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Growth of Reduced Graphene Oxide Jingfeng Huang1,2,3, Hu Chen1,2,3, Derrick Fam1, Steve H. Faulkner3, Wenbin Niu1, Melanie Larisika4,5, Christoph Nowak4,5, Myra A. Nimmo2,3 and Alfred Iing Yoong Tok1,2* 1

School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore. Tel.: +65 67904935. E-mail address: [email protected]. 2 Institute for Sports Research, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore. 3 School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE113TU, UK. 4 Austrian Institute of Technology (AIT) GmbH, Donau-City Str.1, Vienna, 1220, Austria. 5 Centre for Biomimetic Sensor Science, 50 Nanyang Drive, Singapore, 637553, Singapore. ABSTRACT Reduced graphene oxide (RGO) has the advantage of an aqueous and industrial-scalable production route. However, one of the main limitations that prevent the use of RGO in electronics is the high electrical resistance deviation between fabricated chips. In this article, we present the novel growth of RGO which can bridge the gaps in-between existing flakes and thus reduce the electrical resistance standard deviation from 80.5 % to 16.5 %. The average resistivity of the treated RGO of ~ 3.8 nm thickness was 200 Ω/square. The study uses an atmosphericpressure chemical vapour deposition (CVD) system with hydrogen and argon gas bubbling through ethanol before entering the furnace. With a treatment of 2 hours, 100 % of the silicon dioxide substrate was covered with RGO from an initial 65 % coverage. This technology could enable large-scale application of RGO use in practical electronic devices. INTRODUCTION Reduced graphene oxide (RGO) or chemically derived graphene (CDG) can be used as an alternative to graphene in electronics because it has a tunable band gap and that it has the advantage of a scalable and solution processable route[1-4]. However, current RGO devices have high variation in the electrical resistivity because the varying coverage of RGO flakes that can range from 60-90%. For this reason, 100% coverage like CVD grown graphene[5-8] is necessary. In this paper, we report a post-treatment process to graphene oxide (GO) to simultaneously reduce, grow it and extend the coverage to 100% in 2 hours. To grow graphene, a catalyst such as copper[5] or nickel[9] is needed. The high carbon solubility of nickel film allows the diffusion of carbon into the film at growth temperature and precipitate out of the substrate upon cooling; whereas the low carbon solubility of copper catalytically decomposes alcohol into radicals and allows adsorption of the carbon on the surface[6]. Recently, the extended growth of carbon nanotube without any additional catalyst has been reported[10]. The extended growth followed the configuration and structure of the original nanotube template. A convincing model is still lacking on how the carbon is nucleated and

grown from this template. There had been reports of using ethanol CVD to repair both graphene and GO[11, 12]; but no growth was observed. Her