Ag-modified, Fe, and cu-doped ZnO/g-C3N4 nanocomposite photocatalyst with enhanced activity toward degradation of pollutant and hydrogen evolution

Abstract

In this paper, Ag-loaded and Cu and Fe-doped ZnO/g-C₃N₄ nanocomposites were produced by a chemical precipitation method. The photocatalytic performance of these nanocomposites was assessed by degrading methylene blue (MB) and producing hydrogen via water splitting under visible light illumination. The incorporation of Cu, Fe, and Ag into the photocatalyst's structure was confirmed by multiple findings, which also provided insights into its features that are essential for enhancing photocatalytic performance. The successful integration of Ag and ZnO into the g-C₃N₄ was confirmed by transmission electron microscope (TEM) analysis. Optical and electrochemical characteristics results have illustrated that creating a heterostructure between ZnO and g-C₃N₄ with effects of Ag loading and Cu and Fe doping enhanced charge separation, higher photocurrent density, and reduced band gap to 2.73 eV for the Ag-loaded sample. The best photocatalytic activity was demonstrated by the Ag-loaded ZnO/g-C₃N₄ nanocomposite, with a complete MB photodegradation after 180 min. Mott-Schottky analysis combined with scavenging experiments reveals that superoxide radicals are pivotal in driving photocatalytic activity. These results therefore confirm that the addition of Ag changes the charge transfer path in the ZnO/g-C₃N₄ nanocomposite from a conventional type II mechanism to a configuration of Z-scheme. The hydrogen evolution of the Ag-loaded nanocomposite was 1566 μmol/g.h, higher than those of nanocomposites doped with Cu and Fe. Ag appears to be more significant than Fe and Cu in improving the nanocomposite's characteristics for photocatalytic functions in environmental remediation and renewable energy generation.