Morphology-driven oxygen vacancy engineering in Co3O4 nanostructures for enhanced catalytic conversion of CO2 to 2-imidazolidinone

Abstract

Morphology-engineered Co₃O₄ nanomaterials (rods, cubes, sheets, and particles) with well-defined crystal facets were synthesized as model catalysts to probe the structure–activity correlation in the direct synthesis of 2-imidazolidone from CO₂. The distribution of surface Co³⁺ and oxygen species was demonstrated to be morphology-dependent, with Co₃O₄ nanorods (Co-R) outperforming nanocubes (Co-C), nanosheets (Co-S), and nanoparticles (Co-P) in catalytic activity. The enhanced performance of Co-R stemmed from its abundant surface oxygen vacancies and Co³⁺ sites, synergistically promoting CO₂ adsorption and activation, with further activation of reaction intermediate and reduction of overall energy barriers. More impressively, the Co-R catalyst also showed excellent stability during four cycles of use. Mechanistic studies elucidated the active-site configuration and reaction pathway for 2-imidazolidone formation, highlighting the critical role of surface defects and Co³⁺-O coordination in driving the catalytic cycle. This work offers a promising way to develop high-efficiency Co-based oxide catalysts with high 2-imidazolidone selectivity and stability through controlling oxygen vacancies by morphology-dependent synthesis.