A novel synthesis protocol for CoO nanocatalysts and their catalytic applications

CoO spinel nanoparticles (CoO-NPs) are synthesized via a green route using neem (Azadirachta indica) leaf by an efficient and simple hot plate combustion method (HPCM). The as-prepared CoO-NPs have been characterized by well-known recognized techniques such as X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Raman spectroscopy, and vibrating sample magnetometry (VSM). CoO-NPs were investigated in various application areas; for example, a multi-lamp photocatalytic reactor was used to degrade the hazardous textile dye waste (TDW) collected from the dyeing industry. Furthermore, the antimicrobial activity of the synthesized CoO-NPs was studied against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria, in comparison to a chloramphenicol standard, and also evaluated by carrying out the catalytic hydrogenation of 4-nitrophenol and 4-nitroaniline in the presence of NaBH as a reducing agent. Noble metals have been reported earlier, but due to their high cost they needed to be replaced by a cost effective material. We have also discussed feasible mechanisms and catalytic activity of the CoO-NPs in different applications. Thus, we have proposed a novel, economic and green synthesis of CoO-NPs that is highly important in the present times for the removal of hazardous chemicals.