Green Synthesis of ZnO Nanoparticles and Ag-Doped ZnO Nanocomposite Utilizing Sansevieria trifasciata for High-Performance Asymmetric Supercapacitors.

This study provides a comprehensive analysis of a biofabricated nanomaterial derived from Sansevieria trifasciata root extract, evaluating its structural, morphological, and optical properties for use in asymmetric supercapacitors. The nanomaterial comprises pristine ZnO nanoparticles (ZnO NPs) and a 1% Ag-doped ZnO nanocomposite (Ag@ZnO NC), synthesized through a green-assisted sol-gel autocombustion method. Employing techniques such as X-ray diffraction, ultraviolet-visible near-infrared, scanning electron microscopy-energy-dispersive X-rayspectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy, the study confirms a hexagonal wurtzite structure and nanocrystallites with spherical and hexagonal shapes (30 nm). Optical analysis reveals a red shift in the band gap with Ag doping, indicating improved conductivity. The material shows potential applications in solar cells, optoelectronics, spintronics, wastewater treatment, and high-performance asymmetric supercapacitors. Raman spectra validate the wurtzite phase and identify intrinsic defects. Electrochemical tests demonstrate remarkable supercapacitive behavior with a 94% capacitance retention after 10,000 cycles, highlighting its promise as advanced asymmetric supercapacitors.