Strongly Coupled Ni-Molybdenum Carbide Grafted N-Doped Carbon Architectures for Efficient Electrocatalysis

Abstract

Despite the recent promise of transition metal carbides as non-precious catalysts for hydrogen evolution reaction (HER), their extension to oxygen evolution reaction (OER) in order to achieve the goal of overall water splitting remains a significant challenge. Herein, a new Ni/MoxC (MoC, Mo2C) nanoparticles supported N-doped graphene/CNT hybrid (NC) catalyst is developed via a facile, one-step integrated strategy which can catalyze both the HER and OER in an efficient and robust manner. The catalyst affords low overpotentials of 162 and 328 mV to achieve a current density of 10 mA/cm2 for HER and OER, respectively, in an alkaline medium which either compares favourably or exceeds most of the Mo-based catalysts documented in the literature. The electronic synergistic effect between MoxC, Ni and NC are responsible for the higher electrocatalytic activity wherein, a tandem electron transfer process yields both excellent HER and OER activity. [1] Unfortunately, however, the synergy among the components was curtailed on account of large spatial separation. To mitigate this problem, we pyrolyzed a PANI/NiMoO4 nanowire@rGO hybrid which brought the individual components closer as compared to the previously adopted method resulting in improved catalytic activity. To further enhance the intimacy in these multi-component catalysts, a MOF-confined synthesis method was developed which resulted in the best activity among all the catalysts developed in the series. Moreover, we further extended this strategy to other MOFs resulting in Co/Mo2C/NC architecture which points to the versatility of this method. [1] D.Das, S.Santra and K.K Nanda, ACS Appl. Mater. Interfaces, 2018, 10, 35025−35038