Photo‐electrochemical Oxidation of Organic C1 Molecules over WO₃ Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation

Abstract

To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed.

Photoinduced Pt/BiVO4/Bi2O3 Heterostructures for Methanol Oxidation and New Insights on the Photo-/Electrocatalysis Coupling Mechanism

“…The non-CO ad pathway of formic acid oxidation in an acidic electrolyte has been proposed on a Pt thin-film electrode and a monoclinic WO 3 photoanode by Behm et al, based on the in situ spectro-/ electrochemical and online differential electrochemical mass spectroscopy studies, and it was found that formic acid could be photo-/electrooxidized to CO 2 with a selectivity of as high as 90%. 60,61 To elucidate how the dehydrogenation of methanol on Pt/ BiVO 4 /Bi 2 O 3 is promoted under irradiation is crucial for understanding the photo-/electrocatalysis mechanism. It is well accepted that methanol dehydrogenation in an alkaline environment is strongly promoted by the OH ad on the Pt surface.…”

Recent Progress on Photo‐Promoted Alcohol Electrooxidation for Fuel Cells

“…Also, they found the formaldehyde as the incomplete oxidation product prevails for the methanol oxidation. [ 94 ]…”

“…Also, they found the formaldehyde as the incomplete oxidation product prevails for the methanol oxidation. [94] WO 3 , TiO 2 , SnO 2 , and so on have also been proposed as one of the components in electrocatalysts to alleviate the "notorious" CO ads poisoning to the Pt catalysts. The intrinsic cause was tentatively ascribed to the strong metal and support (metal oxides) interaction (SMSI) effect between oxides and Pt, which leads to a weakened adsorption of CO ads on Pt surface.…”

Releaving Refractory Oxidized Organic Pollutants by Photoelectrochemical Treatment Using Formic Acid as Solvent

“…Of course, like all simple C 1 and C 2 compounds and -anions photoelectrochemical as well as electrochemical transformations of HCOOH were investigated before (e.g. Reichert et al [8] and quotations in this paper), with a focus on fuel-cell use of formic acid (Okamoto et al [7]). It turned out that neat HCOOH cannot be oxidized at Pt anodes without some water being present (ibid.…”