Tuning active sites of carbon nitride using NiO nanoparticles for efficient photocatalytic generation of hydrogen peroxide

Abstract

The use of solar photocatalysis to produce H2O2 as a new strategy alternative to the anthraquinone method, is less resource intensive and more environmentally friendly. In this study, carbon nitride (CN) loaded with NiO nanoparticles (CN-NiO) was used as photocatalyst for the generation of H2O2 through two electron oxygen reduction reactions (ORR). The existence of NiO nanoparticles improves both the photoactivity and selectivity of the carbon nitride towards two electron ORR. CN-NiO photocatalyst reaches 86 % selectivity for 2e− ORR, and a yield of 4054.1 μmol g−1h−1 for H2O2 generation under simulated sunlight, which is 2.7 times of that for bare CN. NiO nanoparticles promote the separation efficiency of photogenerated electrons and holes in photocatalysts, and also serve as adsorption sites for O2, enhancing the adsorption of O2. Additionally, DFT calculations show that the loading of NiO nanoparticles greatly reduces the energy barrier for the activation of *O2 to *OOH, which facilitates the efficient 2e− ORR photocatalysis. This study may advance knowledge regarding the function of metal oxide nanoparticles in the photocatalytic synthesis of H2O2.