Ethanol oxidation on shape-controlled platinum nanoparticles at different pHs: A combined in situ IR spectroscopy and online mass spectrometry study

Abstract

Ethanol oxidation on different shape-controlled platinum nanoparticles at different pHs was studied using electrochemical, Attenuated Total Reflection -Fourier Transform Infrared Spectroscopy (ATR-FTIR) and, especially, Differential Electrochemical Mass Spectrometry (DEMS) techniques, which gives interesting quantitative information about the products of ethanol oxidation. Two Pt nanoparticle samples were used for this purpose: (100) and (111) preferentially oriented Pt nanoparticles. The results are in agreement with previous findings that the preferred decomposition product depends on surface structure, with COads formation on (100) domains and acetaldehyde/acetic acid formation on (111) domains. However, new information has been obtained about the changes in CHx and CO formation at lower potentials when the pH is changed, showing that CHx formation is favored against the decrease in CO adsorption on (100) domains. At higher potentials, complete oxidation to CO2 occurs from both CHx and CO fragments. In (111) Pt nanoparticles, the splitting of C-C bond is hindered, favoring acetaldehyde and acetate formation even in 0.5 M H2SO4. C1 fragments become even less when the pH increases, being nearly negligible in the highest pH studied.

Well‐Defined Platinum Surfaces for the Ethanol Oxidation Reaction

“…Regarding monometallic catalysts, Feliu and coworkers studied the ethanol oxidation in acid media on different shape‐controlled platinum nanoparticles: (100) and (111) predominantly oriented Pt nanoparticles with a preferential cubic and octahedron shape, respectively . FTIRS and DEMS studies demonstrated that the C−C bond breaking was more favored on cubic Pt NPs (2B in Scheme ), in agreement with the aforementioned results with Pt single crystals.…”

“…Whereas only the synthesis of monometallic high‐index facets NPs has been reported by using electrochemical methods, by the use of chemical methods have been reported also the synthesis of not only high‐index but also low‐index monometallic, bimetallic and trimetallic NPs, such as cubic, octahedral and rhombic dodecahedral NPs with predominantly {100}, {111} and {110} facets, respectively …”

Electrocatalytic Oxidation of Glycerol on Platinum Single Crystals in Alkaline Media

“…Moreover, the direct correlation from the displayed result between the Pt(poly) and the Pt( hkl ) surfaces is not straightforward simple because once the most active surface domain starts oxidizing the organic molecule, the solution concentration changes for neighbor domains, which will activate at higher potentials. However, it can be used to understand its behavior and to prepare catalysts with predetermined surface orientation so that activity is maximized …”

Addition of iron oxide to Pt-based catalyst to enhance the catalytic activity of ethanol electrooxidation

“…3 (FTIR) [39][40][41][42][43], and High Performance Liquid Chromatography (HPLC) [16,44,45], which have helped to identify the reaction products. Acetaldehyde and acetic acid always emerge as the main products and reflect the stability of the C-C bond at lower DAFC operating temperatures 80-100 o C.…”