Electrocatalytic Activity of Pd−Co Bimetallic Mixtures for Formic Acid Oxidation Studied by Scanning Electrochemical Microscopy

doi:10.1021/ac901096h

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Title:	Electrocatalytic Activity of Pd−Co Bimetallic Mixtures for Formic Acid Oxidation Studied by Scanning Electrochemical Microscopy
Authors:	Jung, Changhoon;Sánchez-Sánchez, Carlos M.;Lin, Cheng-Lan;Rodríguez-López, Joaquín;Bard, Allen J.
Contributors:	淡江大學化學工程與材料工程學系
Date:	2009-07
Issue Date:	2013-05-31 11:39:55 (UTC+8)
Publisher:	Washington: American Chemical Society
Abstract:	The electrochemical oxidation of formic acid was studied by the tip generation-substrate collection (TG-SC) mode of scanning electrochemical microscopy (SECM), extending the number of applications of SECM in electrocatalysis. Formic acid was generated at a Hg on Au ultramicroelectrode (UME) tip by reduction of CO2 in a 0.1 M KHCO3 solution saturated with this gas. The electrocatalytic activity of different Pd−Co bimetallic compositions was evaluated using a Pd−Co electrocatalyst array formed by spots deposited onto glassy carbon (GC) as a SECM substrate. The SECM tip, which generated a constant formic acid flux, was scanned above the array and the oxidation current generated when formic acid was collected by active electrocatalytic spots was displayed as a function of tip position. This generated a SECM image that showed the electrocatalytic activity of each spot. SECM screening identified Pd50Co50 (Pd/Co = 50:50, atomic ratio) as a better electrocatalyst toward the formic acid oxidation than pure Pd or Pt in 0.1 M KHCO3 solution and this result was confirmed by cyclic voltammetry. Positive feedback was observed for the most active compositions of Pd−Co which suggests fast reaction kinetics and chemical reversibility during the oxidation of formic acid to CO2. Moreover this feedback increases the contrast between active and non-active spots in this imaging mode.
Relation:	Analytical Chemistry 81(16), pp.7003-7008
DOI:	10.1021/ac901096h
Appears in Collections:	[Graduate Institute & Department of Chemical and Materials Engineering] Journal Article

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