Boosted Catalytic Performance of Ni2Co2@T-PMo@ZIF-67 for Glucose Oxidation in a Direct-Glucose Fuel Cell

In this study, we report on how to design efficient catalysts for glucose oxidation via the transitional metal doping of nanohybrids of polyoxometalates (POMs) and metal-organic frameworks (MOFs). ZIF-67, a cobalt-based MOF, as well as phosphomolybdic acid (PMo), were used as precursors for the fabrication of pyrolyzed PMo@ZIF-67 (T-PMo@ZIF-67). A different amount of Ni2+ was doped into PMo@ZIF-67 to produce NixCoy@T-PMo@ZIF-67. Among them, Ni2Co2@T-PMo@ZIF-67 had the best performance. The power density of the fuel cell that used Ni2Co2@T-PMo@ZIF-67 as an anode catalyst was 3.76 times that of the cell that used active carbon as an anode catalyst. SEM and EDS mapping results indicate that Ni2Co2@T-PMo@ZIF-67 has a spherical structure and rough surface, and elements such as cobalt, nickel, and molybdenum are evenly distributed. XRD characterization indicates that Co3O4, CoMoO4, CoNiO4, and MoNiO4 co-exist in the composites. It is supposed that Co2+, Mo6+, and Ni2+ in the composites may have synergistic effects on the catalytic oxidation of glucose.