On the Catalytic Performance of (ZrO)_n (n=1-4) Clusters for CO Oxidation: A DFT Study

The unique characteristic of superatoms to show chemical properties like those of individual atoms opens a new avenue towards replacing noble metals as catalysts. Given the similar electronic structures of the ZrO superatom and the Pd atom, the CO oxidation mechanisms catalysed by (ZrO)_n (n=1-4) clusters were investigated in detail to evaluate their catalytic performance. Our results reveal that a single ZrO superatom exhibits superior catalytic ability in CO oxidation than both larger (ZrO)_n (n=2-4) clusters and a Pd atom, indicating the promising potential of ZrO as a "single-superatom catalyst". Moreover, the mechanism of CO oxidation catalysed by ZrO^+/- suggests that depositing a ZrO superatom onto the electron-rich substrates is a better choice for practical catalysis application. Accordingly, a graphene nanosheet (coronene) was chosen as a representative substrate for ZrO and Pd to assess their catalytic performances in CO oxidation. Acting as an "electron sponge", this carbon substrate can both donate and accept charges in different reaction steps, enabling the supported ZrO to achieve enhanced catalytic performance in this process with a low energy barrier of 19.63 kcal/mol. This paper presents a new realization on the catalytic performance of Pd-like superatom in CO oxidation, which could increase the interests in exploring noble metal-like superatoms as efficient catalysts for various reactions.