NO reduction over an Al-embedded MoS2 monolayer: a first-principles study

Abstract

Converting toxic air pollutants such as nitric oxide (NO) and carbon monoxide (CO) into less harmful gases remains a critical challenge for many industrial technologies. Here, by performing first-principles calculations, we introduce a cheap, stable and novel catalyst for the conversion of NO and CO molecules into N₂O and CO₂ using Al-doped MoS₂ (Al–MoS₂). According to our results, dissociation of NO molecules on Al–MoS₂ has a large energy barrier (3.62 eV), suggesting that it is impossible at ambient temperature. In contrast, the coadsorption of NO molecules to form (NO)₂ moieties is characterized as the first step of the NO reduction process. The formed (NO)₂ is unstable on Al–MoS₂, and hence it is easily decomposed into N₂O molecules, and an oxygen atom is adsorbed onto the Al atom (O_ads). This reaction step is exothermic and needs an activation energy of 0.37 eV to be overcome. Next, the O_ads moiety is removed from the Al atom by a CO molecule, and thereby the Al–MoS₂ catalyst is recovered for the next round of reaction. The side reaction producing NO₂ via the reaction of NO with the O_ads moiety cannot proceed on Al–MoS₂ due to its large activation energy.