Green Solid-State Chemical Reduction of Graphene Oxide Supported on a Paper Substrate

Abstract

The reduction of graphene oxide (GO) thin films deposited on substrates is crucial to achieve a technologically useful supported graphene material. However, the well-known thermal reduction process cannot be used with thermally unstable substrates (e.g., plastics and paper), in addition photo-reduction methods are expensive and only capable of reducing the external surface. Therefore, solid-state chemical reduction techniques could become a convenient approach for the full thickness reduction of the GO layers supported on thermally unstable substrates. Here, a novel experimental procedure for quantitative reduction of GO films on paper by a green and low-cost chemical reductant (L-ascorbic acid, L-aa) is proposed. The possibility to have an effective mass transport of the reductant inside the swelled GO solid (gel-phase) deposit was ensured by spraying a reductant solution on the GO film and allowing it to reflux in a closed microenvironment at 50 °C. The GO conversion degree to reduced graphene oxide (r-GO) was evaluated by Fourier transform infrared spectroscopy (FT-IR) in attenuated total reflectance (ATR) mode and X-ray Diffraction (XRD). In addition, morphology and wettability of GO deposits, before and after reduction, were confirmed by digital USB microscopy, scanning electron microscopy (SEM), and contact angle measurements. According to these structural characterizations, the proposed method allows a bulky reduction of the coating but leaves to a GO layer at the interface, that is essential for a good coating-substrate adhesion and this special characteristic is useful for industrial exploitation of the material.

Green Carbon Nanostructures for Functional Composite Materials

“…In the last few years, many innovative reduction strategies have been reported. The main approaches to reduce GO are chemical reduction [26], thermal decomposition [19], or strategies involving a combination of thermal and chemical methods [20]. Electrochemical reduction is another eco-friendly methodology, where GO is reduced in a standard electrochemical cell through the application of voltage.…”

Gel-Phase Reduction of Graphene Oxide Coatings by L-Ascorbic Acid

“…Such treatment lasted for ca. 48 h. More details about developed procedure can be found in Longo et al [14]. To improve the diffusion of reductant agent into thin coating of GO, the system was closed in a suitable petri dish and was heated at a low temperature (50 °C) by using a controlled hot plate.…”

“…Inspired by the growing concerns regarding environmental pollution, a novel experimental procedure for quantitative reduction of GO films on paper by a green and low-cost chemical reductant (L-ascorbic acid, L-aa) was proposed in our previous work [14]. L-aa is much more environmentally friendly then typical GO reductants like hydrazine and hydrazine hydrate [15][16][17].…”