Abstract
The interfacial sites of supported metal catalysts are often critical in determining their performance. Single-atom catalysts (SACs), with every atom contacted to the support, can maximize the number of interfacial sites. However, it is still an open question whether the single-atom sites possess similar catalytic properties to those of the interfacial sites of nanocatalysts. Herein, we report an active-site dependent catalytic performance on supported gold single atoms and nanoparticles (NPs), where CO oxidation on the single-atom sites is dramatically promoted by the presence of H2O whereas on NPs’ interfacial sites the promoting effect is much weaker. The remarkable H2O promoting effect makes the Au SAC two orders of magnitude more active than the commercial three-way catalyst. Theoretical studies reveal that the dramatic promoting effect of water on SACs originates from their unique local atomic structure and electronic properties that facilitate an efficient reaction channel of CO + OH.
Highlights
The interfacial sites of supported metal catalysts are often critical in determining their performance
Many experimental results have demonstrated that on reducible oxides supported metal catalysts, CO oxidation often occurs at the interfacial perimeter sites[1,2,14,15], and the activity can be enhanced by the presence of interfacial OH-groups[6,16] which are continuously supplied by the presence of water (H2O) in the reactant gas mixture[6,17,18,19]
A very low Au loading of 0.03 wt% was used to ensure all Au atoms are isolated and remain as SACs21. This loading is comparable to the level of commercial three-way catalysts (TWCs)[23], being convenient to perform catalytic test comparison with those of TWCs
Summary
The interfacial sites of supported metal catalysts are often critical in determining their performance. Computational modeling based on density functional theory (DFT) reveals that the significant difference in the water promoting effect originates from the different active-site structure and electronic properties between Au single atoms in the Au SAC and the interfacial Au atoms in supported Au NP catalysts.
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