Vitamin C Is an Ideal Substitute for Hydrazine in the Reduction of Graphene Oxide Suspensions

Abstract

The preparation of solution-processable graphene from graphite oxide typically involves a hydrazine reduction step, but the use of such a reagent in the large-scale implementation of this approach is not desirable due to its high toxicity. Here, we compare the deoxygenation efficiency of graphene oxide suspensions by different reductants (sodium borohydride, pyrogallol, and vitamin C, in addition to hydrazine), as well as by heating the suspensions under alkaline conditions. In almost all cases, the degree of reduction attainable and the subsequent restoration of relevant properties (e.g., electrical conductivity) lag significantly behind those achieved with hydrazine. Only vitamin C is found to yield highly reduced suspensions in a way comparable to those provided by hydrazine. Stable suspensions of vitamin C-reduced graphene oxide can be prepared not only in water but also in common organic solvents, such as N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP). These results open the perspective of replacing hydrazine in the reduction of graphene oxide suspensions by an innocuous and safe reductant of similar efficacy, thus facilitating the use of graphene-based materials for large-scale applications.

Impermeable barrier films and protective coatings based on reduced graphene oxide

“…Similarly, GO-polymer composites have so far exhibited gas permeability too high to consider them for realistic applications 9 . To increase the quality of GO-based coatings, it is essential to decrease the number of defects formed during the reduction process [23][24][25][26][27][28] (see Supplementary Fig. 1 and Supplementary Note 1).…”

“…The HI reduction leaves fewer structural defects and little deformation so that the mechanical strength increases, becoming even higher than that for initial GO laminates that are known to be already exceptionally strong 1 . Another interesting reducing agent is ascorbic acid, that is, vitamin C (VC) 26,28 . It shows not only good reducing characteristics but stands out as environment friendly and nontoxic, which may be a critical factor in certain applications.…”

“…It shows not only good reducing characteristics but stands out as environment friendly and nontoxic, which may be a critical factor in certain applications. Both reducing agents are believed to convert most of the functional groups attached to graphene into H 2 O, which results in little structural damage of graphene sheets during reduction [25][26][27][28][29] .…”

Artemisia herba-alba Asso eco-friendly reduced few-layered graphene oxide nanosheets: structural investigations and physical properties

“…Recently, new and more eco-friendly reducing agents for GO have been reported for the substitution of hydrazine, such as ascorbic acid (vitamin C) (66)(67)(68), alkyl amines (69)(70)(71)(72), reducing sugars (43,73), wild carrot root (74), metal nanoparticles (75,76) and powders (77,78), phytoextracts (79), green tea (80), baker's yeast (81), supercritical alcohols (82) and amino acids (67,83).…”

Influence of synthesis conditions on properties of green-reduced graphene oxide

“…Ascorbic acid (AA) has been already successfully employed as substitute for hydrazine (Zhang et al 2010). The reduced material can reach a C/O ratio of about 12.5 and a conductivity of 77 Sc m -1 (Fernandez-Merino et al 2010). Nevertheless, considering the facts that the reported rGO material still presented agglomerates in aqueous solutions and that the preservation of the unique electronic properties of rGO, and minimization of the negative impact on the structure of rGO is possible by noncovalent functionalization of rGO through p-p interactions (Bai et al 2009), the effect of PSS on the properties of rGO material was considered in this study, to offer a solution for the synthesis of stable aqueous dispersion of greenreduced GO.…”