Ag NPs-assisted Fe3+-doped g-C3N4 composite to enhance photocatalytic performance†

Abstract

The photocatalytic self-Fenton system along with the surface plasmon resonance (SPR) effect of nanometals can significantly enhance the catalytic efficiency of semiconductor photocatalysts. In this work, a novel photocatalyst (Ag/Fe–g-C₃N₄) composed of Fe³⁺ doped protonated g-C₃N₄ (Fe–g-C₃N₄) and silver nanoparticles (Ag NPs) modified on its surface was successfully prepared. Furthermore, the morphology, chemical composition, and photoelectrochemical properties of the Ag/Fe–g-C₃N₄ composite photocatalyst were extensively characterized. It was found that the coordination of Fe³⁺ with the amino groups at the edge of g-C₃N₄ changed the electronic structure of the catalyst and improved the photocatalytic activity. The SPR effect of Ag NPs enhanced the light absorption efficiency and charge separation ability of the Fe–g-C₃N₄ hybrid system. The degradation efficiency of the azo dye amaranth by 3% Ag/Fe–g-C₃N₄ was as high as 98.7% under simulated sunlight irradiation for 40 min. It was 1.8 times higher than that of unmodified g-C₃N₄ (54.7%). After 5 cycles of experiments, 3% Ag/Fe–g-C₃N₄ still maintained more than 80% degradation efficiency, which has good photocatalytic activity and stability. Using sacrificial agents, we found that ˙O₂⁻ is the main active substance in degradation, followed by ˙OH and h⁺. This research provides valuable insights into the development of effective photocatalysts and has the potential to bring new perspectives to the remediation of groundwater and deep water.