Mechanistic insights into Charge-Driven Photocatalytic Degradation of Phenols over Green-assembled Ag@ZnHCF-rGO nanocubes

Abstract

Hydroquinone (HQ) and 4-Nonylphenol (4-NP) are toxic environmental pollutants used extensively in cosmetics and other industries and pose harmful effects on human health and the environment. Therefore, for their removal, Ag@ZnHCF-rGO nanocomposite was successfully synthesized via a co-precipitation approach using A. indica plant leaves extract to ensure eco-friendliness. Further characterisation reveals that the synthesized nanocomposite possesses superior photocatalytic activity in comparison to bare Ag@ZnHCF, ZnHCF and rGO due to enhanced surface area and charge (-47.2 mV), tuned band gap (1.8 eV) and enhancement in the lifetime of photogenerated charges, reducing the recombination probability. At an optimized condition, Ag@ZnHCF-rGO eliminates 4-NP (95% in 270 min) and HQ (98% in 180 min) in sunlight, following first-order kinetics. Also, through the use of a radical trapping experiment, the major contribution of hydroxyl radicals in the removal of contaminants was identified. The environmentally friendly Ag@ZnHCF-rGO composite is stable, reasonably priced, and an outstanding photocatalyst that can be reused upto 8 cycles. It also works well for treating different wastewater samples spiked with both the pollutants and real-life HQ samples from cosmetic whitening creams, as analysed using the HPLC method. For the purpose of eliminating toxic organic environmental pollutants as well as promoting further research and development, this study emphasizes the need to combine green synthesis techniques with cutting-edge photocatalytic materials.