Size and Stoichiometry Effect of FePt Bimetal Nanoparticle Catalyst for CO Oxidation: A DFT Study

Optimizing chemical proportions is an urgent problem to be solved in the design of binary catalysts. In the present paper, a kinetics process is simulated to explain the size effect and chemical proportion dependence of catalytic activity on FePt bimetallic nanocatalysts. By DFT calculation, we obtained the optimal ratio and size of the FePt catalyst to achieve maximum catalytic activity. As a result, the optimum chemical ratio (Fe/Pt = 2.1/1) has the highest catalytic activity compared to that of other ratios and the microreaction mechanism of CO oxidation can be controlled by adjusting the Fe/Pt atomic ratio to form different special structure nanoparticles. The reaction determining step (RDS) of Pt₅₅ and Fe₄₃Pt₁₂ nanoparticles is that of CO assisting O₂ dissociation, but the reaction determining step of direct O₂ dissociation is occurred at Fe₁₃@Pt₄₂ core–shell structure nanoparticle. To compare with Pt₅₅, a 0.16 eV lower energy barrier of RDS is at Fe₄₃Pt₁₂ nanoparticle (with the specific structure of a single Pt atomic site), which suggests that this monatomic catalyst can markedly enhance the catalytic activity of CO oxidation.