Comparative study of Mn-ZIF-67 derived carbon (Mn-Co/C) and its rGO-based composites for the methanol oxidation

In this study, we report the comparative electrocatalytic study of commercial Pt/C with Mn-Co/C and its rGO based composites (i.e., 1–8 wt% rGO @Mn-Co/C) for methanol oxidation. Catalysts were synthesized by a two-step procedure. Firstly, via the solvothermal method, all catalysts were prepared and then pyrolyzed at 700 °C in an argon and hydrogen mixture environment. The characterization of the Mn-Co/C, 1–8 wt% rGO Mn-Co/C catalysts was accomplished by XRD, SEM, EDX, Raman, TEM, BET and XPS. The as-prepared dodecahedron morphology of the initial Mn-based ZIF-67 particles is retained, with the interconnected sheets of reduced graphene oxide after the pyrolysis in a reducing atmosphere (i.e., Ar+H 2 ). Among all the catalysts, the 5 wt% rGO@Mn-Co/C catalyst has shown much higher electrochemical activity (i.e., 235.24 mA/cm 2 ) and stability than other rGO-based Mn-Co/C catalysts and also than commercial Pt/C in 1 M NaOH and 3 M CH 3 OH. The presence of support materials such as rGO and the availability of nano porous carbon with Mn and Co may contribute to the improved electrocatalytic activity of 5 wt% rGO Mn-Co/C over Mn-Co/C. With a number of beneficial features in structure, composition, and nitrogen doping level, it results in enhanced electrocatalytic activity and stability as well as methanol tolerance when benchmarked with a commercial Pt/C electrocatalyst under the same testing conditions. • Mn-Co/C composites with rGO (1-8wt% rGO@Mn-Co/C) were synthesized solvothermaly at 120 °C and pyrolyzed at 700 °C. • Synthesized 1-8wt% rGO@Mn-Co/C composites were used as an electrocatalyst for MOR in alkaline media. • 5wt% rGO@Mn-Co/C composite exhibits higher catalytic activity with current density of 235.24 mA/cm 2 at 50mV/sec. • Catalytic activity of 5wt% rGO@Mn-Co/C composite is compared with commercial Pt/C. • Enhanced performance is due to synergic effect of rGO and residual metallic Co and Mn nanoparticles entrapped in rGO.