Significantly improved photocatalytic H2O2 generation over PDA-modified g-C3N4 via promoting charge-carriers separation and oxygen adsorption

Recently, graphitized carbon nitride (g-C3N4) is widely used as a metal-free photocatalyst for photocatalytic hydrogen peroxide (H2O2) generation. However, its photocatalytic activity still suffers from the poor separation efficiency of charge carrier and weak adsorption ability towards dioxygen. Herein, a series of polydopamine (PDA) surface-modified g-C3N4 composites (CNPX) are successfully fabricated through a self-assembled method. The optimum material, i.e. CNP40, produced H2O2 of 69.0 μM/L under visible-light irradiation for 3 h, demonstrating 4.6-fold higher activity in comparison with the pristine g-C3N4. Meanwhile, the apparent quantum yield (AQY) reached as high as 1.91% over CNP40 under monochromatic irradiation of 420 nm, which is 6.2-fold higher than CN. It is identified that the remarkably increased photocatalytic activity is contributed to the significantly promoted charge separation and dioxygen adsorption. This present work could provide a novel environmental-friendly material for the efficient photocatalytic H2O2 production.