291 * To whom all correspondence should be sent: E-mail: ashalaby2011@gmail.com © 2015 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria Bulgarian Chemical Communications, Volume 47, Number 1 (pp. 291–295) 2015 Structural analysis of reduced graphene oxide by transmission electron microscopy A. Shalaby 1, 2 *, D. Nihtianova 3, 4 , P. Markov 4 , A. D. Staneva 2 , R. S. Iordanova 4 , Y. B. Dimitriev 2 1 Science and Technology Center of Excellence, Cairo-Egypt 2 University of Chemical Technology and Metallurgy, 8 Kl. Ohridski blvd., 1756 Sofia, Bulgaria, E-mail: yanko@uctm.edu 3 Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 107, 1113 Sofia, Bulgaria 4 Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, G. Bonchev str., bld. 11, 1113 Sofia, Bulgaria Received December, 2014; Revised January, 2015 Graphene has attracted scientific interest in recent years due to its unique properties. Reduced graphene oxide (RGO) was prepared by chemical oxidation of purified natural graphite to obtain graphite oxide then the material was exfoliated to reduced graphene nanosheets by ultrasonication and reduction process using sodium borohydride (NaBH 4 ). The transmission electron microscopy (TEM) investigations were performed on a TEM JEOL 2100 instru- ment at an accelerating voltage of 200 KV. The measurements of lattice-fringe spacing recorded in High Resolution Transmission Electron Microscopy (HRTEM) micrographs were made using digital image analysis of reciprocal space parameters. The analysis was carried out by the Digital Micrograph software. The obtained selected area elec- tron diffraction (SAED) data show unambiguously that the sample RGO is different from Graphite 2H PDF 75-1621 and has typical interplanar distance d 002 from 3.586 Å up to 4.016 Å. Lattice fringes obtained by HRTEM method also give additional information about interplanar distance d 002 for RGO materials where the value is 3.850 Å. It was established that the main phase is RGO but some impurities of Graphite is also found. Key words: Reduced Graphene Oxide, Structural analysis, TEM analysis. INTRODUCTION Reduced graphene oxide (RGO) is one of the exciting topics in many research fields especially in the field of nanotechnology during the last few years. It has different names such as chemically modified graphene, functionalized graphene, chem- ically converted graphene, or simply graphene. RGO has excellent electrical, thermal and mechani- cal properties [1, 2]. It is a very promising material for many applications, such as in the development of energy-storage capacitors [3–5], field-effect tran- sistors [6], energy-related materials [7], sensors [8], heavy metal removal [9], drug delivery [10] and bi- omedical applications [11]. Generally graphene can be produced by top-down or bottom-up approach- es. The common methods include mechanical or chemical exfoliation of graphite, epitaxial growth on SiC and chemical vapor deposition on metal sur- faces [12–15]. These methods can produce graph- ene with a relatively perfect structure and excellent properties. The most popular method which consid- ered a promising route to achieve mass production with low cost is the chemical method for producing graphene sheets from natural graphite [16]. Graphite is available in large quantities from natural sources and consists of a stack of flat graphene sheets held together by weak van der Waals forces [17]. By us- ing highly oxidizing reagents these stack sheets of graphite exfoliated to be graphite oxide. The carbon atoms plane in graphite oxide is heavily decorated by oxygen-containing groups, which expand the interlayer distance and make the atomic-thick lay- ers hydrophilic [18]. These oxidized layers can be exfoliated in water under moderate ultrasonication. Reduction of graphene oxide sheets using reduc- tive reagents such as sodium borohydride [19, 20] removes the oxygen-containing groups to produce