Modeling of bimetallic Pt-based electrocatalyst on extended-surface support for advanced hydrogen compression and separation

Abstract

Electrochemical hydrogen compression (EHC) process can be used to purify and separate hydrogen from its mixtures. In this regards question of carbon monoxide (CO) tolerance of electrocatalyst, used in such a process (e.g., Pt), becomes extremely relevant. One of the approaches to increase CO tolerance is to add ruthenium metal to platinum electrocatalyst. Results of density functional theory modeling of CO adsorption on Pt-Ru alloy slabs and edges are presented in this paper. It was found that Pt2Ru alloy has higher CO adsorption energy difference on Ru and Pt atoms, ECO(Ru)-ECO(Pt), than that of PtRu2. Effect of contraction and stretching of support on CO adsorption was also investigated: stretching increases CO adsorption energy, while contraction has opposite effect. We also found that 110 surface and edges of electrocatalyst have higher CO adsorption energy than 111 surface. Finally, we considered an elementary nano-object of the modeled extended surface, whiskerette. Using molecular dynamics with Sutton-Chen potential, we simulated annealing of platinum whiskerette at 800 K and calculated trend of CO coverage: number of CO active sites increases with temperature, and after cooling, it does not reach the initial level