Facet-Controlled Pt₃M Alloys as Enhanced Catalysts for Ammonia Oxidation Reaction: A Combined Theoretical and Experimental Study

Ammonia (NH₃) is emerging as a promising carbon-free chemical energy source, offering higher storage capacity per unit volume compared to hydrogen and enhanced ease of liquefaction. This makes NH₃ suitable for long-distance transportation and various industrial applications. The ammonia oxidation reaction (AOR) is crucial for electrochemically converting NH₃ into H₂, but current AOR catalysts face commercialization challenges due to cost and efficiency issues. This study explores ways to enhance AOR catalysts through a combined theoretical and experimental approach, focusing on Pt₃X (where X represents screening elements) alloys. Density functional theory calculations were employed to analyze the AOR mechanism on Pt(111), (110), and (100) surfaces, identifying descriptors that facilitated the high-throughput screening of Pt₃X alloys with (111), (110), and (100) facets for the highest AOR activity. The selected Pt₃M (M = Fe, Co, and Ni) alloys were synthesized and characterized, revealing well-defined cubic shapes and superior AOR properties compared to pure Pt. Experimental results confirmed that Pt₃Fe and Pt₃Co nanocubes exhibit enhanced AOR activity and stability, aligning with theoretical predictions. This integrated approach highlights the potential of Pt₃M alloys as cost-effective and efficient AOR catalysts, advancing ammonia electrolysis technologies for hydrogen production.