Understanding the Impact of Hydroxyls on Synthesizing the Bimetallic Alloy Pt3Co on Al2O3 for CO-PROX
The anchoring effect between surface hydroxyls (–OH) and metal species has been extensively utilized to enhance catalyst stability. Nevertheless, few studies have investigated the impact of alloying process involving different types of –OH species. In this research, we discovered that the formation of the alloy particles Pt 3 Co was significantly influenced by the presence of distinct –OH species on Al 2 O 3 . Intriguingly, those Pt 3 Co alloy particles exclusively formed on α-Al 2 O 3 owing to the weak interaction between both Pt and Co species and the triply bridging hydroxyls (µ 3 -OH). In contrast, Pt and Co species were found to be separately dispersed on γ-Al 2 O 3 because of the strong anchoring effect of terminal hydroxyls (µ 1 -OH), especially for Co atoms. Density functional theory (DFT) calculations highlighted the difference in adsorption energies of the two metals on different hydroxyl groups, providing a theoretical rationale for the influence of hydroxyl groups on alloy formation. The presence of Pt 3 Co alloy resulted in a fourfold increase in the specific catalytic rate of Pt 3 Co/α-Al 2 O 3 in CO-PROX compared to Pt 3 Co/γ-Al 2 O 3 . Arguably for the first time, this study demonstrates the association between alloy formation and –OH groups, providing a unique perspective on the design of alloy catalysts.
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