Studies of adsorption at well-ordered electrode surfaces using low energy electron diffraction

Conference · Thu Oct 01 00:00:00 EDT 1981

OSTI ID:5886258

Ross, Jr, P N

There are electrochemical reactions where the rate determining step is not an electron transfer step, but a purely chemical step, such as chemisorption. This is the case, for example, in the classic hydrogen electrode reaction, H/sub 2/ ..-->.. 2H/sup +/ + 2e/sup -/, where for the Pt group metals the rate is determined by the rate of dissociative chemisorption of hydrogen. In reactions of this type, one is seeking virtually identical information about the adsorbed state as in heterogeneous catalysis, with the additional complication of the solution phase. Thus, studies of adsorbed states have the same important relationship to physical understanding of reaction paths and kinetics in both gas-solid and electrochemical catalysis. A number of research groups that study the electrode-electrolyte interface have developed ex-situ methods for this study. X-ray photoelectron spectroscopy (XPS) has been used extensively for ex-situ analysis of electrode surfaces but not for the study of adsorbed or submonolayer electrodeposited species. In this review, studies of submonolayer structures on electrode surfaces using the combination of classical electrochemical methods with low energy electron diffraction (LEED) are described. It is shown that by use of this combination of techniques the enthalpy and entropy of adsorption onto well-ordered surfaces can be determined directly. The effect of imperfections in the surface on adsorption enthalpy can be readily determined using stepped surfaces (i.e. ordered periodic imperfections). The variation of enthalpy and entropy with coverage on structurally homogeneous surfaces can provide insight into substrate-adsorbate and adsorbate-adsorbate interactions.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5886258
• Report Number(s): LBL-13507; CONF-8108102-1; ON: DE82005256
• Resource Relation: Conference: 5. international summer institute for surface sciences, Milwaukee, WI, USA, 23 Aug 1981
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ELECTRODEPOSITION
THERMODYNAMICS
HYDROGEN
ADSORPTION
CATALYSIS
ELECTRODES
ELECTRON DIFFRACTION
ENTHALPY
ENTROPY
PLATINUM
COHERENT SCATTERING
DEPOSITION
DIFFRACTION
ELECTROLYSIS
ELEMENTS
LYSIS
METALS
NONMETALS
PHYSICAL PROPERTIES
PLATINUM METALS
SCATTERING
SORPTION
SURFACE COATING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
400400* - Electrochemistry