Synergistic Enhancement of ZnO Nanoparticle Photocatalytic Efficiency via Silver Doping and Thermal Treatment

ABSTRACT The persistent challenge of organic pollutant degradation demands efficient photocatalysts with enhanced visible light response. This work investigates the synergistic effects of silver doping and thermal treatment on ZnO nanoparticles synthesized via co‐precipitation. Four distinct samples were prepared: pristine ZnO, Ag‐doped ZnO (5 mol%), and their thermally treated counterparts at 500°C. x‐Ray diffraction confirmed a wurtzite structure with crystallite sizes ranging from 46.0 to 84.1 nm, with improved crystallinity after thermal treatment. x‐Ray photoelectron spectroscopy (XPS) verified Ag incorporation with surface concentrations of 4.3–4.5 at%. N 2 adsorption–desorption (BET) analysis revealed that Ag‐doping increases the specific surface area from 25.7 to 38.4 m 2 /g. SEM showed morphological transformation to hexagonal particles upon annealing the Ag‐doped sample. UV‐Vis spectroscopy demonstrated band gap reduction from 3.08 eV (pristine ZnO) to 2.83 eV (Ag‐ZnO‐500). PL measurements showed significant quenching of defect emissions in Ag‐ZnO‐500. Room‐temperature ferromagnetism was observed in Ag‐doped samples, with saturation magnetization of 5.19 × 10 − 3 emu/g for the annealed sample. The thermally treated Ag‐ZnO‐500 achieved 94% methylene blue degradation within 120 min under visible light, far surpassing 52% for pristine ZnO.