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Campus de Excelencia InterncionalCampus of International Excellence

Surface chemical reactions at epitaxial graphene and material beyond graphene

Fechas celebración

Desde el 12-09-2017 hasta el 12-09-2017

Hora Celebración

12 h

Lugar Celebración

Dpto. Física de la Materia Condensada, Facultad Ciencias, Modulo 3, Sala de Seminarios (5ª Planta)

Descripción

Abstract:  

In this talk, an overview of surface-science investigations on the chemical reactivity of epitaxial graphene (Gr) and materials “beyond graphene” (van der Waals semiconductors, topological insulators, Dirac semimetals, Weyl semimetals) will be provided.

 

By means of time-resolved X-ray photoemission spectroscopy and high-resolution electron energy loss spectroscopy, different surface chemical reactions in epitaxial Gr have been followed in real time (Gr growth by cracking of hydrocarbons, oxidation, intercalation of chemical species).

In particular, we have observed that, due to the similar work functions, Gr grows as an undoped sheet on the Pt-skin of Pt3Ni(111) but in an oxygen environment Ni segregation toward the surface occurs with selective oxidation of Ni. Subsequently, the Pt skin underneath Gr is replaced by a nickel-oxide skin. In the oxidation process, Gr acquires a p-type doping of 0.3 eV [1].

We have also used surface-science tools for investigating Gr employment in the fields of energy and catalysis. By means of a combination of surface-science spectroscopies and density functional theory [2], we have unveiled the mechanisms ruling the catalytic role of epitaxial Gr grown on transition-metal substrates for the production of hydrogen from water. Water decomposition at the Gr/metal interface at room temperature provides a hydrogenated Gr sheet, which is buckled and decoupled from the metal substrate. Molecular hydrogen is released upon heating above T=400 K.

 

Moreover, the analysis of the chemical reactivity of surface defects of two-dimensional materials provides important information for the nanofabrication process of electronic devices with active channels of ultrathin flakes of black phosphorus (few-layer phosphorene) [3] or InSe [4], which require the use of capping layers in order to avoid surface degradation in ambient conditions. In particular, we find high reactivity of phosphorene toward water, oxygen and CO [5], while water decomposition at room temperature occurs at Se vacancies of InSe [4].

 

Furthermore, the chemical inertness of high-quality single crystals of topological insulators toward ambient gases [6] will be discussed. The subsequent ambient stability of uncapped topological insulator-based nanodevices [7] paves the way for the technological exploitation of topological insulators in the fields of plasmonics [8] and Terahertz photodetection [7].

Finally, surface-science investigations on the chemical reactivity of Weyl semimetals and Dirac semimetals, also highlighting their potential applications in catalysis, will be presented.

References

 

[1]         A. Politano and G. Chiarello, 2D Mater. 4 (2017) 035003.

[2]          A. Politano et al., ACS Nano 10 (2016) 4543.

[3]          L. Viti et al., Adv. Mater. 27 (2015) 5567; L. Viti et al., Adv. Mater. 28 (2016) 7390.

[4]          A. Politano et al. Nanoscale 8 (2016) 8474.

[5           A. Politano et al., Nano Res. 9 (2016) 2598.

[6]          A. Politano et al., J. Phys. Chem. C 118 (2014) 21517.

[7]           L. Viti et al., Nano Lett. 16 (2016) 80; A. Politano et al. APL Mater. 5 (2017) 035504.

[8]          A. Politano et al., Phys. Rev. Lett. 115 (2015) 216802.

Más información: http://www.ifimac.uam.es/category/seminars/

 

 

Agentes y colaboradores

  • Universidad Autónoma de Madrid
  • CSIC
  • ASEYACOVI
  • ACENOMA
  • AICA
  • Centro de Microanálisis de Materiales (CMAM)
  • Centro de Investigación en Física de la Materia Condensada (IFIMAC)
  • CBMSO - Centro de Biología Molecular Severo Ochoa
  • CIAL - Centro de Investigación en Ciencias de la Alimentación
  • CNB - Centro Nacional de Biotecnología 
  • Centro de Iniciativas Emprendedoras (CIADE)
  • Cámara de Madrid
  • FEMAN
  • Fundación Universitaria Autónoma de Madrid
  • ICMAT - Instituto de Ciencias Matemáticas
  • ICMM - Instituto de Ciencia de Materiales de Madrid
  • ICP - Instituto de Catálisis y Petroquímica
  • ICV - Instituto de Cerámica y Vidrio
  • IFT - Instituto de FísicaTeórica
  • IIBM - Instituto de Investigaciones Biomédicas Alberto Sols
  • IMDEA - Alimentación
  • IMDEA - Nanociencia
  • IMM - Instituto de Microelectrónica de Madrid
  • InNorMadrid
  • Parque Científico de Madrid
  • Oficina de Transferencia de Resultados de la Investigación (OTRI) de la UAM
  • Facultad de Ciencias
  • Facultad de Ciencias Económicas y Empresariales
  • Facultad de Derecho
  • Facultad de Filosofía y Letras
  • Facultad de Medicina
  • Facultad de Formación de Profesorado y Educación
  • Facultad de Psicología
  • Escuela Politécnica Superior
Proyecto realizado con ayudas concedidas por el Ministerio de Economía y Competitividad / EXPEDIENTE: CEI10-1-0009 CEI UAM+CSIC: INNOCAMPUS 2010 Proyecto financiado por el Ministerio de Educación, Cultura y Deporte, y el Ministerio de Economía y Competitividad en el marco del Programa Campus de Excelencia Internacional/ EXPEDIENTE: CEI10-1-0009 CEI UAM+CSIC: INNOCAMPUS 2010