No abstract

Eco‐friendly, electrochemically active electrode materials based on covalent graphene derivatives offer enormous potential for energy storage applications. However, covalent grafting of functional groups onto the graphene surface is challenging due to its low reactivity. Here, fluorographene chemistry was employed to graft an arginine moiety via its guanidine group homogeneously on both sides of graphene. By tuning the reaction conditions and adding a non‐toxic pore‐forming agent, an optimum degree of functionalization and hierarchical porosity was achieved in the material. This tripled the specific surface area and yielded a high capacitance value of approximately 390 F g−1 at a current density of 0.25 A g−1. The applicability of the electrode material was investigated under typical operating conditions by testing an assembled supercapacitor device for up to 30000 charging/discharging cycles, revealing capacitance retention of 82.3 %. This work enables the preparation of graphene derivatives with covalently grafted amino acids for technologically important applications, such as supercapacitor‐based energy storage.

Fluorographene, at wo-dimensional derivativeo f graphene, is an excellent starting materialf or the synthesis of graphene derivatives. In this work, ao ne-step, substratefree method for the asymmetricf unctionalization of fluorographene layers with hydroxyl groups by af acile nucleophilic substitution reactioni sr eported. Such ac hemical modification occurs in ab iphasic aqueous-organic system under mild conditions, leading to Janus graphene nanosheets functionalized by hydroxyl groups on one side and retaining fluorine atoms on the other.T he reported experimental route paves the way for two-dimensional bifacial graphene templates, thus broadening the application potential of graphene materials.

Oxygen-containing functional groups in graphene oxide are potent cell adhesion enhancers.