Facile Synthesis of Benzene Tricarboxylate-Modified Cerium, Cobalt and Zinc Nanoparticles: Structural and Electrochemical Characterization

The research on metal oxide nanoparticles (MONs) has witnessed incredible growth in recent decades as they are promising electrode materials for multiple applications. This work presents the hydrothermal synthesis of morphologically different MONs based on zinc, cobalt and cerium metals and their modifications with benzene tricarboxylic acid (BTC) using layer-by-layer assembly method. The simple and modified nanoparticles were structurally characterized by FTIR, XRD, SEM–EDX and TGA. Modified carbon paste electrodes (1% w/w) were fabricated using each of the ZnO, ZnO–Cu–BTC, Co₃O₄, Co₃O₄–Cu–BTC, CeO₂ and CeO₂–Cu–BTC materials separately with graphite powder in paraffin oil using 3 cc portable plastic syringe. The XRD results showed 35.5, 10.8, 14.1, 11.6, 10.2 and 8.6 nm average crystal size for ZnO, ZnO–Cu–BTC, Co₃O₄, Co₃O₄–Cu–BTC, CeO₂ and CeO₂–Cu–BTC, respectively. The electrochemical characterizations of each electrode were performed by EIS as well as CV. The electrochemical surface area of electrodes fabricated from ZnO, ZnO–Cu–BTC, Co₃O₄, Co₃O₄–Cu–BTC, CeO₂ and CeO₂–Cu–BTC materials was calculated to be 153.4, 610.4, 746.1, 951.5, 161.7, and 951.8 cm², respectively. The results from EIS plots indicated that electrodes based on modified metal oxide nanoparticles experienced lesser charge transfer resistance as compared to that in simple metal oxide-based electrodes. All the results indicated that electrodes based on modified MONs provide better surface area, surface coverage, charge transfer coefficients and rate constants as compared to those for simple MON-based electrodes. It is concluded that modification of simple MONs with BTC provided smaller particles size, better structural morphology and redox reactions assistance, making them suitable for better electrochemical applications.