MOF-derived Co embedded into N-doped nanotube decorated mesoporous carbon as a robust support of Pt catalyst for methanol electrooxidation

Abstract

The fabrication of a Pt-based catalyst with high activity and stability for methanol electrooxidation is both of vital importance and challenging for direct methanol fuel cells. Herein, a catalyst support based on Co embedded into N-doped nanotube decorated mesoporous carbon (Co@NCNTs-MC) derived from metal-organic frameworks (MOFs) was synthesized by a pyrolysis method at an appropriate temperature and duration using ZIF-67 as a precursor, and melamine as an additional nitrogen source. The presence of melamine ensures adequate nitrogen content at high temperature, promotes the formation of NCNTs through the help of Co nanoparticles in the pyrolysis process and forms a mesoporous carbon structure. The optimum pyrolysis condition was found to be 800 °C for 4 h. A Pt-based catalyst was synthesized with the as-prepared Co@NCNTs-MC support which was found to significantly improve the dispersion of Pt nanoparticles and enhance the transportation of electrons and mass. Co-Nx bonds are shown to provide an abundance of active sites. A Pt/Co@NCNTs-MC800-4 sample is found to show mass activities of 700.3 mA mg−1Pt for methanol electrooxidation, which is approximately 4.5 times higher than that of 20% Pt/C. This work brings new opportunities to design and prepare promising catalyst supports for direct methanol fuel cells.