Electrochemical deposition of nickel sulfide catalysts on commercial carbon rods as low-cost electrodes for hydrogen generation

Nowadays, the challenge of the world and the scientific community is to find and effectively use renewable energy sources. One of the renewable energy research subjects that has been hotly discussed recently is the water-splitting reaction to produce hydrogen. In this study, we focus on fabricating nickel sulfide (NiS) materials deposited on commercial carbon rod (CR) substrates and using them as electrodes for the electrochemical water-splitting reaction to produce hydrogen gas. In detail, NiS materials were decorated on commercial carbon rods (NiS/CR) by cyclic voltammetry electrochemical deposition with a potential range from 0.2 to -1.2 V (versus Ag/AgCl), a scan rate of 10 mV s-1, and 15 cycles. Benefiting a strong interfacial synergetic effect based on NiS/CR materials shows an excellent electrocatalytic activity for hydrogen evolution reaction (HER). Specifically, the NiS/CR electrode exhibits a high performance with low overpotential (70 mV for HER) and a slight Tafel slope (50 mV dec-1). Besides, annealing temperature helps increase the crystal properties, causing the appearance of NiS2 and Ni3S2 phases in NiS/CR@400 samples. Interestingly, the electrochemical surface area (ESCA) of the NiS/CR@400 sample significantly increased (17.3%) compared to the NiS/CR sample (5.8% of the total physical surface area) is due to the presence of NiS2 and Ni3S2, leading to NiS/CR@400 sample enhances the active sites by 16.0 mF cm-2. Furthermore, the long-term durability of NiS/CR@400 electrodes is good electrocatalytic over a continuous cycling 12-hour operation at 20 mA cm-2 in an alkaline environment. The NiS/CR is a promising electrode candidate for high HER performance, and here is a new design of electrocatalysts for water splitting.