Electrode Work Function and Absolute Potential Scale in Solid-State Electrochemistry

Publisher Website
Google Scholar
Abstract
A two-Kelvin-probe arrangement was used to measure, for the first time in situ, the work functions, Φ, of the gas-exposed surfaces of porous Pt, Au, and Ag working and reference electrodes exposed to O2­He,O2­He, H2­HeH2­He and O2­H2O2­H2 mixtures, and deposited on 8% Y2O3Y2O3 -stabilized ZrO2ZrO2 (YSZ) in a three-electrode solid electrolyte cell. It was found that at temperatures above 600 K the potential difference, UWR,UWR, between the working (W) and reference (R) electrode reflects the difference in the actual, spillover, and adsorption-modified work functions, ΦWΦW and ΦRΦR of the two electrodes eUWR=ΦW−ΦReUWR=ΦW−ΦR 1 This equation, typically valid over 0.8-1 V wide UWRUWR ranges, was found to hold for any combination of the Pt, Au, and Ag electrodes. It is consistent with the previously reported equation eΔUWR=ΔΦWeΔUWR=ΔΦW 2 which is also confirmed here, and allows for the definition of a natural absolute electrode potential UO2(abs)UO2(abs) in solid-state electrochemistry from UO2(abs)=Φ/eUO2(abs)=Φ/e 3 where Φ is the work function of the gas-exposed electrode surface of the metal (any metal) electrode in contact with the YSZ solid electrolyte. It expresses the energy of solvation of an electron from vacuum to the Fermi level of the solid electrolyte. The value UO20(abs)=5.14±0.05UO20(abs)=5.14±0.05 V was determined as the standard UO2(abs)UO2(abs) value at pO2=1 barpO2=1 bar and T=673T=673 K. © 2001 The Electrochemical Society. All rights reserved.

This publication has 40 references indexed in Scilit: