Diamond thin film electrodes possess unique properties, like high chemical and mechanical stability, a very large window of electrochemical polarization and, interestingly, they can be heated up to around 500°C under oxygen, without important modification. These features suggest the use of conductive silicon-supported diamond films as ideal supports for the preparation of other electrode materials, overcoming the strong interactions commonly due to metal support passivation. Accordingly, different quantities of RuO2 and IrO2 were deposited on diamond electrodes, following the common sol-gel procedure. Amounts were close to the monolayer requirement, saying from 1E+13 to about 1E+16 MO2 “molecules” per square centimeter. Considering that ruthenium dioxide is the main component of DSA® for chlor-alkali industry, electrochemical characterization was carried out by cyclic voltammetry and quasi-steady state polarizations, in presence of NaCl. Moreover, ex-situ measurements were done using AFM and XPS techniques. The CV curves obtained for two different concentration of RuO2 are reported in comparison with the Si/BDD material as prepared. While the lowest modification seems to have no catalytic activity for the chlorine evolution reaction, the expected features of ruthenium dioxide are, on the contrary, clearly identified. Notwithstanding the small amount of oxide at the diamond surface (from XPS measurement, the ratio Ru/C is about 1/114), two well-resolved pairs of peaks can be related to the “literature-predicted” solid-state transitions (RuII/RuIII and RuIII/RuIV). From the XPS measurements, two different types of carbon can be found at the diamond surface. The angle resolved technique applied on a region depth of about 30Å, shows the concomitant presence of diamond-like carbon and a “disordered” form, most likely related to different oxidation states (sp2 and/or hydroxylated carbon).
Surface Modifications at Si/BDD: Spontaneous and Induced Phenomena
FERRO, Sergio;DAL COLLE, Maurizio;DE BATTISTI, Achille
2000
Abstract
Diamond thin film electrodes possess unique properties, like high chemical and mechanical stability, a very large window of electrochemical polarization and, interestingly, they can be heated up to around 500°C under oxygen, without important modification. These features suggest the use of conductive silicon-supported diamond films as ideal supports for the preparation of other electrode materials, overcoming the strong interactions commonly due to metal support passivation. Accordingly, different quantities of RuO2 and IrO2 were deposited on diamond electrodes, following the common sol-gel procedure. Amounts were close to the monolayer requirement, saying from 1E+13 to about 1E+16 MO2 “molecules” per square centimeter. Considering that ruthenium dioxide is the main component of DSA® for chlor-alkali industry, electrochemical characterization was carried out by cyclic voltammetry and quasi-steady state polarizations, in presence of NaCl. Moreover, ex-situ measurements were done using AFM and XPS techniques. The CV curves obtained for two different concentration of RuO2 are reported in comparison with the Si/BDD material as prepared. While the lowest modification seems to have no catalytic activity for the chlorine evolution reaction, the expected features of ruthenium dioxide are, on the contrary, clearly identified. Notwithstanding the small amount of oxide at the diamond surface (from XPS measurement, the ratio Ru/C is about 1/114), two well-resolved pairs of peaks can be related to the “literature-predicted” solid-state transitions (RuII/RuIII and RuIII/RuIV). From the XPS measurements, two different types of carbon can be found at the diamond surface. The angle resolved technique applied on a region depth of about 30Å, shows the concomitant presence of diamond-like carbon and a “disordered” form, most likely related to different oxidation states (sp2 and/or hydroxylated carbon).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
