Green synthesis of ternary ZnO/ZnCo₂O₄ nanocomposites using Ricinus communis leaf extract for the electrochemical sensing of sulfamethoxazole

The quantitative measurements of different chemicals and reagents that can be found within different industrial products such as foods and drugs as one part of composition using a high surface area nano-catalytic working electrode are currently found to be a hot health related issue worldwide. The use of green synthesized nanocompoitses (NCs) modified working electrode (WE) proiveds enhanced performances as compared to the conventional electrode. This provide enhanced surface area and intern allows high charage transfer kinetics and more sensing capabilities. In the present findings, Ricinus communis leaf templated ZnO and Co3O4 NPs and, ZnO/ZnCo2O4 NCs were fabricated as a promised WE for the electrochemical sensing of Sulfamethoxazole (SMX). The synthesized NPs and NCs have been allowed for XRD, SEM-EDAX, TEM-HRTEM, SAED, UV-Vis, FTIR, CV, CA and EIS characterizations. From the XRD analysis, the average crystalline size of Co3O4, ZnO, and ZnO/ZnCo2O4 nanoparticles has been found to be 26.99, 22.44, and 22.04 nm, respectively with a good crystalline structure without any foreign phase formation. The SEM-EDAX coupled with TEM-HRTEM and SAED confirms the spherical-shaped structure having bright dot like circular spots in the center of the SAED, which proves the crystalline behavior of green NPs and NCs. The optical behavior from UV-Vis technique suggests the electronic band gap energy of Co3O4, ZnO, and ZnO/ZnCo2O4 was estimated to be 1.9, 3.2, and 3.4 eV, respectively. The role of leaf extract and formation of Zn-O, Co-O, and Zn- ZnCo2O4 confirmed from the FTIR analysis. The green formed NPs and NCs possess good electrocatalytic properties as can be confirmed from the CV, CA and EIS characterizations. The fabricated NPs and NCs were used as a best selective high surface area working electrodes for the electrochemical sensing of SMX. The study proved thatthe sensitivity and LOD of ZnO/ZnCo2O4/CPWE were found to be 9.73 mu A/mM and 91.25 mu A(-1) mu M-1 cm(-2), respectively. This is due to the immense surface modification, improvement in electrocatalytic property, enhanced charge transfer kinetics and also the relatively high surface area. Therefore, ZnO/ZnCo2O4/CPWE is highly selective with long-term cycle stability to wards SMX sensing.