Copper doping effects on structural and photocatalytic properties of spinel ferrite nanoparticles for organophosphate pesticide removal

This study investigates copper-doped cadmium aluminum ferrite (CuxCd_1-xAl_0.2Fe_1.8O₄ (0, 0.2)) photocatalyst nanoparticles were synthesized by Sol–gel method and used for photocatalytic degradation of triazophos. XRD analysis revealed a decrease in crystallite size from 24.29 nm to 20.45 nm upon Cu doping. FTIR spectra showed peak shifts 448–437 cm⁻¹ (octahedral sites) and 520–554 cm⁻¹ (tetrahedral sites), after Cu doping. SEM indicated a more homogeneous microstructure after doping, while EDX confirmed the presence of Cu. BET analysis showed an increase in surface area from 18.45 m²/g to 47.76 m²/g. The Cu₀.₂Cd₀.₈Al₀.₂Fe₁.₈O₄ nanoparticles exhibited 91.21% triazophos degradation within 100 min under 100 W visible irradiation, compared to 63.76% for the undoped counterpart. The bandgap narrowed from 2.8 eV to 2.5 eV upon Cu doping. Scavenger analysis identified hydroxyl radicals as the primary reactive species. Adding H₂O₂ (up to 6 mM) enhanced degradation, but higher concentrations inhibited the process. The catalyst showed good reusability, with efficiency decreasing from 91.21% to 82.38% after five cycles. The enhanced photocatalytic activity was attributed to improved light absorption, charge carrier separation, and increased surface area resulting from Cu doping.