Review of recent advances in plant-mediated synthesis and applications of 3d⁶- 3d¹⁰ metal oxide nanoparticles and their composites

Abstract

The aim of this review is to analytically discuss recent trends on the use of plant extract as environmental friendly technique for synthesis of 3d⁶- 3d¹⁰ metal oxide nanoparticles and composites employed for various applications. Nano-sized particles of some metal oxide and their composites have proven to be efficient for various applications in diverse fields such as wastewater treatment, luminescence, catalysis, solar cells, heat transfer systems, supercapacitors, medicine, sensors and corrosion inhibition. The nano forms of metal oxides such as oxides of Fe, Co, Ni, Cu and Zn are more valuable, excellent and proficient for various applications than their bulk counterparts owing to their specific chemical and physical characteristics. Synthetic techniques such as laser ablation, hydrothermal, sol-gel and physical grinding have been employed to synthesize these nanoparticles. Some of these techniques require much time, the use of toxic chemicals, instruments that are expensive and sophisticated skills. The use of plant extract for the synthesis of nanoparticles of transition metal oxides employed for various applications is effective, cheap, health friendly and simple. Even though agglomeration of nanoparticles synthesized via this approach is often reported, their efficacy for various applications overshadow this shortcoming which can be manipulated. Deductions from evaluation of some reports suggest that suitability of metal oxide nanoparticles for specific application depend on parameters such as crystal structure, crystalline size and morphology since metal oxide nanoparticles reported to be effective for specific application share similar attributes.