This paper gives a comprehensive review about the most recent progress in synthesis, characterization, fundamental understanding, and the performance of graphene and graphene oxide sponges. Practical applications are considered including use in composite materials, as the electrode materials for electrochemical sensors, as absorbers for both gases and liquids, and as electrode materials for devices involved in electrochemical energy storage and conversion. Several advantages of both graphene and graphene oxide sponges such as three dimensional graphene networks, high surface area, high electro/ thermo conductivities, high chemical/electrochemical stability, high flexibility and elasticity, and extremely high surface hydrophobicity are emphasized. To facilitate further research and development, the technical challenges are discussed, and several future research directions are also suggested in this paper. Broader contextAdvanced graphene materials residing at the frontier of scientic research offer immense potential for overcoming the challenges related to the performance, functionality and durability of key functional materials' in the elds of life science, energy, and the environment. Future demand necessitates advanced processing methods be developed that can mass produce high quality, two-dimensional graphene sheets while overcoming the issues of poor dispersion and restacking with large size-scale deployment of two-dimensional graphene sheets. These issues, along with graphene sheet defects and multilayer thicknesses prevent the full realization of graphene's high potential, including electronic properties and high surface area. Three-dimensional arrangements have been recently able to address these limitations, by creating sponge-like low density materials with a long list of benecial properties including: macroscale size, high accessible surface area, less restacking, highly-interconnected microstructure, high strength and exibility, fast ion transport and electron conductivity. This review is intended to address the continued developments and challenges with a wide scope of interest, highlighting fundamental understanding of the synthesis and characterization procedures, future outlook, as well as an in-depth discussion of application areas reporting high performance in recent publications. The outstanding potential of these materials has enabled signicant enhancements for numerous important applications such as electrochemical energy storage and conversion, absorption, sensing, catalysis, transistors and polymer composites.

The unique TiO2-C/MnO2 core-double-shell nanowires are synthesized for the first time using as anode materials for lithium ion batteries (LIBs). They combine both advantages from TiO2 such as excellent cycle stability and MnO2 with high capacity (1230 mA h g(-1)). The additional C interlayer intends to improve the electrical conductivity. The self-supported nanowire arrays grown directly on current-collecting substrates greatly simplify the fabrication processing of electrodes without applying binder and conductive additives. Each nanowire is anchored to the current collector, leading to fast charge transfer. The unique one-dimensional core-double-shell nanowires exhibit enhanced electrochemical performance with a higher discharge/charge capacity, superior rate capability, and longer cycling lifetime.

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Exploiting the emulsification properties of low cost, environmentally safe Gum Arabic we demonstrate a high yield process to produce a few layer graphene with a low defect ratio, maintaining the pristine graphite structure. In addition, we demonstrate the need for and efficacy of an acid hydrolysis treatment to remove the polymer residues to produce 100% pure graphene. The scalable process gives yield of up to 5 wt% graphene based on 10 g starting graphite. The graphene product is compared with reduced graphene oxide produced through Hummer's method using UV-visible spectroscopy, SEM, TEM, and Raman spectroscopy. The two graphene materials show significant difference in these characterizations. Further, the film fabricated from this graphene exhibits 20 times higher electrical conductivity than that of the reduced graphene oxide. Sonication processing of graphite with environmentally approved biopolymers such as Gum Arabic opens up a scalable avenue for production of cheap graphene.

This study reports the preparation of pyrrolic-structure enriched nitrogen doped graphene by hydrothermal synthesis at varied temperature. The morphology, structure and composition of the prepared nitrogen doped graphene were confirmed with SEM, XRD, XPS and Raman spectroscopy. The material was tested for supercapacitive behavior. It was found that doping graphene with nitrogen increased the electrical double layer supercapacitance to as high as 194 F g À1 . Furthermore, density functional theory (DFT) calculations showed the proper level of binding energy found between the pyrrolic-nitrogen structure and the electrolyte ions, which may be used to explain the highest contribution of the pyrrolic-structure to the capacitance. Experimental Synthesis of graphitic oxideThe graphite oxide (GO) was prepared following the modied Hummers' method in which graphite akes are oxidized using a