Synergistic Mn-Doping and Morphology Engineering of CeO ₂ for Enhanced CO ₂ Conversion with Monoethanolamine

The rational design of catalysts for the selective conversion of CO2 and monoethanolamine (MEA) into 1-(2-hydroxyethyl)-2-imidazolidinone (HEIA) remains a significant challenge. Herein, we present a synergistic strategy combining morphology engineering and electronic modulation to develop high-performance CeO2-based catalysts. Initial morphology control revealed that spindle-like CeO2 (F-CeO2), with its high surface area, abundant oxygen vacancies, and tip-enhanced local effects (meaning higher reactivity at sharp or tip-like regions), exhibits superior performance over spherical, octahedral, and cubic morphologies. Subsequent electronic modulation via Mn doping further enhanced the catalytic performance compared with undoped F-CeO2: the oxygen vacancy concentration increased by 38.6%, the distribution of surface basic sites shifted to be dominated by 81.20% weak basic sites, and the HEIA yield achieved an approximately 10% improvement. Mechanistic studies confirm that the abundant weak basic sites are crucial for selectively promoting the intermolecular dehydration pathway to HEIA, while suppressing competing reactions. This work provides a clear and effective blueprint for designing advanced CeO2 catalysts for selective CO2 utilization.