Vol.:(0123456789) 1 3 Graphene Technology https://doi.org/10.1007/s41127-020-00030-4 ORIGINAL ARTICLE Reducing graphene oxide using hydroiodic acid fumes and low temperature annealing for enhanced electrical conductivity G. Shruthi 1  · G. Baishali 2  · V. Radhakrishna 3  · Payal Verma 1 Received: 26 February 2019 / Revised: 26 March 2020 / Accepted: 7 April 2020 © Springer Nature Switzerland AG 2020 Abstract In this work, a novel hybrid technique for reduction of graphene oxide is explored. The hybrid technique involves chemical reduction of graphene oxide coated over oxidized silicon substrate, by minimal exposure to HI acid fumes followed by low temperature thermal annealing under vacuum environment. Observations have shown improved conductivity as compared to other hybrid techniques and low temperature thermal annealing technique. Keywords Reduced graphene oxide · Thermal annealing · Hybrid reduction · XRD · Raman spectroscopy · SEM · Electrical conductivity 1 Introduction Recently graphene has attracted a lot of attention due to its remarkable electronic properties and its applications in various felds including electronics and optoelectronics [1–4]. Graphene is a two-dimensional sheet of carbon atoms arranged in a honeycomb lattice. It is extremely light weight, has excellent mechanical and electrical properties, which makes it a suitable candidate for portable devices. Many people have reported synthesis of graphene monolayer by Chemical Vapor Deposition (CVD) technique for diferent electronic applications [5–7]. CVD is a costly process and is difcult to synthesize for large area electronic devices. Gra- phene, when prepared by mechanical exfoliation is known to have best quality but the size of the obtained fakes and its controllability is very low [8]. Graphene can also be pre- pared by reducing graphene oxide (GO) [9–14]. This method uses chemical route and hence is cost efective with higher yield. However, reduction of graphene on large scale with controlled parameters over various kinds of substrates is a major challenge [3]. Conductivity of reduced graphene oxide (rGO) is not comparable to that of pristine graphene but can be improved by using diferent routes of reduction of  GO [9]. There are different routes to reduce GO to achieve maximum electrical conductivity [9, 10] of which thermal reduction [11] and chemical reduction [12–14] routes are widely used. It is well known that thermal reduction gives better electrical conductivity than chemical or electrochemi- cal methods [15]. In thermal reduction, GO is exposed to high temperature of around 1050 °C in a vacuum furnace or furnace flled with inert gas namely nitrogen or argon. Sometimes the furnace is flled with a mixture of two gases to avoid the burning of GO [16]. This method is useful for bulk production of rGO, but the main limitation of this method is its reduced yield and higher defect density [17]. There are literatures which shows the reduction of GO by low temperatures around 90–300 °C as well [18–21]. In this method, hydroxyl and epoxy groups are removed and restored with C=C sp 2 bonds. The chemical reduction of GO uses strong reducing agents to remove the oxygen con- taining groups from GO. Hydrazine and its derivatives like hydrazine hydrate and dimethyl hydrazine are universally accepted good chemical reagents to reduce GO [22]. Reduc- ing by this method is simple and gives good electrically conducting rGO. However, hydrazine groups tend to leave C–N group on rGO during reduction process and also it is a highly toxic reagent. Thus, development of new reduction methods of GO that are eco-friendly, low cost and feasible * G. Baishali baishaligarai-phy@dsu.edu.in 1 Department of Electronics and Communication Engineering, Dayananda Sagar University, Bangalore, India 2 Department of Physics, Dayananda Sagar University, Bangalore, India 3 Space Astronomy Group, U R Rao Satellite Centre, Bangalore, India