Uncovering the role of Ag in layer-alternating Ni3S2/Ag/Ni3S2 as an electrocatalyst with enhanced OER performance

Abstract

It is increasingly important to develop an efficient OER catalyst that can provide high current density at low overpotentials to improve water splitting efficiency. Here, layered Ni₃S₂/Ag/Ni₃S₂(N2A1) nanosheets have been grown directly on carbon cloth via a facile alternating electrodeposition method. Compared to the electrocatalyst Ni₃S₂/Ag(N1A1) with Ag as the innermost layer, the Ag/Ni₃S₂(A1N1) catalyst with Ni₃S₂ nanosheets as the initial layer takes greater advantage of the low impedance for water splitting. Benefitting from the coexistence of different morphologies of Ni₃S₂, quasi-three-dimensional layered N2A1 exhibits excellent catalytic activity and stability toward OER, with an overpotential of 187 mV for 10 mA·cm⁻². Notably, based on the temperature-dependent measurement, the lower activation energy (E_a) of N2A1 is observed for the superior OER process. The roles of Ag in N2A1 were uncovered as affecting charge rearrangement, increasing electron transfer, and controlling morphology of Ni₃S₂.