Nylon/Graphene Oxide Electrospun Composite Coating

Graphite oxide is obtained by treating graphite with strong oxidizers. The bulk material disperses in basic solutions yielding graphene oxide. Starting from exfoliated graphite, different treatments were tested to obtain the best graphite oxide conditions, including calcination for two hours at 700°C and ultrasonic agitation in acidic, basic, or peroxide solutions. Bulk particles floating in the solution were filtered, rinsed, and dried. The graphene oxide obtained was characterized under SEM and FTIR techniques. On the other hand, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of its long chains. To take advantage of the properties of both materials, they were combined as a hybrid material. Electrochemical cells were prepared using porous silica as supporting electrode of the electrospun nylon/graphene oxide films for electrochemical testing. Polarization curves were performed to determine the oxidation/reduction potentials under different acidic, alkaline, and peroxide solutions. The oxidation condition was obtained in KOH and the reduction in H2SO4 solutions. Potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then reduced them, forming the nylon 6-6/functionalized graphene oxide composite coating. Electrochemical impedance measurements were performed to evaluate the coating electrochemical resistance and compared to the silica or nylon samples. 1. Introduction Graphite oxide is a compound of carbon, oxygen, and hydrogen in variable ratios, commonly obtained by treating graphite with strong oxidizers. Strictly speaking “oxide” is an incorrect but historically established name, since graphite is not a metal. The bulk material disperses in basic solutions yielding monomolecular sheets, known as graphene oxide by analogy to graphene, the single-layer form of graphite [1]. Graphene oxide (GO) sheets have recently attracted substantial interest as a possible intermediate for the manufacture of graphene. It typically preserves the layer structure of the parent graphite, but the layers are buckled and the interlayer spacing is about two times larger (~0.7？nm) than that of graphite. Graphene oxide layers are about ？nm thick [2–6]. The edges of each layer are terminated with carboxyl and carbonyl groups. The detailed structure is still not understood due to the strong disorder and irregular packing of the layers [1]. One of the methods used to separate the layers of graphite consists in an aggressive oxidative processes which functionalize the periphery and some places of the graphene