbon Nitride Nanosheet Composites with Enhanced Photocatalytic Activity: Full-Spectrum Response Ability and Mechanism Insight

The full utilization of solar energy has attracted great attention in the photocatalysis and environmental pollutant control. In this study, the local surface plasmon resonance effect of Ag nanoparticles (Ag NPs) with the upconversion property of nitrogen-doped graphene quantum dots (N-GQDs) was first combined for the formation of ternary Ag/N-GQDs/g-C3N4 nanocomposites. The prepared material presents enhanced full-spectrum light response ability, even in near-infrared (NIR) light. The experiment results disclosed that the 0.5% N-GQDs and 2.0% Ag NPs co-doped g-C3N4 show the highest photocatalytic activity, achieving 92.8 and 31.3% removal efficiency under full-spectrum light and NIR light irradiation, respectively, which was three-fold than that of pristine g-C3N4. The boosted photocatalytic activity can be attributed to the synergistic effect among the g-C3N4, N-GQDs, and Ag NPs. The g-C3N4 nanosheets can serve as the reaction matrix and support for the dispersion of N-GQDs and Ag NPs, inhibiting their agglomeration. The existence of Ag NPs and N-GQDs can promote the light absorption and transfer ability, leading to the generation of more photoinduced charges. Simultaneously, N-GQDs and Ag NPs can efficiently transfer and reserve electrons, which can accelerate the photoinduced electrons' migration, inhibiting the recombination. The comprehensive effect of the reasons mentioned above resulted in the unique photocatalytic activity of the prepared Ag/N-GQDs/g-C3N4 nanocomposites. This study provides a new strategy for the formation of highly efficient photocatalysts with broad-spectrum light response ability and the potential for realistic wastewater pollution control.