FeCoNi-based Alloy Coatings as Low Overpotential Electrocatalysts for Alkaline Water Electrolysis.

Developing efficient, stable and low-cost electrocatalysts is a viable approach to solve the current energy crisis. It is found that increasing the surface area of the electrodes can effectively promote the electrocatalytic efficiency. Herein, the atmospheric plasma spraying (APS) technology was used to prepare FeCoNi-Ni3C alloy coating by adding Ni3C powder to FeCoNi powder with an equal molar ratio. The atomic ratios of Ni3C in the powder are 25 %, 50 %, and 75 %, respectively. The results prove that the pores on the surface of the coating have increased after Ni3C doping, which can provide more active sites in the electrocatalytic process to promote the electrocatalytic reaction. By controlling the proportion of Ni3C, the porosity of the coating surface can be effectively regulated. In 1.0 M KOH electrolyte and 10 mA cm-2, the 50 at.% Ni3C coating shows an overpotential of 105 mV and 212 mV for HER and OER, respectively. It is worth noting that the 50 at.% Ni3C coating has a low Tafel slope of 45.78 mV dec-1 (HER) and 44 mV dec-1 (OER).  Furthermore, the 50 %at. Ni3C coating catalyst has a low potential of 1.664 V at 10 mA cm-2 in a water-splitting system.