Effect of Photodeposited Noble Metal Nanoparticles on the Sacrificial-Agent-Free H₂O₂ Photosynthesis Performance of g-C₃N₄

Photodeposition of noble metal nanoparticles is one of the effective strategies to enhance the photocatalytic activity of g-C 3 N 4, but there are few reports about its application to improve the photocatalytic production of hydrogen peroxide (H 2 O 2 ) by g-C 3 N 4 . In this work, different types and surface states of noble metal (Pt, Rh, Ru, Au, and Ag) nanoparticles were loaded on the surface of g-C 3 N 4 through photodeposition. Based on their decomposition activity to H 2 O 2, it was found that the weak adsorption between noble metals (such as metallic Ag, metallic Au, and negatively charged Au) and H 2 O 2 was an important factor in inhibiting H 2 O 2 decomposition. In addition, compared with metallic Au and metallic Ag, negatively charged Au was more conducive to O 2 adsorption and activation. More importantly, besides the inhibition of carrier recombination benefiting from cocatalyst loading, the surface plasmon resonance effect of Au facilitated more electrons to participate in the reduction reaction. Thereby, the g-C 3 N 4 loaded with negatively charged Au obtained the highest H 2 O 2 concentration (16.98 μM in the first hour) in the absence of sacrificial agents through a two-step single-electron O 2 reduction reaction pathway.