Engineering ultrafine and uniform La2O3 supports through a microwave-assisted DMF synthesis strategy for boosting CO oxidation.

Lanthanum oxide (La2O3) is a promising functional material owing to its excellent chemical stability, high dielectric constant, and catalytic properties. The particle size of La2O3 directly governs its catalytic activity, yet achieving precise control and uniform distribution of particle size remains a critical technical challenge in this field. To address this issue, this study systematically investigated the effects of various organic additives (SDBS, PEG-400, Tween-80, PVP K30, CTAB, and DMF) on the agglomeration behavior and particle size distribution of the material. Subsequently, the process was optimized to compare the influence of microwave heating and conventional water bath heating on the nucleation and growth kinetics of La2O3. The synthesized La2O3 materials were comprehensively characterized using LPS, FT-IR, TG/DSC, SEM, TEM, XRD, BET, and EDS. Results revealed that adding 1 wt% DMF and applying microwave heating for 30 min, followed by calcination, successfully yielded ultrafine La2O3 powders with a median particle size (D50) of approximately 1 μm and a highly uniform particle size distribution. The as-prepared La2O3 was then used as a support to fabricate Co-based catalysts (Co/La2O3) for CO catalytic oxidation. Activity tests confirmed that the Co/La2O3-5-MW-DMF catalyst, optimized through the microwave-DMF synergistic strategy, exhibited significantly enhanced catalytic activity. Mechanistic studies revealed that the support particle size governs Co dispersion, metal-support interactions, and oxygen vacancy concentration, key factors that collectively determine CO adsorption, activation, and catalytic performance. This work provides an effective strategy for the size-controlled synthesis of La2O3 and highlights the critical role of particle size regulation in optimizing catalytic performance.