Synthesis of Double Defects in g-C3N4 to Enhance the H2O2 Production by Dual-Electron O2 Reduction

In this work, the graphitic carbon nitride with -C=N defects and S-defects (N-2-SCN-4) was constructed. The H2O2 production efficiency of N-2-SCN-4 was 1423.3 mu mol g(-1) h(-1) under the visible light (lambda >= 420 nm) irradiation, which was 15.4 times that of pristine g-C3N4. The -C=N groups promote the adsorption of H+ and the S-defects provide the active center for the adsorption and activation of O-2. Furthermore, the surface morphology, microstructure, and photoelectric chemical properties of samples were investigated by a series of characterizations, and the response range of N-2-SCN-4 to visible light increases obviously. Meanwhile, the efficiency of photo-produced charge separation and the selectivity of H2O2 production were discussed in detail. The experimental and characterization results confirmed that the charge separation efficiency and the selectivity of the 2e(-) O-2 reduction reaction (ORR) were improved under the synergistic effect of the double defects. This work provides a strategy for improving the photocatalytic performance of photocatalysts.

Automated summary

In this work, a graphitic carbon nitride with -C=N defects and S-defects (N-2-SCN-4) was constructed. The H2O2 production efficiency of N-2-SCN-4 under visible light irradiation was found to be 15.4 times higher than that of pristine g-C3N4. The -C=N groups promote H+ adsorption, while the S-defects provide active centers for O-2 adsorption and activation. Surface morphology, microstructure, and photoelectric chemical properties were characterized, and the response range of N-2-SCN-4 to visible light was significantly increased. Charge separation efficiency and selectivity of H2O2 production were also discussed, showing improvement under the synergistic effect of the double defects. This work provides a strategy for enhancing the photocatalytic performance of photocatalysts.