Mechanism of formaldehyde advanced interaction and degradation on Fe3O4 (1 1 1) catalyst: Density functional theory study

Abstract

The mechanism of formaldehyde advanced interaction and oxidation on Fe3O4 (1 1 1) catalyst was investigated with and without the hydroxyl formation from H2O2 decomposition through density functional theory. Binding energies, Mulliken charge population, and the partial density of states were calculated on the basis of different adsorption sites for Fetet1 and Feoct2 terminal surfaces. It has been determined that formaldehyde showed weak interaction on Fetet1 terminal surface, and the carbon atom hardly formed a chemical bond both with and without H2O2. On Feoct2 terminal surface, the oxygen and carbon atoms of the formaldehyde were stably adsorbed on Fetet1/Feoct2 site, especially in the presence of H2O2. In formaldehyde oxidation, the formaldehyde was firstly oxidized into formic acid by hydroxylation and dehydrogenation. The energy barrier was 53.1 kJ/mol followed 103.4 kJ/mol, and 117.5 kJ/mol on Fetet1 and Feoct2 terminal surfaces, respectively. In formic acid oxidation, HCOOH preferred hydroxylation firstly and then produced H2O by dehydrogenation reaction on the two surfaces. The calculated binding energies suggested that the processes of formaldehyde oxidation and CO2 generation were generally exothermic on Fe3O4 (1 1 1) surface with H2O2.