Nicup Catalyst with the Synergistic Effect of Ni and Cu for Hydrogen Production Using Ammonia Electrolysis

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Carbon neutrality using cleaner energy sources to replace fossil fuels is essential for climate change and a sustainable future. There are many candidates, including renewable energy, but hydrogen energy is gaining the most attention. Hydrogen energy is the most attractive alternative due to its abundance, renewability, and eco-friendliness as an energy source, however, its utilization is limited by transportation challenges. To solve this issue, various hydrogen carriers have been studied. Among them, ammonia is considered the closest to commercialization because it has an existing transportation infrastructure and does not contain carbon. In addition, ammonia can be electrochemically hydrogenated, and the theoretical reaction potential for this is 0.07 V vs. RHE, which is significantly lower than water electrolysis (1.23 V vs. RHE). Nevertheless, the actual reaction occurs at a potential between 1 and 2 V due to the high overpotential generated by the adsorption of NHx species on the surface during the reaction. Pt also has weaknesses like toxicity due to high nitrogen adsorption capacity, and its high price. To improve this, developing effective catalysts based on non-precious metal materials is important. In this study, a catalyst was synthesized using Ni, which has excellent nitrogen adsorption and ammonia oxidation reaction (AOR) properties, and Cu, which has desorption and dimerization properties of NHX species. Moreover, its phosphorylation improves catalyst durability and provides additional reaction sites. The as-prepared catalysts were characterized by physicochemical properties and electrochemical analysis along with the comparator, and the potential at 100 mA for AOR was 1.45 V vs. RHE. The catalysts were also evaluated for stability and hydrogen generation.