Strong Impact of Platinum Surface Structure on Primary and Secondary Alcohol Oxidation during Electro-Oxidation of Glycerol

Autor(es)

Garcia, Amanda C. ^{[1, 2]} ; Kolb, Manuel J. ^[1] ; van Nierop y Sanchez, Chris ^[1] ; Vos, Jan ^[1] ; Birdja, Yuvraj Y. ^[1] ; Kwon, Youngkook ^[1] ; Tremiliosi-Filho, Germano ^[2] ; Koper, Marc T. M. ^[1]

Afiliação do(s) autor(es)

^[1] Leiden Univ, Leiden Inst Chem, POB 9502, NL-2300 RA Leiden - Netherlands

^[2] Univ Sao Paulo, Inst Quim Sao Carlos, Ave Trabalhador Sao Carlense 400, BR-13569590 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACS CATALYSIS; v. 6, n. 7, p. 4491-4500, JUL 2016.
• Citações Web of Science: 38

Resumo

Herein we describe a combined experimental and computational study of electrochemical glycerol oxidation in acidic media on Pt(111) and Pt(100) electrodes. Our results show that glycerol oxidation is a very structure-sensitive reaction in terms of activity and, more surprisingly, in terms of selectivity. Using a combination of online HPLC and online electrochemical mass spectrometry, we show that on the Pt(111) electrode, glyceraldehyde, glyceric acid, and dihydroxyacetone are products of glycerol oxidation, while on the Pt(100) electrode, only glyceraldehyde was detected as the main product of the reaction. Density functional theory calculations show that this difference in selectivity is explained by different binding modes of dehydrogenated glycerol to the two surfaces. On Pt(111), the dehydrogenated glycerol intermediate binds to the surface through two single Pt-C bonds, yielding an enediol-like intermediate, which serves as a precursor to both glyceraldehyde and dihydroxyacetone. On Pt(100), the dehydrogenated glycerol intermediate binds to the surface through one double Pt=C bond, yielding glyceraldehyde as the only product. Stripping and in situ FTIR measurements show that CO is not the only strongly bound adsorbed intermediate of the oxidation of glycerol, glyceraldehyde, and dihydroxyacetone. Although the nature of this adsorbate is still unclear, this intermediate is highly resistant to oxidation and can only be removed from the Pt surface after multiple scans. (AU)

• Processo FAPESP: 14/24438-8 - Conversão de álcoois em produtos de valor agregado. um estudo mecanístico em eletrodos mono cristalinos
• Beneficiário: Amanda Cristina Garcia
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado