Oxidation of formaldehyde and ethanol on Au(1 1 1) and Au(1 1 1) modified by spontaneously deposited Ru in sulfuric acid solution

• Published in: Electrochimica acta Vol. 54; no. 23; pp. 5408 - 5412
• Main Authors: Strbac, S., Avramov Ivic, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 30.09.2009; Elsevier
• Subjects: Anodic; Chemistry; Deposition; Electrochemistry; Ethanol; Ethyl alcohol; Exact sciences and technology; Formaldehyde; General and physical chemistry; Islands; Kinetics and mechanism of reactions; Oxidation; Scanning tunneling microscopy; Spontaneous deposition; Oxidation; Ru; Au; Ethanol; Spontaneous deposition; Formaldehyde; Gold; Ruthenium; Crystal orientation; Alcohol; Transition metal; Aldehyde; Single crystal; Acidic solution; Sulfuric acid; Surface structure; Electrodes; Scanning tunneling microscopy; Morphology; Electrochemical reaction; Platinoid; Organic compounds; Modified material
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2009.04.031

The oxidation of formaldehyde and ethanol on both pure Au(1 1 1) and Au(1 1 1) modified by approximately 0.3 monolayer (ML) of spontaneously deposited Ru was studied by cyclic voltammetry (CV) in 0.5 M H 2SO 4 solution containing either 0.25 M formaldehyde or 0.35 M ethanol. In situ scanning tunneling microscopy (STM) and CV were employed to characterize the Au(1 1 1) and Ru/Au(1 1 1) surfaces. The oxidation of HCHO on Ru/Au(1 1 1) commences at 0.1 V more negative potential than on pure Au(1 1 1). From 0.25 to 0.55 V vs. (Ag/AgCl), the reaction occurs with increasing current, showing a peak at a potential of 0.43 V. It is assumed that the increasing anodic activity of the Ru/Au(1 1 1) surface is associated with the oxidation of some reaction intermediates, facilitated by the presence of Ru in its metallic state. On the other hand, the oxidation of ethanol on Ru/Au(1 1 1) commences at 0.1 V more positive potential than on pure Au(1 1 1), and proceeds in the potential region from 0.2 to 0.5 V with significantly smaller currents, showing a peak at 0.43 V. This inhibiting effect is explained by the deactivation of the most active Au(1 1 1) step sites by high coverage with Ru islands. The appearance of a small peak at 0.43 V is most likely associated to the oxidation of some intermediates during ethanol oxidation at the Ru/Au step sites formed on the Au(1 1 1) terraces by the presence of a small coverage with Ru islands.