Theoretical prediction of superatom WSi 12 -based catalysts for CO oxidation by N 2 O.

Catalytic conversion of N 2 O and CO into nonharmful gases is of great significance to reduce their adverse impact on the environment. The potential of the WSi 12 superatom to serve as a new cluster catalyst for CO oxidation by N 2 O is examined for the first time. It is found that WSi 12 prefers to adsorb the N 2 O molecule rather than the CO molecule, and the charge transfer from WSi 12 to N 2 O results in the full activation of N 2 O into a physically absorbed N 2 molecule and an activated oxygen atom that is attached to an edge of the hexagonal prism structure of WSi 12 . After the release of N 2 , the remaining oxygen atom can oxidize one CO molecule via overcoming a rate-limiting barrier of 28.19 kcal mol -1 . By replacing the central W atom with Cr and Mo, the resulting MSi 12 (M = Cr and Mo) superatoms exhibit catalytic performance for CO oxidation comparable to the parent WSi 12 . In particular, the catalytic ability of WSi 12 for CO oxidation is well maintained when it is extended into tube-like W n Si 6( n +1) ( n = 2, 4, and 6) clusters with energy barriers of 25.63-29.50 kcal mol -1 . Moreover, all these studied MSi 12 (M = Cr, Mo, and W) and W n Si 6( n +1) ( n = 2, 4, and 6) species have high structural stability and can absorb sunlight to drive the catalytic process. This study not only opens a new door for the atomically precise design of new silicon-based nanoscale catalysts for various chemical reactions but also provides useful atomic-scale insights into the size effect of such catalysts in heterogeneous catalysis.