(49b) A Computational Evaluation of Steady-State Bifunctional Catalysis

Significant improvements in computer hardware, increasingly efficient and accurate density functional theory (DFT) codes, and the use of scaling and Brønsted-Evans-Polanyi relations in heterogeneous catalysis, have enabled us to predict optimal materials for various catalytic processes computationally. However, as the best catalysts are not always practical due to their high cost, it is essential to continue the discovery new and affordable materials with high catalytic activity. In the literature, several examples of high performance catalysts with multiple site-specific functionalities at steady-state have been reported [1-4]. The most common systems consist of two distinct sites that catalyze different reaction steps independently and are often referred to as “bifunctional catalysts”. Using DFT and microkinetic modeling, we aim to understand the mechanisms that are responsible for bifunctional activity and provide a computational framework for screening of bifunctional catalysts. Our results indicate that there are theoretical limits for the achievable activity improvement and bifunctional catalysts do not necessarily outperform single-site catalysts. More specifically, for CO oxidation on bimetallic systems we found that the overall activity is not significantly altered when bifunctional catalysts are considered, but equally active bifunctional catalysts may be tailored from less active and cheaper components.

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