Department of Chemistry , University of California , Berkeley , California 94720 , United States.
Nano Lett. 2020 Jan 8;20(1):534-539. doi: 10.1021/acs.nanolett.9b04267. Epub 2019 Dec 9.
The inertness of the graphene basal plane has notably limited its viable chemical modification pathways. We report direct azidation and subsequent click chemistry of the graphene basal plane through the electrochemical oxidation of an aqueous sodium azide solution at the graphene surface. An ∼20% nitrogen-to-carbon ratio is achieved for monolayer graphene under ambient conditions and neutral pH, and the degree of functionalization is tunable through the applied voltage. The functionalized azide groups enable both copper-catalyzed and copper-free alkyne cycloaddition click chemistry, as well as subsequent bioconjugation, and fluorescence microscopy indicates uniform functionalization across the graphene surface. Notably, we find that as the azidation, cycloaddition, and bioconjugation processes substantially shift the graphene doping level, high electrical conductivity and carrier mobility are maintained throughout the different functionalization states. By integrating the electrochemical azidation scheme with electrochemical exfoliation, we further demonstrate one-step bulk production of azidated graphene flakes from graphite. We thus open a new door to the facile preparation of diverse graphene derivatives under ambient conditions.
石墨烯基面的惰性显著限制了其可行的化学修饰途径。我们通过在石墨烯表面电化学氧化水合叠氮化钠溶液，报告了石墨烯基面的直接叠氮化和随后的点击化学。在环境条件和中性 pH 下，单层石墨烯的氮-碳比达到约 20%，并且可以通过施加的电压来调节官能化程度。功能化的叠氮基团既可以实现铜催化和无铜炔烃环加成点击化学，也可以进行后续的生物缀合，荧光显微镜表明石墨烯表面的均匀官能化。值得注意的是，我们发现随着叠氮化、环加成和生物缀合过程大大改变了石墨烯的掺杂水平，在不同的官能化状态下，高电导率和载流子迁移率得以保持。通过将电化学叠氮化方案与电化学剥落相结合，我们进一步展示了从石墨一步批量制备叠氮化石墨烯薄片。因此，我们为在环境条件下简便制备各种石墨烯衍生物开辟了新途径。
