Co-embedded sulfur vacant MoS2 monolayer as a promising catalyst for formaldehyde oxidation: a theoretical evaluation

摘要

In this work, we theoretically evaluated the complete catalytic oxidation of formaldehyde (HCHO) catalyzed by a cobalt embedded sulfur vacant MoS2 (COSv-MoS2) monolayer. The density functional theory calculations demonstrate that the Co atom is strongly anchored at the S vacancy site of the MoS2 monolayer forming a single-atom catalyst without metal clustering. From the study of all possible elementary steps, we propose two possible catalytic pathways for HCHO oxidation; (1) consecutive path: HCHO dehydrogenation followed by CO oxidation with O-2, and (2) co-adsorption path: HCHO oxidation by O-2 through the Langmuir-Hinshelwood mechanism. Compared to the catalysts reported in the literature, this catalyst presents lower activation energy barriers for C-H bond cleavage. At room temperature, the consecutive path is found to be dominant, and the calculated activation free energy barrier is only 0.46 eV (44.38 kJ mol(-1)). Our kinetic analyses show that HCHO oxidation can easily occur at room temperature with a rate of 1.12 x 10(5) s(-1). Therefore, this non-noble metal single atom COSv-MoS2 catalyst demonstrates excellent activity for HCHO catalytic oxidation at low temperatures.