Transition Metal-Based Ternary Catalysts Prepared By Electrodeposition for Hydrogen Evolution Reaction

Abstract

To solve the global warming problem caused by indiscriminate use of fossil fuel, hydrogen production technology via water electrolysis is drawing attention. It is known that the Pt catalyst has been reported to be excellent for hydrogen evolution reaction (HER), which inhibits commercialization of water electrolysis due to its high price. For this reason, non-noble metal-based catalysts have been investigated to achieve cost-effectiveness with acceptable catalytic performance. It has recently been studied focusing on transition metals (Ni, Co, Mo, etc.) combined with non-metals (B, N, O, S, P, etc.) and reported indicating improved HER performance of transition metal borides and transition metal phosphides. In this study, nickel based complex containing phosphides and borides catalysts (Ni-P-B) were prepared on the carbon paper substrate using electrodeposition method. Phosphorous is reported to act as an active site due to its abundance of electrons and high electronegativity, and thus the catalytic performance of transition metal phosphides to HER increased with an increase in P ratio. On the other hand, boron has a different aspect. In transition metal borides, boron was expected to act as an active site due to its abundance and high electronegativity, but in practice the boron's electrons increase catalyst activity by donating electrons to the empty d-orbital. Nickel-based compounds containing phosphorus and boron (Ni–P–B) may be catalysts for HER, given the advantages of nickel phosphides and borides, but little research has been done on this. An experiment was conducted to increase the performance of the transition metal by adjusting the ratio of P and B in combination with the different properties of the transition metal phosphides and borides. Deposition parameters such as deposition potential/time and bath configuration were changed to control their morphology and composition. Their catalytic activity for HER was tested in half-cell measurement with the acidic electrolyte. Then the activity orders based on geometric current, specific activity, and mass activity were connected with the results from analysis on material properties. Furthermore, employing the optimized catalyst in cathode, the performance of proton exchange membrane water electrolyzer was tested.