Owing to its high surface area and excellent conductivity, graphene is considered an efficient electrode material for supercapacitors. However, its restacking in electrolytes hampers its broader utilization in this field. Covalent graphene functionalization is a promising strategy for providing more efficient electrode materials. The chemistry of fluorographene is particularly attractive as it allows scalable chemical production of useful graphene derivatives. Nevertheless, the influence of chemical composition on the capacitance of graphene derivatives is a largely unexplored field in nanomaterials science, limiting further development of efficient graphene-based electrode materials. In the present study, we obtained well-defined graphene derivatives differing in chemical composition but with similar morphologies by controlling the reaction time of 5-aminoisophthalic acid with fluorographene. The gravimetric specific capacitance ranged from 271 to 391 F g –1 (in 1 M Na 2 SO 4 ), with the maximum value achieved by a delicate balance between the amount of covalently grafted functional groups and density of the sp 2 carbon network governing the conductivity of the material. Molecular dynamics simulations showed that covalent grafting of functional groups with charged and ionophilic/hydrophilic character significantly enhanced the ionic concentration and hydration due to favorable electrostatic interactions among the charged centers and ions/water molecules. Therefore, conductive and hydrophilic graphitic surfaces are important features of graphene-based supercapacitor electrode materials. These findings provide important insights into the role of chemical composition on capacitance and pave the way toward designing more efficient graphene-based supercapacitor electrode materials.

Supercapacitors are a promising energy storage technology owing to their unparalleled power and lifetime. However, to meet the continuously rising demands of energy storage, they must be equipped with higher energy densities. For this purpose, the seamless integration of metal oxides on carbon matrices, such as iron oxides/oxyhydroxides, has been pursued through hydrothermal, atomic layer and electro-deposition methods directly on current collectors. Nevertheless, such methods present limited compatibility with commercial paste-coating processes on the current collectors. Furthermore, iron oxides/oxyhydroxides lack conductivity and are hydrophilic, operating with low-voltage aqueous electrolytes, limiting their power and energy and requiring corrosion-resistant H 2 O current collectors. To mitigate these challenges, a seamless and paste-ready material is successfully developed through a 15 min wet-chemical method, via the coordination of ultrasmall β-FeOOH (akaganéite) nanoparticles to the nitrile groups of a covalent graphene derivative. Endowed with graphene-like impedance response and very high wettability in organic electrolytes, combined high power and energy densities are obtained, with respect to the total mass of both electrode materials and current collectors, overcoming the identified challenges. This offers future prospects for the exploration of alternative molecular handles for improved interfaces and their application in different energy-storage chemistries.

In hypergolics two substances ignite spontaneously upon contact without external aid. Although the concept mostly applies to rocket fuels and propellants, it is only recently that hypergolics has been recognized from our group as a radically new methodology towards carbon materials synthesis. Comparatively to other preparative methods, hypergolics allows the rapid and spontaneous formation of carbon at ambient conditions in an exothermic manner (e.g., the method releases both carbon and energy at room temperature and atmospheric pressure). In an effort to further build upon the idea of hypergolic synthesis, herein we exploit a classic liquid rocket bipropellant composed of furfuryl alcohol and fuming nitric acid to prepare carbon nanosheets by simply mixing the two reagents at ambient conditions. Furfuryl alcohol served as the carbon source while fuming nitric acid as a strong oxidizer. On ignition the temperature is raised high enough to induce carbonization in a sort of in-situ pyrolytic process. Simultaneously, the released energy was directly converted into useful work, such as heating a liquid to boiling or placing Crookes radiometer into motion. Apart from its value as a new synthesis approach in materials science, carbon from rocket fuel additionally provides a practical way in processing rocket fuel waste or disposed rocket fuels.