Adsorption and decomposition mechanism of formaldehyde on Mn-doped Fe3O4 catalysts in the presence of water: Density functional theory and microdynamic approach

Density functional theory and micromechanical methods were used to investigate the adsorption and decomposition of formaldehyde on the surfaces of pure and Mn-doped Fe3O4 catalysts. The O-2 site was determined as the optimal adsorption site, and single doping with Mn promotes the generation of oxygen vacancies The ease of C-H bond breakage was as follows: single H2O> pure surface > double H2O: Fe3O4 (111) > MnFe 3 x-1O4x (111). The presence of OH facilitated the binding of O with H and promoted the cleavage of C-H bonds. The accumulation of water on the catalyst surface may result in the occupation of the top positions of Fe or O by dissociated OH and H, thereby impeding subsequent reactions. This study provides a promising direction for further investigation of the catalytic mechanism on the reaction between the Fe3O4 catalyst and HCHO, and ultimately provides guidance for the preparation and rational application of catalysts.