High Er doping in CeO2via lanthanide contraction boosts oxygen vacancy formation and ammonia decomposition

Abstract

Efficient and stable catalysts are vital for catalytic ammonia decomposition as a clean hydrogen source. In this study, CeO₂ support was modified via high Er doping to exploit the lanthanide contraction effect, enabling a wide range of substitution with Ce-to-Er ratios up to 1 : 0.67 without altering the fluorite structure. Among the prepared catalysts, Ni/CeEr_0.44O_x exhibited the highest activity, achieving nearly complete NH₃ conversion at 650 °C under a space velocity of 30 000 mL g_(cat)⁻¹ h⁻¹, together with excellent long-term stability. Comprehensive characterization revealed that substantial Er incorporation generated abundant oxygen vacancies, strengthened the metal–support interaction, and enhanced the electron density of Ni. These synergistic effects collectively facilitated N–N recombination and desorption, thereby enhancing both activity and durability. This work provides valuable insights into dopant-induced electronic modulation and oxygen vacancy engineering in promoting ammonia decomposition.