Unlocking efficient methanol electro-oxidation in alkaline medium with non-stoichiometric 3D sphere-like Cu3Mo2O9@CoMoO4 heterostructure

Abstract

In order to unlock the full potential of direct methanol fuel cells (DMFCs), there is a pressing need for the development of cost-effective catalysts that don't rely on precious metals. Within this context, we have successfully synthesized a non-stoichiometric three-dimensional (3D) sphere-like Cu3Mo2O9@CoMoO4 heterostructure using a straightforward two-step hydrothermal process. A range of analytical techniques was utilized to explore the physical and chemical properties of this Cu3Mo2O9@CoMoO4 in comparison to their constituents' parts, one-dimensional (1D) rod-like Cu3Mo2O9 and CoMoO4 microstructures. X-ray photoelectron spectroscopy (XPS) was employed for the quantitative assessment of the non-stoichiometric composition of elements such as Cu, Co, and Mo within the heterostructure. This outcome was additionally corroborated by data obtained through analysis using field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS). The heterostructure showed highly porous characteristics and displayed a large surface area of 42.54 m2 g−1 compared to Cu3Mo2O9 and CoMoO4. This configuration yields a notably preeminent current response for methanol electro-oxidation (MOR), reaching 202.8 mA cm−2 at a scan rate of 50 mV s−1 within the voltage range of 0.0–0.7 V (vs. Hg/HgO). In comparison, both Cu3Mo2O9 and CoMoO4 exhibit lower methanol electro-oxidation currents of 154.9 mA cm−2 and 120 mA cm−2, respectively. After examination by chronoamperometry for 10 h, the Cu3Mo2O9@CoMoO4 exhibited good stability performance. This research illustrates that the synergistic effects between Cu3Mo2O9 and CoMoO4 within Cu3Mo2O9@CoMoO4 heterostructure can significantly boost electrocatalytic capabilities. This enhancement opens extensive avenues for advancing cost-effective electrocatalyst materials for the broader advancement of efficient MOR processes.