Chemistry of iron and copper co-doped zinc oxide: reduction and degradation of pollutants

Abstract

Stable nanomaterials, with their enhanced light absorption and synergistic effects, are crucial for the remediation of pollutants. The present study reports the synthesis of Fe and Cu co-doped ZnO nanocomposites by the auto-combustion high-temperature synthesis (AHS) approach. A stable metal oxide is formed at a temperature of 70 °C, according to TGA-DTA studies. At lower dopant concentrations, the perfect iron and copper inclusion in the ZnO lattice was visible, while at higher concentrations, an independent CuO peak formed. The porosity that occurred during the evolution of gas and dispersed nanoparticles (NPs) was clearly observed in FESEM images. EDX compositional analysis confirmed the presence of only the expected elements without any impurities in perfect proportion. Elemental mapping studies support the good dopant dispersion on the ZnO surface. A greater reduction in the PL intensity for the composites compared to that for ZnO confirms the inhibition of electron–hole recombination due to doping. The inclusion of Fe and Cu dopants into the lattice of ZnO resulted in a composite with higher light absorption properties and a redshift in the UV-vis-DRS plot when compared to the bare ZnO. Besides, the formation of ZnO–CuO and ZnO–Fe₂O₃ heterojunctions (as confirmed by HRTEM analysis) is found to be beneficial for the photon-induced electron–hole recombination inhibiting properties. The doped nanocomposites outperformed ZnO in pollutant reduction and degradation activity, indicating their higher light absorption properties and synergistic effects. As a result, the AHS approach provides a comprehensive outlook for future environmental safety applications.