Controllable synthesis of nickel sulfides integrated with carbon fibers towards enhanced hydrogen evolution reaction kinetic

Abstract

Nickel sulfides are considered as one of the promising electrocatalysts for hydrogen evolution reaction (HER). Herein, the monolith NiSx@CNFs as HER working electrodes were constructed via in situ electrospun and its crystal phase of Ni9S8 and NiS could be controlled by adjusting annealing temperature and S source. Specially, the NiS-800@CNFs exhibits the excellent activity with the required overpotential of 119 mV at 10 mA cm-2. This is attribute to the sulfur-deficient Ni9S8 crystal that provides sufficient hydrogen adsorption sites, with the coexistence of NiO phase that is beneficial for water dissociation, which synergically promotes the alkaline HER process. Based on electrochemical impudence-spectroscopy (EIS) characterization, the HER mechanisms of NiSx@CNFs series were systematically explored. It is revealed that the surface of sulfur-rich NiS crystal is not conducive to the desorption of adsorbed hydrogen to produce hydrogen. This work provides a valuable reference for the phase structure regulation and the HER influence mechanism of nickel sulfides.