The state of electrodeposited hydrogen at ruthenium electrodes

Abstract

Electrochemical measurement of H accommodation at noble metal electrocatalyst surfaces is important for evaluation of real areas of electrode preparations and hence of intrinsic electrocatalytic properties; it is also required for evaluation of the relative degrees of surface oxidation of noble metals under anodic conditions. Experiments are described which show that a region of underpotential deposition and ionization of adsorbed H atoms is difficult to define at Ru electrodes due to (a) H sorption into the metal and (b) overlap with surface oxidation and reduction processes owing to the fact that Ru surfaces already begin to be oxidized near to, or in, the potential region where H atom deposition and ionization processes occur. It is shown that some conclusions reached in other work on the state of electrodeposited H at Ru may have to be revised. In the presence of the Cl' ion, which is strongly adsorbed at Ru, the behavior of Ru electrode surfaces in cyclic voltammetry becomes more like that of Pt.

Flexible ruthenium oxide-activated carbon cloth composites prepared by simple electrodeposition methods

“…Besides, the small peak at 284.88 eV can be attributed to C-1s peak from graphite-like carbon atoms [42]. The above results indicate the existence of ruthenium dioxide (RuO 2 and RuO 2 .xH 2 O) and some amount of Ru(0) on the surface of the freshly prepared composites, in agreement with previous studies [17, [43][44][45]. The presence of these hydrous ruthenium oxides is expected to improve the electrochemical reversibility and conductivity of the flexible composites.…”

“…6 for the electrode prepared by the potentiostatic method is similar to that reported for a thin film of ruthenium oxide [35,[43][44][45]. On the positive 11 scan direction it can be observed the hydrogen region in which the ionization of adsorbed hydrogen atoms overlaps with the adsorption of water on ruthenium atoms [43,44] Besides, proton diffusion into defect sites, interstitial sites, and/or grain boundaries is also taking place in this potential region [47]. Table 3 shows the values of specific capacitance obtained for all the composites prepared by chronoamperometry (electrodes 1 to 4), cyclic voltammetry (electrode 5 and 6) and chronopotentiometry (electrode 7 to 9) techniques.…”

“…0.2 V can be distinguished during the reverse scan. This peak is usually associated with the partial oxide film reduction [44].…”

Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors

“…Ruthenium oxide and RuO 2 xH 2 O can be oxidized and reduced reversibly through electrochemical protonation. 14,15 RuO 2 ϩ ␦H ϩ ϩ ␦e…”

Study of CO Oxidation on Well-Characterized Pt-Ru/C Electrocatalysts Having Different Composition

“…Those results indicate that the apparent electrocatalytic activity of the PtRu/C alloy catalyst is far superior to that of Pt/C (E-TEK). This better performance of the PtRu/C alloy catalyst can be explained by a bifunctional mechanism for oxidation of CO. 28,29 Since adsorption of oxygenated species onto Ru commences at more negative potential than on Pt, 45,46 oxygenated species are supplied to the PtRu/C alloy catalyst at low potential, thereby facilitating the onset of the oxidation of CO to CO2 at a potential significantly more negative than on Pt/C. This effect leads to the higher activity for the electrooxidation of adsorbed CO on PtRu/C compared to Pt/C as shown in Figure 5a.…”