Anodic oxidation of methyl formate and its relationship to the reactions of methanol and formic acid

Enhancement of the oxidation of methyl formate at multifunctional electrocatalyst composed of Pt/Pd and Pt/Ru nanoparticles

“…Indeed, at potentials more negative than ca. 0.2 V, adsorption of hydrogen onto Pt (or Pt/Ru or Pt/Pd) nanoparticles takes place [6,9,13,19,22]. That reaction is sequentially followed by the electrochemical or chemical desorption steps on Pt, its interactions with WO 3 matrix [27], leading to hydrogen ''spillover'' within WO 3 and, finally, to hydrogen evolution.…”

“…Regardless the detailed reaction mechanism, the platinum component shows appreciable reactivity towards C-H bond breaking, but the ruthenium addition is expected to activate more readily water molecules on the metal surface and to produce Ru oxo species capable of interacting with the poisoning chemisorbed CO intermediate, a byproduct of the methanol oxidation at Pt, to yield the final product, CO 2 [12][13][14][15][16][17]. Also the electrooxidation of formic acid at Pt/Pd nanoparticle catalyst has been demonstrated to be a promising anodic process for fuel cell technology [18][19][20][21][22][23]. The formic acid oxidation proceeds via so-called dual path mechanism comprising direct fast formation of CO 2 in addition to the generation of CO intermediate.…”

“…Thus, when compared to methanol, the extent of CO-poisoning is less pronounced and the anodic current densities are higher in the case of formic acid. More recently, oxidation of methyl formate, a volatile ester with low boiling temperature (31.5°C), has been considered [19], and its relationship to the reactions of methanol and formic acid has been described. An important issue is that the electrooxidation of methyl formate (CH 3 OCOH) involves ideally eight electrons per molecule to produce carbon dioxide.…”

“…The ester molecule consists of two (methanolic and formate) components, and the overall oxidation mechanism requires breaking of different bonds around two carbon atoms. It has been postulated that the formate component of the ester is oxidized more rapidly than methanolic component, and electrooxidation of methyl formate proceeds at Pt/Ru via formation of methanol [19]. By analogy to methanol and formic acid, the problem of poisoning by CO exists during oxidation of methyl formate.…”

“…While Pt/Ru is expected to induce oxidation of both the methanolic [1][2][3][4][5][6][7][8][9][10][11] and formate [19] parts of the ester, the Pt/Pd binary system should be particularly effective during electrooxidation of formate or formic acid [18][19][20][21][22][23]. Historically, various forms of the latter catalyst were considered: Pt/Pd alloys [24], Pd ''decorated'' polycrystalline Pt surfaces [22] and Pt nanoparticles modified with palladium [25].…”