Phyto-mediated semiconducting n-type electrode nanomaterial: structural, compositional, and supercapacitor investigations

Abstract

Sustainable fabrication of efficient electrode is highly demandable in the present time particularly for supercapacitors. In the present work, we have functionalized zinc oxide nanoparticles (ZnO-NPs) using foliar constituents for the first time. Leaves aqueous extract of Euphorbia cognata Boiss was used as organic fuel to synthesize ZnO-NPs. The leaves extract was reacted with zinc acetate (Zn(O2CCH3)2 (H2O)2) hydro complex to obtain phyto-organic functional groups, and subsequent formation of ZnO-NPs was accomplished by thermal treatment. The X rays diffractions and energy dispersive X ray spectroscopy identified pure ZnO phase while field emission scanning electron microscopy showed spherical ZnO-NPs with particle size range of 40–65 nm. The phyto synthesized ZnO-NPs revealed direct band gap value of 3 eV via Tauc plot. The biosynthesized ZnO-NPs were, for the first time, integrated into thin film electrode by physical vapor deposition (PVD) and were subjected to cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear scan voltammetry (LSV). The fabricated ZnO thin film (ZnO-TFs) electrode exhibited the capacitance of 336.12 Fg−1 at 10 mVs−1 by CV. However, pseudocapacitive behavior was well demonstrated by LSV and CV at different scan rates. The EIS analysis illustrated very minor semi-circle arc with lower Rct and Warburg impedance by Nyquist plot indicating good electrochemical conductivity of ZnO-TFs. Overall, the results of the current study revealed that phyto-synthesized ZnO has a considerable potential for supercapacitor.