Visible-light Photocatalytic activity of Ag-Ce-ZnO/PANI and Ag-Ce ZnO/rGO novel nanocomposites: A comparative study

Ag, Ce co-doped ZnO-polyaniline (Ag-Ce/ZnO-PANI) and Ag, Ce co-doped ZnO-reduced graphene oxide (Ag-Ce/ZnO-rGO) were synthesized via precipitation and in-situ polymerization, an environmentally friendly process. Structural and optical properties were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), transphotoluminescence spectra (PL), and Energy Dispersive X-ray analysis (EDX). The nanocomposites exhibited crystalline structures, with ZnO, metallic silver, and cubic crystalline CeO2 identified in Ag-Ce-ZnO samples. Morphological studies revealed spherical shapes for ZnO and Ag-Ce-ZnO, while PANI displayed a fibrous structure. EDX confirmed elemental composition without impurities, and compositional mapping showed uniform dispersion. The photocatalytic degradation of Malachite green and para nitrophenol was performed using the nanocomposites under visible light irradiation. Among them, Ag-Ce/ZnO-rGO demonstrated significant photocatalytic efficiency, achieving 92% and 98% degradation of the organic contaminants, respectively. This enhanced activity can be attributed to increased specific surface area, efficient separation of photoinduced electron-hole pairs, enhanced dye adsorption, strong visible light absorption, and rapid transfer processes. Moreover, Ag-Ce/ZnO-rGO exhibited efficient reusability for five degradation cycles.