Tailoring support defects in Ru/yttria-ceria catalysts for efficient and durable ammonia decomposition

Abstract

The catalytic decomposition of ammonia (NH3) offers a carbon-free route for on-demand hydrogen production; however, achieving high activity and durability under moderate temperatures remains challenging. Ru-based catalysts supported on CeO2 exhibit excellent intrinsic activity, but their performance is limited by insufficient defect density and moderate metal-support interaction. Here, we establish a structure-defect-interaction-performance relationship for Ru catalysts supported on yttria-ceria mixed oxides (Ru/aYCeOx) by systematically varying the Y content of the support. Incorporating Y3+ into the CeO2 lattice induces lattice distortion and oxygen vacancies while preserving the fluorite structure up to moderate Y contents. These structural defects strengthen the Ru-O-Ce interfacial bonding, facilitate electron transfer, and enhance the surface basicity of the support. The Ru/50Y-CeOx catalyst achieves 80 % NH3 conversion at 450 degrees C with a hydrogen formation rate of 10.8 mmol center dot gcat- 1 center dot min- 1 and maintains stable operation for 168 h without deactivation. This superior performance is attributed to the optimal defect density that maximizes Ru-support coupling, accelerates recombinative N2 desorption, and mitigates H2 poisoning. These findings highlight that tailoring lattice defects in rare-earth oxide supports provides a rational strategy for designing efficient and durable Rubased catalysts for carbon-free hydrogen production.