Microwave-assisted in situ growth of VO2 nanoribbons on Ni foam as inexpensive bifunctional electrocatalysts for the methanol oxidation and oxygen evolution reactions

Electrochemical water splitting and methanol (MeOH) oxidation using electrocatalysts are effective methods of producing clean energy with low pollutant emissions. In this study, low-cost vanadium oxide (VO2) electrocatalysts with nanoribbon-like structure (NRBs) were grown on Ni foam at 140, 180, and 220 degrees C using a microwave-assisted method. The electrochemical properties of the electrocatalysts fabricated at 140, 180, and 220 degrees C (VO-140, VO-180, and VO-220, respectively) were evaluated for the MeOH oxidation reaction (MOR) and oxygen evolution reaction (OER) using cyclic voltammetry (CV), linear sweep voltammetry (LSV), multi-step chronoamperometry (M-CA), and electrochemical impedance spectroscopy analyses (EIS). The VO-180 electrocatalyst presented a high current density of 224 mA cm-2 for MOR and an overpotential of 150 mV at a current density of 10 mA cm-2 for OER. The specific surface area and electron transfer rate of VO-180 were higher than those of VO-140 and VO-220. Moreover, the as-synthesized VO-180 electrocatalyst exhibited excellent MOR and OER activity and stability, suggesting its potential applications in direct MeOH fuel cells.

Automated summary

In this study, low-cost vanadium oxide (VO2) electrocatalysts with nanoribbon-like structure (NRBs) were successfully grown on Ni foam at different temperatures using a microwave-assisted method. The VO-180 electrocatalyst showed superior performance in both MeOH oxidation reaction (MOR) and oxygen evolution reaction (OER) compared to VO-140 and VO-220, with higher specific surface area and electron transfer rate. The as-synthesized VO-180 electrocatalyst exhibited excellent MOR and OER activity and stability, indicating potential applications in direct MeOH fuel cells.