Preparation of Mo2C/MWCNT catalysts and its performance in electrocatalytic oxidation of methanol

With the rapid economic development, the increasing demand for fossil fuels and the growing importance of environmental issues, the energy issue has clearly become a focal point. There is an urgent need to speed up the transformation of the energy structure, improve energy utilization and develop new green energy technologies. At the same time, the government also pays great attention to new energy and strongly supports the development of the new energy industry. Direct methanol fuel cell is a new type of energy conversion device that can directly convert chemical energy into electric energy, and has attracted great attention from researchers due to its advantages of not being limited by the Carnot cycle, high energy density, cleanliness and environmental protection. The anode catalyst of direct methanol fuel cell is the most critical component, and its catalytic performance directly affects the performance of the cell. The current commercial catalysts are mainly made of precious metals, and their commercialization is severely restricted by the high price, complicated preparation process, and susceptibility to intermediate poisoning. Carbides of Mo exhibit catalytic activities similar to those of noble metals due to their unique d-band electronic structures. In this study, the MoO2, MoO3 and Mo2C were loaded on multi-walled carbon nanotubes, respectively, the highest methanol electrooxidation activity was observed for the catalysts with Mo2C loaded on multi-walled carbon nanotubes. To study the effect of carrier surface sites on the electrocatalytic oxidation of methanol, the electrocatalytic oxidation performance of methanol was evaluated by using the Mo2C/MWCNT catalysts with one-dimensional nanostructures, which were prepared by using ammonium molybdate and multi-walled carbon nanotubes with different mass ratios as precursors. The X-ray diffractometer, scanning electron microscope, and transmission electron microscope were utilized to analyze the morphology and structure of the catalysts. The results showed that the best methanol electrocatalytic oxidation performance of the catalyst was achieved at 0.7 V (vs. Hg/HgO) with the mass ratio of precursor ammonium molybdate and MWCNT of 1:1 (Mo2C/MWCNT-1), and the current density was 185 mA/cm. The current density retained 76.19% of the initial catalytic activity after 10 h. The Mo2C was homogeneously dispersed in the walls of the multi-walled carbon nanotubes with the particle sizes of about 3～12 nm. In addition, the smaller charge transfer resistance was favorable to the methanol electrocatalytic oxidation performance.