Beyond Conventional Catalyst Design: A Perspective on the Inverse Catalyst Strategy in Ammonia Synthesis and Decomposition

The development of heterogeneous catalysts for industrial reactions, such as ammonia synthesis and decomposition, is approaching the limits set by conventional design strategies that primarily aim to improve metal dispersion. In kinetically constrained reactions, however, catalytic performance is more strongly influenced by the structure and electronic properties at the interface between the metal and the support, or the metal and the promoter; thus, simply increasing metal dispersion does not necessarily lead to improved catalytic activity. This has spurred growing interest in inverse catalyst architectures, in which the traditional metal-on-support configuration is structurally inverted, and the metallic surface is loaded with promoters. Such architectures enable control of active-site structure, allowing high densities of efficient active sites even at lower specific surface areas. Importantly, inverse systems are especially attractive for catalysts based on earth-abundant metals, as they maximize metal utilization while requiring only a small amount of promoter species. In this perspective, we highlight and discuss the structural and electronic aspects of inverse catalyst design and outline interface engineering as a direction for next-generation catalysts.