Interplay of non-uniform charge distribution on the electrochemical modification of graphene

Autor(es)

Macedo, Lucyano J. A. ^[1] ; Lima, Fitipe C. D. A. ^[2] ; Amorim, Rodrigo G. ^[3] ; Freitas, Raul O. ^[4] ; Yadav, Anur ^{[5, 6]} ; Iost, Rodrigo M. ^{[5, 6]} ; Balasubramanian, Kannan ^{[5, 6]} ; Crespilho, Frank N. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, BR-13560970 Sao Paulo - Brazil

^[2] Fed Inst Educ Sci & TechnolSao Paulo, Campus Matao, BR-15991502 Sao Paulo - Brazil

^[3] Fluminense Fed Univ, Dept Phys, BR-27213145 Rio De Janeiro - Brazil

^[4] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, Campinas, SP - Brazil

^[5] Humboldt Univ, Sch Analyt Sci Adlershof SALSA, Dept Chem, D-10099 Berlin - Germany

^[6] Humboldt Univ, IRIS Adlershof, D-10099 Berlin - Germany

• Tipo de documento: Artigo Científico
• Fonte: NANOSCALE; v. 10, n. 31, p. 15048-15057, AUG 21 2018.
• Citações Web of Science: 3

Resumo

Graphene is considered a model material for surfaces because it is stable despite being composed of a single layer of carbon atoms. Although the thermal and electronic properties of graphene are well reported, the behavior of graphene sheets with the addition of charges to the structure is not well understood. Combining infrared spectroscopy, electrochemical analysis, and computational simulations, we report the effect of an electrochemically induced covalent anchoring of 4-carboxyphenyl (4-CP) units on the optical and electronic properties of graphene. Charges in graphene become concentrated at specific sites of the sheet when electrochemically perturbed and the functionalization occurs inhomogeneously along the graphene sheet. We observed that, when graphene is covalently functionalized, the resistance to heterogeneous electron transfer is increased by a factor of 1.4. Furthermore, scattering-type scanning near-field optical microscopy and atomic force microscopy show that the covalent functionalization affects drastically the optical and physical properties of the graphene/SiO2 system, especially the plasmon-phonon coupling after the functionalization. In addition, from these we infer that a comparatively higher degree of functionalization occurs near the electrode edges. These results are supported by computational simulations, which show that the covalent anchoring of 4-CP units weakens electron transfer because the charges are retained on the sp(3)-hybridized carbon atoms generated upon functionalization, suggesting that graphene properties are deeply influenced by the way the molecules are immobilized on its structure. (AU)

• Processo FAPESP: 13/14262-7 - Filmes nanoestruturados de materiais de interesse biológico
• Beneficiário: Osvaldo Novais de Oliveira Junior
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/16672-3 - Desenvolvimento de Bioeletrodos de Alto Desempenho para Miniaturização de Biocélulas a Combustível
• Beneficiário: Frank Nelson Crespilho
• Modalidade de apoio: Auxílio à Pesquisa - Regular