Electrochemical Behavior of Benzaldehyde on Polycrystalline Platinum. An in Situ FTIR and DEMS Study

Abstract

The reactions of benzaldehyde at platinum in 0.1 M HClO4 were studied by means of differential electrochemical mass spectrometry (DEMS) and in situ Fourier transform infrared (FTIR) spectroscopy combined with cyclic voltammetry. With the application of DEMS, it was established that this compound oxidizes completely to CO2 at E > 0.60 V (RHE) and reduces to toluene, benzene, and cyclohexane in the potential region for hydrogen adsorption and H2 evolution. No partial or total hydrogenation of toluene was observed. In situ FTIR measurements show that the oxidation of benzaldehyde also produces adsorbed benzoate ions (band at 1376 cm-1) at about 0.60 V (RHE), which are protonated to benzoic acid (band at 1273 cm-1) upon desorption at E > 1.0 V (RHE). The assignment is confirmed by FTIR experiments with benzoic acid. Fragmentation of benzaldehyde during adsorption is confirmed by the presence of vibration bands at 2002 and 1807 cm-1 assigned to lineal and bridge bonded CO, respectively, and at 1240 cm-1 due to (COH)ad. The results are compared with previous studies on the reactivity of benzyl alcohol, benzoic acid, toluene, and benzene.

Spectroscopic evidence for intermediate species formed during aniline polymerization and polyaniline degradation

“…The cell and experimental arrangements were described previously. 44 A sketch of the set-up is depicted in ref. 18 The electrochemistry inside the in situ FTIR cell is made in thin layer conditions, due to the proximity of the electrode towards the window necessary to minimize water IR absorption.…”

Study of the electrochemical oxidation process of 3,4-(methylenedioxy)phenylmethanol in non-aqueous solvents

“…Taking into account the similar structures between piperonyl and benzyl alcohol it is possible that this mechanism take place during the oxidation process of piperonyl alcohol. On other hand, Planes et al [26] pointed out that these processes occur at less positive potentials that the ones observed for the oxidation process of species in solution (E > 0.6 V vs RHE). Due to the fact that these reactions are linked to adsorbed species, the currents associated to these reactions are very low and are not visible on the voltammograms.…”

“…The formation of adsorbed species like CO from the electrochemical oxidation of benzyl alcohol and benzaldehyde was reported by Planes et al, using DEMS (Differential Electrochemical Mass Spectrometry). [26].…”

“…The dissociative adsorption of the benzyl alcohol and benzaldehyde produces the formation of adsorbed CO (decarbonilation), carbon dioxide, benzene, toluene and cyclohexane [26]. Taking into account the similar structures between piperonyl and benzyl alcohol it is possible that this mechanism take place during the oxidation process of piperonyl alcohol.…”

Structure Sensitivity of Acetophenone Reduction on Palladium-Modified Platinum Single-Crystal Electrodes

“…36 A discrepancy was found between the oxidative charge of Bz obtained on Pt(100), being much higher (around 1600 μC•cm −2 ), though it must be noted that for Bz, this was not a stripping charge, but a charge obtained with Bz in solution. 36 Considering these values, and assuming that the adsorbates and their electro-oxidation residues only evolve into carbon dioxide (as it was considered for Bz, 36 toluene, benzyl alcohol, 37 and benzaldehyde 38 ), we conclude that AP is irreversibly adsorbed in an essentially flat mode on Pd ML Pt-(111) and Pd ML Pt(100), while the atypical low electrooxidation charge on Pd ML Pt(110) might suggest (a) a lower quantity of pre-adsorbed AP or (b) a different orientation at the surface which perhaps allows only a part of the molecule to be oxidized. Density functional theory calculations 39 for Bz on Pt low-index surfaces show that interaction is dominated by van der Waals interactions, and that adsorption is the strongest on unreconstructed Pt(110).…”