Heterojunctions of Graphene/Nanoparticles: a GISAXS Characterization.

MARÍA CELESTE DALFOVO; C. HUCK IRIART; V. STANIC; L. J. GIOVANETTI; F.G. REQUEJO; F.J. IBAÑEZ

Campinas

Workshop; Recent Developments in Sybchrotron Radiation.; 2015

LNLS/CNPEM

Graphene (G) was the first two-dimentional (2D) crystalline material isolated and characterized. This new nanocarbon exhibited unusual and unique chemical and electronic properties compared to its conterpart, graphite.[1] This fascinating discovery was aworded in 2010 with a Novel Prize in Physics honoured to A. Geim and K. Novoselov. Since then, the scientific community is actively working in the development of different types of 2D structures that can mimic graphene´s attributes. Heterojunctions formed by a combination of G with metal nanoparticles (NPs) are a new class of nanomaterials that can be used in chemical/biological sensing,[2] catalysis, optoelectronics,[3] and surface-enhanced Raman scattering (SERS)[4] applications for just to mention a few. However, the structure and conformation of these heterojuntions should be explored more in detail in order to develop future applications.[5] In this work we chemically synthesized alkylamine- and alkylthiol-coated Au nanoparticles (NPs) and assemble them as films on graphene and silicon substrates. We perform Grazing-incidence small-angle X-ray scattering (GISAXS) experiments in order to monitor the NPs assembly (i.e: order and structure), internanoparticle distance, and thermal stability of these films. We also explore the use of dithiol molecules in order to improve NPs correlation and control the internanoparticle distance. Interesting preliminary results showed that graphene (substrate) and dithiol linkers provide correlation to those NPs. The increase in temperature during thermal treatment leads to the loss of NPs correlation likely caused by NPs annealing and film colapsing. [1] K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, A. A. Firsov, Science 2004, 306, 666.[2] Z. Fan, R. Kanchanapally, P. C. Ray, J. Phys. Chem. Lett. 2013, 4, 3813.[3] Minhyeok Choe, Chu-Young Cho, Jae-Phil Shim, Woojin Park, Sung Kwan Lim, et, Appl. Phys. Lett. 2012, 101, 031115.[4] M. C. Dalfovo, G. I. Lacconi, M. A. Moreno, M. C. Yappert, G. U. Sumanasekera, R. C. Salvarezza, F. J. Ibañez, ACS Appl. Mater. Interfaces 2014.[5] V. Vale?, J. Vejpravová, B. Pacáková, V. Holý, S. Bernstorff, M. Kalbáč, Phys. Status Solidi B 2014, n/a.