Theoretical Evidence of PtSn Alloy Efficiency for CO Oxidation

Abstract

The efficiency of PtSn alloy surfaces toward CO oxidation is demonstrated from first-principles theory. Oxidation kinetics based on atomistic density-functional theory calculations shows that the Pt3Sn surface alloy exhibits a promising catalytic activity for fuel cells. At room temperature, the corresponding rate outstrips the activity of Pt(111) by several orders of magnitude. According to the oxidation pathways, the activation barriers are actually lower on Pt3Sn(111) and Pt3Sn/Pt(111) surfaces than on Pt(111). A generalization of Hammer's model is proposed to elucidate the key role of tin on the lowering of the barriers. Among the energy contributions, a correlation is evidenced between the decrease of the barrier and the strengthening of the attractive interaction energy between CO and O moieties. The presence of tin modifies also the symmetry of the transition states which are composed of a CO adsorbate on a Pt near-top position and an atomic O adsorption on an asymmetric mixed PtSn bridge site. Along the reaction pathways, a CO2 chemisorbed surface intermediate is obtained on all the surfaces. These results are supported by a thorough vibrational analysis including the coupling with the surface phonons which reveals the existence of a stretching frequency between the metal substrate and the CO2 molecule.

The Mechanism of Low‐Temperature CO Oxidation on IB Group Metals and Metal Oxides

“…Therefore, the evolution of the activation barrier primarily follows the variation of the interaction energy DE int between the CO molecule and the oxygen atom. This is in good agreement with the results of Dupont et al, [50] who found that the variation of the activation energy primarily follows the variation of the interaction energy between CO and oxygen atom fragments.…”

“…A convenient way to interpret the stability of the TS has been introduced originally by Hammer for NO dissociation on metal surfaces [49] and later used by Dupont et al [50] to explain the CO oxidation process. The formula for adsorption energy at the TS is derived as follows [Eq.…”

Effects of heat treatment atmosphere on the structure and activity of Pt3Sn nanoparticle electrocatalysts: a characterisation case study

“…[4][5][6] The latter is key to more CO-tolerant catalysts for the anodes of reformate fuelled H 2 PEM fuel cells and direct alcohol fuel cells. Fundamental studies have shown that CO oxidation occurs at reduced overpotential at Sn and SnO 2 (or its hydrated form) modied Pt 7-10 and at Pt 3 Sn 11-14 compared to Pt electrodes.…”

CO-Tolerant PtMo/C Fuel Cell Catalyst for H2Oxidation

“…The role of Mo in CO electro-oxidation, however, remains elusive. Like in the case of PtSn and PtNi catalysts, 12,26,27 one cannot completely exclude a possibility that the modulation of electronic structure induced by Mo could have an effect on the interaction of Pt and CO, which also dictates the catalytic activity. To elucidate the alloying effect on the adsorption strength of CO, we investigated the role of Mo in CO electro-oxidation using X-ray absorption spectroscopy, and our results are discussed.…”