Methanol Oxidation on Pt₃Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition

Abstract

PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.

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

“…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. Similarly, Sn modied Pt surfaces and Pt 3 Sn catalysts have also shown enhanced activity over Pt for methanol, [15][16][17] ethanol 18-21 and butanol 22 oxidation. In each case the nature of the Sn species, SnO 2 or metallic Sn, and the extent of mixing of the Pt and Sn, alloy formation and the resulting Pt : Sn ratio at the surface, may play a role in determining the activities of the electrocatalysts.…”

A dimer path for CO dissociation on PtSn

“…[1][2][3] Amongst them, PtSn nanoalloys have been applied as CO oxidation catalysts [4][5][6][7] and anodes in hydrogen and direct alcohol fuels cells. [8][9][10][11][12][13] The mixing pattern of bimetallic alloy particles differs typically from the corresponding bulk and is generally complex depending both on the constituent metals and the synthesis method. [14][15][16] Exposure of reactants to alloy nanoparticles adds complexity.…”

超细PtCu纳米线的表面结构调控及其增强的醇类 电催化氧化作用

“…The former two surfaces were mainly observed on the smooth NWs and the latter two on the rugged NWs. As reported in previous studies [64,65] It is noted that steps (i)-(v) and (vii) are the proton coupled electron transfer (PCET) steps, and step (vi) is a thermodynamic step. In our calculations, we assume that for PCET step the electrochemical driving force (i.e., the applied potential) is needed if its free energy change is…”