Disordered but Efficient: Understanding the Role of Structure and Composition of the Co–Pt Alloy on the Electrocatalytic Methanol Oxidation Reaction

Abstract

A systematic investigation of the electrocatalytic Methanol Oxidation Reaction (MOR) was carried out using a model Co:Pt alloy system with different compositions and structural arrangements of the Co and Pt atoms. The structural variations with the same alloy composition included those with disordered arrangement of Co and Pt atoms in a face-centered cubic (fcc) lattice and ordered arrangements in face-centered tetragonal (fct) lattices. Our investigations clearly show that structures with disordered arrangements with Co:Pt atomic ratios near to 1:1 display better electrocatalytic efficiencies even when compared to pure Pt. These experimental findings were then rationalized by means of Density Functional Theory (DFT) calculations. Electronic level signatures in terms of charge transfer and relative shift in the peaks of the d band for surface metal atoms are proposed to be the reasons for the superior catalytic activity of a particular composition over the others. An increase in the number of inequivalent sites for methanol adsorption in disordered systems appears to result in better catalytic performance in comparison with ordered systems.

Alloying with Mn Enhances the Activity and Durability of the CoPt Catalyst toward the Methanol Oxidation Reaction

“…Previously, we have reported a DFT study for PtCo binary alloy catalysts with different compositions and tested them as catalysts for MOR . In this study, it was concluded that an increase in electron density on Pt significantly improves the electrochemical performance of Pt-based catalysts. ,, The current results also endorse this postulation.…”

“…The incorporation of extra transition metals like Mn and Co into Pt in a Pt 100– x (MnCo) x /C (16 < x < 41) catalyst is expected to modify the electronic structure of the Pt surface, promote reaction kinetics, facilitate electron transfer, and also accelerate the removal of CO molecules to improve MOR catalytic activity, as has been confirmed in numerous reports. − , These findings, as summarized in Figure , help to explain why the trimetallic Pt 100– x (MnCo) x /C (16 < x < 41) catalyst is active as compared to Pt/C. Previously, we have reported a DFT study for PtCo binary alloy catalysts with different compositions and tested them as catalysts for MOR . In this study, it was concluded that an increase in electron density on Pt significantly improves the electrochemical performance of Pt-based catalysts. ,, The current results also endorse this postulation.…”

“…Alloys of Pt with other transition metals such as Ru, Co, Ni, and Fe are known to enhance the activity and durability of the electrocatalyst . Thus, Pt-based alloys such as PtRu, PtNi, PtAu, PtPd, and PtCo have attracted widespread attention in recent years. Among the various Pt-based alloys, PtCo bimetallic alloys have been the most promising catalysts for MOR. , Despite great progress made in the development of bimetallic alloys as MOR catalysts, a material that displays better activity and durability than commercial Pt-based catalysts is still elusive.…”

Fabrication of donor‐acceptor ‐donor type conjugated polymers@double‐layered hollow carbon spheres composite as PtCu alloy catalyst support for MOR

“…The increasing global energy and environmental crisis promote the development of clean and renewable energy technology. As a green portable power source, direct methanol fuel cells (DMFCs) are the proper alternatives to traditional fossil fuels because of their higher energy density, stable conversion efficiency and low pollutant emission 1,2 . Currently, Pt‐based materials are widely used as an anode catalyst in DMFCs, but the low abundance, high cost and easily poisoning of Pt catalyst by CO‐like intermediates (COads), and poor durability of operation have been decreased the catalytic reaction efficiency significantly limited its commercialization worldwide 3 .…”

“…As a green portable power source, direct methanol fuel cells (DMFCs) are the proper alternatives to traditional fossil fuels because of their higher energy density, stable conversion efficiency and low pollutant emission. 1,2 Currently, Pt-based materials are widely used as an anode catalyst in DMFCs, but the low abundance, high cost and easily poisoning of Pt catalyst by CO-like intermediates (COads), and poor durability of operation have been decreased the catalytic reaction efficiency significantly limited its commercialization worldwide. 3 And these disadvantages have triggered the research for promising catalyst support that can enable the Pt to distribute uniformly with low consumption and greatly enhance the electrocatalytic activity.…”