DFT Study of the CO Poisoning Effects on PdxCu1-x (110) Surface

CO contaminants play a significant role in modifying the performance of proton exchange membrane fuel cells (PEMFC). Pt is probably the most common catalyst being used today to absorb CO in the PEMFC, yet recent studies have shown that the use of Pd alloys such as Pd-Cu can increase the fuel cell efficiency versus a pure Pt catalyst. In this work, we examine the adsorption of CO onto PdxCu1-x (110) surfaces, with different values of x, in order to improve the CO tolerance. Understanding how molecules interact with such surfaces is the first step in understanding catalytic reactions. The study here presented was done using CASTEP, a computational code based on the plane-wave pseudopotential method of functional density theory. The surface structure of PdxCu1-x (110) was optimized and then the state density-functional, the repulsion energies and the chemisorption for CO on PdxCu1-x(110) were calculated. The results indicate that chemisorption energies of CO on PdxCu1-x are highly dependent on the concentration x of the alloy. In addition, density of states analysis indicate that the poisoning effect is partially due to the loss of Pd-Cu(d) electrons upon CO adsorption.