Surface catalytic effect of Ag nanoparticles and influence of dissolved oxygen on photocatalytic reduction of nitrate

Photocatalytic reduction of nitrate is a promising green strategy to remove nitrogen pollutants from water bodies. However, it is a considerable challenge to directly reduce nitrate using photogenerated electrons. In this work, a g-C₃N₄/Ag-nanoparticle composite demonstrating high catalytic activity toward nitrate is constructed using an <i>in situ</i> photodeposition method. Based on photoelectrochemical, ion chromatography and nuclear magnetic resonance characterization, Ag nanoparticles were found to exhibit strong surface catalytic activity for reducing NO₃ ^- to NO₂ ^-, while g-C₃N₄/Au-nanoparticles exhibited no photocatalytic reduction activity toward NO₃ ^-. Additionally, the effects of dissolved oxygen on the photocatalysis system of nitrate reduction are analyzed for the first time.