Continuous production of nitrogen-functionalized graphene nanosheets for catalysis applications

This study reports the “continuous production” of high-quality, few-layer nitrogen-functionalized graphene nanosheets in aqueous solutions directly from graphite via a two-step method. The initial step utilizes our recently developed peroxide-mediated soft and green electrochemical exfoliation approach for the production of few-layer graphene nanosheets. The subsequent step, developed here, produces nitrogen-functionalized graphene nanosheets via selective alkylation/basic hydrolysis reactions using rather a simple nitrogen precursor bromoacetonitrile, which was never reported in the literature. A possible reaction mechanism of the nitrogen-functionalized graphene formation is proposed. The proposed method allows the quantification of the phenolic and hydroxyl functional groups of anodic few-layer graphene via the derivatization chemistry approach. Additionally, a nitrogen-functionalized graphene-gold nanocrystal hybrid is prepared using gold nanocrystals obtained via the microwave irradiation of H[AuCl₄] and trisodium citrate solution. A systematic investigation demonstrates that the nitrogen-functionalized graphene-gold nanocrystal hybrid shows enhanced catalytic reduction of carbonyl compounds such as benzaldehyde.