The Role of Cu in Degrading Adsorption of CO on the Pt_nCu Clusters

Abstract

The platinum copper alloy nanocrystals (NCs) have generated much interest because of their wide applications in fuel cells due primarily to their good catalytic performance and to decreasing sensitivity toward CO poisoning. The exact atomic-level morphology of platinum copper alloy NCs is still not clear in the literature, and research to understanding the poisoning mechanism is still insufficient to date. In this article, we report on density functional calculations of small PtnCu clusters and their adsorption of a CO molecule that provide evidence for degrading adsorption of the CO molecule compared to pure platinum clusters. The lowest-energy geometries of PtnCu and PtnCuCO clusters have been identified. The CO molecule prefers to be adsorbed on the nearest platinum atom by the C-end-on mode, forming linear or quasi-linear O-C-Pt structures. The adsorption energies indicate that the introduction of a copper atom decreases the adsorption ability of the CO molecule. The local density of states of the representative clusters is used to characterize the adsorption properties of the CO molecule on the PtnCu clusters. Results from our theoretical calculations can be helpful for understanding the poisoning mechanism of the CO molecule on the platinum copper alloy NCs.

Stability of Ni Clusters and the Adsorption of CH4: First-Principles Calculations

“…From this observation, we expect smaller electrostatic interactions of the HOMO orbitals, degrading the adsorption of CH 3 . 44 On the other hand Ni 12 possesses more localization on the cluster surface. We also attribute this property to the low coordination of Ni 10 (ECN = 4.71) in comparison to Ni 12 (ECN = 5.47).…”

Tolerance of platinum clusters to CO poisoning induced by molybdenum doping

“…[24][25][26][27][28] Recently, the importance of electronic structure effects for CO tolerance enhancement was theoretically characterized for small Pt n Cu (n ≤ 7) clusters and for alloy Pt-Ti clusters up to sizes of 201 atoms. 29,30 The effect of composition on the electronic structure in small clusters and the consequences for the CO adsorption energy have been illustrated for 13-atom Pt-Au clusters and demonstrated the importance of the local environment of the transition metal atom with the CO adsorbed. 31 The enhancement of the CO tolerance in comparison with bulk alloys was demonstrated for a number of Pt-Me (Me = Mo, Nb, Ru, Sn, and Ag) clusters and nanocrystals.…”

Synthesis and Characterization of Platinum and Platinum based Alloy Nanoparticles Anchored on Various Carbon Materials for Methanol Oxidation in a DMFC – A Short Review

“…HRTEM image (Fig. 5f) of PtCo/rGO catalyst with a Pt:Co ratio of 1:9 shows the 'd' spacing's of 2.23 and 2.19 Aº corresponding to (111) and ( 220) planes of PtCo. The decrease in 'd'values of PtCo alloy in comparison to that of pure Pt ( 111) is explained by the substtution of cobalt for Pt thus confirming the formation of PtCo alloy and that these results are in consistent with the XRD results.…”

“…It has recently been found that Cu also exhibit water activation and other related reaction, such as the electro-reduction of CO2 [110]. Therefore, the alloy of Pt with Cu are considered to be effective electrocatalysts catalysts which are resistant to COads and similar intermediates [111]. Therefore, PtCu alloy catalysts supported on different support materials including multiwalled carbon nanotubes, carbon black and rGO etc have recently attracted a great attention for MOR both in acidic as well as in alkaline medium [96,99,110,[112][113][114][115][116][117] etc.…”

“…18(b) shows the X-ray diffraction patterns of commercially available Pt/C, Pt with N doped rGO and PtCu alloy nanoparticles supported on N-rGO respectively. In Pt/N-rGO catalyst, the XRD peaks appearing at 2θ are 39.78, 46.36, 67.55 and 81.33° correspond to (111), ( 200), ( 220) and (311) planes, of fcc structure of Pt. However, in case of PtCu (1:2)/N-rGO catalyst, it is seen that all the diffraction peaks due to Pt shift to higher 2θ angles [40.42, 47.43, 68.52 and 82.84°] for ( 111), ( 200), ( 220) and (311) respectively) indicating a lattice contraction as a result of incorporation of small Cu into the Pt sites.…”