The Effect of Nickel Salt on OMS-2 Nanorods in Oxygen Reduction Reaction.

The practical applications of Pt-based nano-catalysts in oxygen reduction reaction (ORR) have been seriously restricted by their high cost and poor durability. Therefore, it is significantly desirable to explore high active, non-noble metal and low-cost electrocatalysts for ORR. Herein, a series of nickel salts [NiNH2SO3, Ni(NO3)2, NiSO4, NiAc2, NiCl2, and Ni(acac)2] doped MnO2 octahedral molecular sieves (Ni-OMS-2) nanomaterials are successfully synthesized by a simple hydrothermal reaction and used as cathodic ORR electrocatalyst. We also demonstrate that nickel salt has a significant influence on the porous structure, morphology and ORR performance. Notably, comparing with other nickel salts-doped Ni-OMS-2 catalysts, the resulting Ni-OMS-2 with NiNH2SO3 dopant exhibits impressive electrocatalytic performance toward ORR in alkaline (0.1 M KOH), with a more positive Eonset (0.866 V) and E1/2 (0.792 V), as well as high limited diffusion current (5.03 mA/cm2), respectively. Moreover, it displays superior long-term stability and methanol tolerance than that of commercial Pt/C, and the ORR process follows an ideal 4e− transfer pathway. Such outstanding ORR performance primarily contributes to the well-defined one-dimensional nanorods and nickel salts doping, which are in favor of promoting electron transfer, active sites exposure and intermediates absorption during the catalytic process. [ABSTRACT FROM AUTHOR]