CoCeO 2 Nanoparticles: Green Synthesis, Characterization, Photocatalytic Degradation of Organic Pollutants, Catalytic Reduction of 4‐Nitrophenol, and Antimicrobial Activity

ABSTRACT In this research study, we report the green synthesis of CoCeO 2 nanoparticles using the fruit extract of Averrhoa carambola . It produces an environmentally benign alternative by utilizing the bioactive phytochemicals found in A. carambola fruit, which function as natural reducing and stabilizing agents. The characterization using X‐ray diffraction (XRD), EDX, field emission scanning electron microscopy (FESEM), high‐resolution transmission electron microscopy (HRTEM), FTIR, UV–vis spectroscopy, and BET reveals the spherical nanoparticles with crystallite size 13.6 nm and a 44.70 m 2 /g surface area. The photocatalytic, catalytic, and antimicrobial study of synthesized CoCeO 2 nanoparticles is investigated. The CoCeO 2 nanoparticles show excellent photocatalytic activities by 99% breakdown of Victoria blue dye in 9 min. The CoCeO 2 nanoparticles act as an efficient catalyst for the reduction of environmentally hazardous 4‐nitrophenol within 12 min. The CoCeO 2 nanoparticles exhibited strong antibacterial activity, as evidenced by inhibition zones against Gram‐positive bacteria (17.2 ± 0.54 mm for Staphylococcus aureus , 19.7 ± 0.60 mm for Bacillus subtilis ) and Gram‐negative bacteria (18.1 ± 0.57 mm for Escherichia coli , 13.0 ± 1.44 mm for Pseudomonas aeruginosa ), as well as antifungal activity against Candida albicans by showing 16.4 ± 0.29 mm of inhibition zone. CoCeO 2 nanoparticles represent a promising candidate for photocatalytic, catalytic, and pharmaceutical‐related applications. This green synthesis is simple, scalable, and environmentally benign.