A novel Ni-S-Mn electrode with hierarchical morphology fabricated by gradient electrodeposition for hydrogen evolution reaction

A novel Ni-S-Mn electrode with hierarchical porous morphology of multi-channel wind-erosion-gully was fabricated through gradient electrodeposition. XRD and XPS were adopted to investigate chemical composition and elemental valence states; SEM, TEM and EDS were employed to characterize morphology and microstructure; LSV, CV and EIS were used to study electrocatalytic properties and stability of Ni-S-Mn electrode. The characterization of microstructure combined with the evaluation of electrocatalytic performances proved that the Ni-S-Mn electrode surface composition are of hierarchical porous morphologies, including the crystalline Ni₃S₂ and MnS flake structure as framework and the amorphous Ni as intergranular fillings; electron transfer efficiency can be effectively accelerated by crystalline sulfide; the layered structure of electrode surface facilitates the mass transfer of hydrogen molecules and electrolyte solution during hydrogen evolution reaction (HER). Particularly, the as-fabricated Ni-S-Mn electrode has a remarkable electrochemical surface area (ECSA) of 43180 cm², that is extremely higher among all other Ni-based electrode fabricated by electrodeposition. In addition to its excellent electrochemical stability confirmed by chronoamperometry (CA) at -100 mV vs. RHE for 15 h, the current density of Ni-S-Mn deposits on this novel electrode can reach as high as 713.8 mA cm^-2 at an overpotential of 0.4 V vs. RHE.