Synthesis of Fe and Cu co-doped ZnO Nanocomposite (ICZ-Cs) for Catalytic Activity of Methylene Blue and 4-nitrophenol dyes from Aqueous Solution

Abstract

Stable nanomaterials with enhanced light absorption and synergistic effects are crucial for pollutant remediation. The Fe and Cu co-doped ZnO nanocomposites in this study were synthesized by the auto-combustion high-temperature synthesis (AHS) approach for the removal of methylene blue (MB) and 4-nitrophenol (4-NP) dyes from aqueous solution. . The TGA-DTA was used for thermal analysis. The result showed 490 °C as the point at which stable metal oxide is formed. XRD was used for crystalline size determination. The XRD pattern analysis not revealed the perfect iron and copper inclusion in the ZnO lattice at lower dopant concentrations and the formation of a CuO-independent peak at higher concentrations. An enhanced crystallite size increment of 10–26 nm was observed with increasing calcination time from 30 min to 3h. The porosity occurred during gas evolution, and dispersed nanoparticles were clearly observed on the FESEM images. The EDX compositional analysis confirmed the presence of only expected elements without impurities, in perfect proportion, and in accordance with the amount used during synthesis. The elemental mapping analysis confirms the good dopant distribution on the ZnO surface. FESEM/TEM provided the rod and spherical forms of the morphology. SAED and XRD results supported ZnO NP and ICZ-C15 crystallinity. From the HRTEM image and XRD pattern analysis, a minor lattice fringe difference value between ZnO and ICZ-C15 was confirmed. A greater PL intensity reduction for the composites than ZnO confirms the presence of electron-hole recombination hindrance due to doping. Dopant inclusion in the ZnO lattice resulted in the composite having higher light absorption properties and a redshift on the DRS-UV-VIS analysis when compared to bare ZnO. Besides, the formation of ZnO-CuO heterojunction is also beneficial for photon-induced electron-hole recombination hindrance properties. Because of their higher light absorption properties and synergistic effect, the doped nanocomposites outperformed ZnO in 4-nitrophenol and methylene blue catalysis. 82.25 and 99.135 of performance ICZ-C15 was obtained in reduction of MB and 4-NP respectively. 90.23% of degradation of MB was performed in ICZ-C15 as compared to ZnO, ICZ-C1, and ICZ-C10. As a result, the AHS approach provides a comprehensive outlook for future environmental safety applications.