Pt Nanoelectrodes Sealed in Quartz Capillaries Modified with Underpotential‐Deposited Bismuth for Formic Acid Electrooxidation

• Published in: ChemElectroChem Vol. 9; no. 18
• Main Authors: Battistel, Dario, Citron, Alberto, Veclani, Daniele, Daniele, Salvatore
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 27-09-2022
• Subjects: Adatoms; Aqueous solutions; Bismuth; Bismuth UPD; Blood vessels; Capillaries; Carbon monoxide poisoning; Electrodes; Formic acid; Formic acid electrooxidation; Fuel cells; Hydrogen UPD; Microelectrodes; Platinum nanoelectrodes; Quartz; Quartz capillaries; Species diffusion; Sulfuric acid; Surface area; Underpotential deposition
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202200754

Platinum disk nano‐ and micro‐electrodes with radii in the range 40 nm–12.5 μm were fabricated using quartz capillaries and the laser‐puller assisted approach. The hydrogen underpotential deposition (H‐UPD), performed in a 0.5 M H2SO4 aqueous solution, revealed that the nanoelectrodes, with radii of 160 nm and less, displayed extraordinarily large surface areas, which in terms of roughness factors (RFs, i. e., the ratio of the real surface areas to the geometric surface areas) were in the range 1030–3600. This finding was attributed to diffusion of adsorbed species at the Pt/quartz interface along portions of the Pt wires sealed within the glass. RFs between 2 and 3 were instead found at the microelectrodes. Similar results were also obtained with underpotential‐deposited metallic bismuth. In this case, diffusion of Bi adatoms onto the Pt surface was hindered to some extent, providing a RF value of 172. Bi‐modified Pt nano‐ and micro‐electrodes were employed to study the electrooxidation of HCOOH, which is of interest in the field of fuel cells. It was found that the nanoelectrode displayed higher activity towards the electrooxidation of HCOOH and tolerance to CO poisoning, compared to the microelectrode.
Enhancing real surface area: Pt disk nanoelectrodes, sealed in quartz capillaries by the laser‐pulled assisted procedure, display in 0.5 M H2SO4 real surface areas extraordinarily larger than the corresponding geometric ones. This is due to diffusion of adsorbed species at the Pt/quartz interface along portions of the Pt wires sealed inside the glass. Although to a lesser extent, this phenomenon also occurs with under‐potential deposited metallic bismuth. The Bi‐loaded Pt nanoelectrodes are employed to probe the electrooxidation of HCOOH.