Soft Processing of Graphene Nanosheets by Glycine-Bisulfate Ionic-Complex-Assisted Electrochemical Exfoliation of Graphite for Reduction Catalysis

摘要

This study demonstrates a mild, environmentally friendly, and cost-effective soft processing approach for the continuous synthesis of high-quality, few-layer graphene nanosheets. This has been achieved via electrochemical exfoliation of graphite, using an environmentally friendly glycine-bisulfate ionic complex and was performed under ambient reaction conditions. Graphene nanosheets with 2-5 layers were obtained under optimized exfoliation conditions using a 15 wt% glycine-bisulfate (aqueous) solution, with working biases of+1 V and +3 V applied for 5 min. The role of the glycine-bisulfate ionic complex in the electrochemical exfoliation process was confirmed through comparison with a control experiment using only sulfuric acid as the electrolyte. A plausible electrochemical exfoliation mechanism that involves the formation of surface molecule nuclei via the polymerization of intercalated monomeric HSO_4~- and SO_4~(2-) ions is proposed. The ionic complex plays a key role in the anodic graphite exfoliation via electrochemical-potential-induced intercalation, leading to an efficient expansion of graphite sheets via the insertion of oxygen functional groups.