Single Al atom anchored on defective MoS2: An efficient catalytic site for reduction of greenhouse N2O gas by CO or C2H4 molecules

Abstract

Single-atom catalysts have gained a lot of interest recently due to their remarkable catalytic activity in a number of chemical processes. Using density functional theory calculations, we investigate an Al-atom doped MoS2 (Al-MoS2) as a potential catalyst for the reduction of nitrous oxide (N2O) by CO or C2H4 molecules. The reduction of N2O over Al-MoS2 is achieved in two steps. N2O is first decomposed on the Al atom to form the Al-O* active site, and then CO or C2H4 interacts with the Al-O* site to generate CO2 or ethylene oxide. The elimination of the O* by a CO molecule on the Al atom requires a negligible activation barrier (0.05 eV), which is lower than previously obtained for noble metals. The adsorbed O* species on Al-MoS2 need a barrier of 0.36 eV to oxidize ethylene, which seems to be overcome at low temperatures. Since the adsorption energy of an O2 molecule is smaller than that of a N2O, N2O is expected to dominantly occupy the active site of Al-MoS2 catalyst. Nonetheless, it is found that the introduction of an O2 molecule increases the activation energies required for the removal of O* by CO and C2H4, and therefore prologs the reaction times.