Morphologically tailored nano-structured MoS2 catalysts via introduction of Ni and Co ions for enhanced HER activity

Recently Ni2+ and Co2+ incorporated MoS2 nanocatalysts demonstrated the superior HER performance compare to the pristine MoS2 nanostructures. Further investigation on the comparative HER behavior of these materials is required as there are only a few reports have been published so far. Here in, the HER performance of the Ni2+ and Co2+ incorporated MoS2 nanocatalysts (referred to as Ni-MoS2, Co-MoS2) compared with pristine MoS2 directly grown on carbon cloth via hydrothermal method. The SEM images revealed the distinguished morphology of Ni-MoS2, Co-MoS2 compare to pristine MoS2. The XPS and Raman studies confirmed the incorporation of transition metal ions in 2H phase of MoS2 lattice. Moreover, the transition metal ion incorporated MoS2 nanocatalyts showed a significant drop in overpotential (η10 @ j = 10 mA/cm2). The measured η10 was found lowest for Co-MoS2 (−58 mV) compare to Ni-MoS2 (−136 mV) and pristine MoS2 (−167 mV). The promoted HER activity in Co-MoS2, Ni-MoS2 analyzed by Tafel slope analysis and electrochemical impedance spectroscopy (EIS). The EIS measurements showed a significant increase in the active site density and lowering of the charge-transfer resistance (Rct), resulting in lower overpotential.