Development of MOF-derived zinc oxide/cobalt oxide@carbon nanospheres composite for improved methanol electro-oxidation

Abstract

Developing efficient and robust electrocatalysts for methanol electro-oxidation is crucial to advancing direct methanol fuel cells (DMFCs). In this study, we investigated the catalytic properties of ZnO/Co₃O₄, derived from a metal-organic framework (MOF), and its combination with carbon nanospheres (CNS) synthesized from glucose for the electrocatalytic oxidation of methanol. The MOF-derived ZnO/Co₃O₄ was synthesized via the simple co-precipitation method and the CNS was produced using the hydrothermal method. The characterization of ZnO/Co₃O₄@CNS nanocomposite was conducted using XRD (X-ray diffraction), HR-TEM (High-resolution Transmission Electron Microscopy), FESEM (Field Emission Scanning Electron Microscopy), and ATR-IR (Attenuated Total Reflectance-Infrared) spectroscopy. These results confirmed that CNS could be incorporated into the MOF composite without disrupting its crystalline structures. By cyclic voltammetry (CV), the electrocatalytic performance was evaluated using a mixture of 1 M methanol and 1 M KOH on a modified glassy carbon electrode (GCE). Due to its more electroactive sites, high electrochemical surface area, and synergistic effect, the ZnO/Co₃O₄@CNS nanocomposite exhibited significantly enhanced electrocatalytic performance, delivering a high current density of 118.98 mA mg⁻¹ at 0.6 V with a scan rate of 50 mV/s. These outcomes highlight the potential of the ZnO/Co₃O₄@CNS nanocomposite as a leading catalyst for methanol oxidation in DMFCs.