Enhancing ammonia decomposition in a LaCeOx/Ni inverse catalyst by tuning lattice strain and oxygen vacancies

Abstract

This study successfully prepared a novel LaCeO_x/Ni catalyst with an inverse structure using a stepwise precipitation method. The catalyst was systematically compared with single-oxide supported catalysts (CeO₂/Ni and La₂O₃/Ni) and Bulk Ni to investigate the relationship between its catalytic performance and structural characteristics. The optimized LaCeO_x/Ni catalyst exhibits excellent catalytic performance, achieving an ammonia conversion of 70% and a hydrogen production rate of 93 mmol (g_cat min)⁻¹ at 550 °C and a gas hourly space velocity of 120 000 mL (g_cat h)⁻¹, with an activation energy (E_a) of 65.9 kJ mol⁻¹, outperforming most existing catalysts. The excellent activity remained stable for 150 h at 550 °C. It was found that La was doped into the CeO₂ lattice, forming a Ce–O–La solid solution that induces lattice strain and promotes the generation of oxygen vacancies. This regulation of lattice strain and oxygen vacancies enhanced metal–support interactions, generating electron-rich interfacial Ni sites. This work elucidates the profound impact of lattice strain and oxygen vacancy tuning on catalytic performance, laying an important foundation for the rational design of high-performance inverse-structured catalysts.