GREEN SYNTHESIS OF TRANSITION METAL OXIDE NANOPARTICLES FOR HIGH-PERFORMANCE ELECTROCHEMICAL ENERGY STORAGE APPLICATIONS
Keywords:
green synthesis, transition metal oxides, nanoparticles, electrochemical energy storage, supercapacitors, lithium-ion batteries, sodium-ion batteries, plant extracts, microbial synthesis, specific capacitance, cycle stability, biogenic reductionAbstract
The escalating demand for efficient, eco-friendly energy storage systems has driven the adoption of green synthesis methods for transition metal oxide (TMO) nanoparticles, replacing conventional toxic chemical routes with biogenic approaches using plant extracts, microbes, and algae. This review explores the synthesis, characterization, and electrochemical performance of TMOs such as MnO₂, NiO, Co₃O₄, Fe₂O₃, and ZnO, highlighting their applications in supercapacitors (specific capacitances up to 2000 F/g), lithium-ion batteries (capacities >1000 mAh/g), and sodium-ion batteries. Green routes leverage natural reducing agents (polyphenols, alkaloids) for controlled nanoparticle morphology (spheres, rods, sheets), yielding high surface area (50–300 m²/g), enhanced conductivity via doping, and superior cycle stability (>90% retention after 5000 cycles). Mechanisms involve microbial extracellular enzymes and plant-mediated reduction, offering scalability and reduced environmental impact. Challenges include batch variability and purity, addressed through optimized protocols and hybrid composites (e.g., TMO-graphene). The integration of these nanomaterials promises sustainable, high-performance devices for electric vehicles, renewables, and portable electronics, aligning with global green chemistry goals
