Strengthening the activity and CO tolerance with bi-component PtNi/ NbN-C catalyst for methanol alkaline electrooxidation

It is critical to create the anodic catalysts with high efficiency and economy for direct methanol fuel cells (DMFCs). Here, a series of PtNi/NbN-C catalysts (M=Co, Sn, Ni) are developed using the glycol solvothermal process, to investigate the catalytic effficiency for alkaline methanol oxidation reaction (MOR). Catalytic performance evaluation experiments show that the doped Ni species bring the enhancement effect on Pt/NbN-C for the alkaline MOR. The mass activities of PtxNiy/NbN-C show a volcanic trend with the increased Ni contents. PtNi/NbN-C has the highest mass activity (6025.5 mA<middle dot>mg(Pt)(-1)) for alkaline MOR, 18.3 times greater than that of the Pt/C commercial catalyst. The LSV, EIS, Tafel, CA and CO stripping results imply PtNi/NbN-C also exhibits the lowest onset potential, charge transfer resistance, fastest kinetics, highest CO tolerance and stability. When the XRD, HRTEM, and XPS analysis are combined, it is discovered that the electronic effect between the Pt, Ni, and NbN species is mostly responsible for the catalytic performance enhancement is mainly depend on the electronic effect among the Pt, Ni and NbN species. The presence of Pt in an electron-deficient state can enhance the conversion of adsorbed methanol and intermediates, evidenced by a direct relationship between the d-band centers and the mass activities for MOR of different catalysts. This study may provide guidance for the development of anodic materials for DMFCs.