Decoding ammonia decomposition: Screening and mechanistic insights into non-precious Ni-based alloy catalysts

Ammonia decomposition offers a promising pathway for carbon-free hydrogen production, yet developing efficient, cost-effective non-precious metal catalysts remains a significant challenge. In this study, density functional theory (DFT) was employed to systematically investigated the catalytic performance of 29 Ni-based alloys for ammonia decomposition. The results reveal that metal doping induces substantial modifications to the electronic structure of Ni alloys, directly influencing the binding strength of nitrogen intermediates. Early transition metal dopants exhibit strong N-binding, inhibiting N recombination, while post-transition and main group metal dopants (Cu, Zn, Ga, In, Sn) weaken N adsorption, effectively promoting the rate-determining N recombination step. A robust correlation between N adsorption energy (E_adsN) and reaction energy barriers was established, the optimal E_adsN range (−5.0 to −4.3 eV) was identified to balance dehydrogenation and N recombination, maximizing catalytic performance. This approach enables efficient catalyst screening, leading to the identification of NiZn and NiCu₃ as the most promising candidates with balanced dehydrogenation and N recombination performance. Machine learning shows that intrinsic properties of doped metals have a significant effect on N adsorption energy and ammonia decomposition activity. These findings provide a scalable computational strategy for catalyst screening, offering a clear pathway for the rational design of high-performance, cost-effective hydrogen production catalysts.