Thiourea Dioxide as a Green Reductant for the Mass Production of Solution-Based Graphene

Abstract

Mass production of solution-based graphene derived from the precursor graphene oxide is a challenging step toward achieving industrialization of graphene. Inspired by a classical reducing method performed in the textile and paper making industries, we report here a rapid, cost-effective and safer approach to the facile production of graphene that employs thiourea dioxide (TDO) as the green reductant. Graphene oxide was converted into high quality graphene within 30 minutes with TDO as the reductant under moderate reaction conditions. The C/O ratio of the TDO reduced graphene was ~5.9 with the yield of graphene from graphene oxide > 99%. This is better than the reduction efficiency under the identical experimental conditions by using L-ascorbic acid as the reductant which required a reaction time of about 48 hours. This simple and effective procedure should offer an alternative route to the mass production of solution-based graphene for practical applications.

Mechanism Involving Hydrogen Sulfite Ions, Chlorite Ions, and Hypochlorous Acid as Key Intermediates of the Autocatalytic Chlorine Dioxide–Thiourea Dioxide Reaction

“…Owing to the formation of SO 2 H -/SO 2 2-ions from the rapid decomposition of TDO in alkaline solutions, [5,6] TDO has been extensively applied in chemistry and chemical technology as a special and effective reducing agent, [7][8][9][10] especially for the potential chemical reduction of graphene oxide in recent years. [11,12] Its reducing ability increases with aging in alkaline solution. The stability of sulfoxylate ions increases with increasing pH under anaerobic conditions.…”

Recent Developments in the Chemistry of Thiourea Oxides

“…Even within this long list, thiourea dioxide (TDO) occupies a special place, especially as its versatile properties extend distinctly beyond those of a simple reducing agent. While TDO has long been used in chemistry and chemical technology,2 in the last 15–20 years traditional as well as new fields of its application have been developed, both theoretical and practical aspects, such as reduction of graphene3a–f and graphite oxides;3g synthesis of metal sulfides4a and preparation of nanometer metal powders;4b organic synthesis5 including organocatalytic,6 phase‐transfer7 and polymerization reactions;8 bitumen modifications;9 and the study of nonlinear dynamical phenomena in chemical kinetics 10a–c. Derivatives of TDO, such as N , N ′‐dimethylthiourea dioxide have also been successfully applied in the latter field 10d.…”

Preparation of Graphene from Graphene oxide by Chemical Reducing Agents

“…Fugestu and co-workers 59 suggested a comparable reduction ability of thiourea in an alkaline (NaOH) medium. Sodium chlorate was used as a stabilizer to maintain the high stability in an aqueous solution of graphene and showed a 5.89 C/O ratio and conductivity 3205 Sm -1 .…”