Exploring the effects of potassium-doping on the reactive oxygen species of CeO2 (110) for formaldehyde catalytic oxidation: A DFT study

The influence of K-doping on the reactive oxygen species and elementary reactions of HCHO catalytic oxidation has not been well understood. Herein, a density functional theory (DFT) study was conducted and found that the introduction of K-doping advantageously changed the electronic structures of both Ce and O atoms on the (110) crystal plane of CeO2. This change, in turn, facilitated the adsorption and activation of HCHO and O2 molecules, enhanced the mobility of lattice oxygen, and reduced the energy barrier associated with HCHO oxidation. The adsorbed oxygen species were generated through the direct dissociation of O2 on the CeO2 (110) surface. However, in the case of K-CeO2 (110), it was more probable for the adsorbed oxygen species to be produced by gaseous O2 filling the oxygen vacancy, followed by dissociation. Additionally, the incorporation of K-doping proved to be advantageous in facilitating the formation of hydroxyl groups by promoting the dissociation of water molecules. The inclusion of hydroxyl groups facilitated the HCHO adsorption and reduced the energy barrier for its subsequent oxidation. The findings provide new insights into the development of novel catalysts for HCHO removal with high performance through alkali metal modification.