In the past decade, numerous longitudinal studies have explored green chemistry and its applications in nanoparticle synthesis due to the toxicity associated with traditional methods. Among the various techniques for nanoparticle synthesis, the use of plant extracts in green synthesis has recently gained significant popularity. Green methods are particularly suitable for large-scale nanoparticle synthesis, offering faster preparation rates compared to microorganisms and the ability to produce nanoparticles in diverse sizes and shapes. Nickel oxide nanoparticles (NiO NPs) have been extensively utilized in catalysis, photocatalysis, optics, magnetism, and antibacterial applications. This review focuses on the preparation of NiO NPs using plant extracts, emphasizing their advantageous features such as the absence of contaminant release, environmental friendliness, and cost-effectiveness. Additionally, we delve into the catalytic, photocatalytic, and antibacterial applications of NiO NPs.
