The effect of specific chloride adsorption on the electrochemical behavior of ultrathin Pd films deposited on Pt(1 1 1) in acid solution

The electrochem. behavior of thin Pd films supported on a Pt(111) electrode is investigated by cyclic voltammetry and in situ Fourier transform IR (FTIR) spectroscopy. It is demonstrated that in perchloric acid soln. underpotential deposition of hydrogen (Hupd) and hydroxyl adsorption (OHad) is in strong competition with the adsorption of Cl- anions, the latter being present as a trace impurity in HClO4. The interaction of Cl- with Pd is rather strong, controlling the adsorption of Hupd and OHad as well as the kinetic rate of CO oxidn. The microscopic insight (the binding sites) of the adsorbed CO (COad) and the rate of CO oxidn. (established from CO2 prodn.) on Pt(111) modified with a (sub)monolayer of Pd is elucidated by means of Fourier IR (FTIR) spectroscopy. The appearance of both the characteristic Pt(1 1 1)-COad and Pt(1 1 1)-1 ML Pd-COad stretching bands on a Pt(1 1 1) surface covered by 0.5 ML Pd confirms previous findings that the Pd atoms agglomerate into islands and that the bare Pt areas and the Pd islands behave according to their own surface chem. The systematic increase of the Pd surface coverage results in a gradual change in the catalytic properties of Pt(111)-xPd electrodes towards CO oxidn., from those characteristic of bare Pt(111) to those which are characteristic for Pt(111) covered with 1 ML of Pd. [on SciFinder(R)]     «

The electrochem. behavior of thin Pd films supported on a Pt(111) electrode is investigated by cyclic voltammetry and in situ Fourier transform IR (FTIR) spectroscopy. It is demonstrated that in perchloric acid soln. underpotential deposition of hydrogen (Hupd) and hydroxyl adsorption (OHad) is in strong competition with the adsorption of Cl- anions, the latter being present as a trace impurity in HClO4. The interaction of Cl- with Pd is rather strong, controlling the adsorption of Hupd and OHad...     »

Chemically modified electrodes (carbon monoxide electrooxidn. on ultrathin Pd films deposited on Pt(111) in acid soln.) Adsorption (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(1 1 1) in acid soln.) Electrodeposits Ultrathin films (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.) IR spectra (of CO adsorbed on Pt(111) with and without ultrathin Pd film in HClO4 soln.) Oxidation (of CO adsorbed on Pt(111) with ultrathin Pd film in HClO4 soln.) Cyclic voltammetry (of Pt(111) electrtode with ultrathin palladium film in HClO4 soln.contg. trace of HCl) Underpotential deposition (of ultrathin Pd films on Pt(111) in acid soln. contg. PdO) palladium ultrathin film deposited platinum carbon monoxide electrooxidn     «

Chemically modified electrodes (carbon monoxide electrooxidn. on ultrathin Pd films deposited on Pt(111) in acid soln.) Adsorption (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(1 1 1) in acid soln.) Electrodeposits Ultrathin films (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.) IR spectra (of CO adsorbed on Pt(111) with and without ultrathin Pd film in HClO4 soln.)...     »

CAN 138:294032 72-8 Electrochemistry Institut fuer Physikalische und Theoretische Chemie, Universitat Bonn, Bonn, Germany. Journal 0039-6028 7440-05-3P (Palladium) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PNU (Preparation, unclassified), PREP (Preparation), PROC (Process) (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.); 16887-00-6 (Chloride) Role: NUU (Other use, unclassified), USES (Uses) (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.); 7601-90-3 (Perchloric acid) Role: NUU (Other use, unclassified), USES (Uses) (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in soln. contg.); 630-08-0 (Carbon monoxide) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (electrooxidn. on ultrathin Pd films deposited on Pt(111) in acid soln.); 7647-01-0 (Hydrochloric acid) Role: OCU (Occurrence, unclassified), OCCU (Occurrence) (of Pt(111) electrtode with ultrathin palladium film in HClO4 soln.contg. trace of HCl); 7440-06-4 (Platinum) Role: DEV (Device component use), USES (Uses) (single crystal; effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.); 1314-08-5 (Palladium oxide PdO) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (underpotential deposition of ultrathin Pd films on Pt(111) in acid soln. contg.)     «

CAN 138:294032 72-8 Electrochemistry Institut fuer Physikalische und Theoretische Chemie, Universitat Bonn, Bonn, Germany. Journal 0039-6028 7440-05-3P (Palladium) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PNU (Preparation, unclassified), PREP (Preparation), PROC (Process) (effect of specific chloride adsorption on electrochem. behavior of ultrathin Pd films deposited on Pt(111) in acid soln.); 16887-00-6 (Chloride) Role: NUU (Other use, unclassified), USES...     »