Graphene-based macroscopic assemblies and architectures: an emerging material system

Controlling the shell formation in hydrothermally reduced graphene hydrogel

Graphene hydrogels/aerogels are emerging three-dimensional graphene macroscopic assemblies of potential use in many applications including energy storage, pollutant adsorption, and gas sensing. In this Letter, we identify, characterize and control the formation of the exterior shell structure of graphene hydrogels prepared via hydrothermal reduction of graphene oxide. Unlike the porous bulk of the hydrogel, the shell is a compact, highly ordered layer with a higher electrical conductivity. Shell formation is dependent upon the surface anchoring of graphene oxide at the liquid-air and liquid-container interfaces. By purposefully weakening surface anchoring of graphene oxide using mild thermal or chemical prereduction method prior to hydrothermal reduction, we have succeeded in completely suppressing shell formation in the graphene hydrogel. The resulting graphene hydrogel shows a lower volume reduction with a porous bulk structure immediately accessible from the surface, in contrast to graphene hydrogels prepared under conventional conditions.

Graphene foam developed with a novel two-step technique for low and high strains and pressure-sensing applications

Freestanding, mechanically stable, and highly electrically conductive graphene foam (GF) is formed with a two-step facile, adaptable, and scalable technique. This work also demonstrates the formation of graphene foam with tunable densities and its use as strain/pressure sensor for both high and low strains and pressures.

A general method of fabricating flexible spinel-type oxide/reduced graphene oxide nanocomposite aerogels as advanced anodes for lithium-ion batteries

High-capacity anode materials for lithium ion batteries (LIBs), such as spinel-type metal oxides, generally suffer from poor Li(+) and e(-) conductivities. Their drastic crystal structure and volume changes, as a result of the conversion reaction mechanism with Li, severely impede the high-rate and cyclability performance toward their practical application. In this article, we present a general and facile approach to fabricate flexible spinel-type oxide/reduced graphene oxide (rGO) composite aerogels as binder-free anodes where the spinel nanoparticles (NPs) are integrated in an interconnected rGO network. Benefiting from the hierarchical porosity, conductive network and mechanical stability constructed by interpenetrated rGO layers, and from the pillar effect of NPs in between rGO sheets, the hybrid system synergistically enhances the intrinsic properties of each component, yet is robust and flexible. Consequently, the spinel/rGO composite aerogels demonstrate greatly enhanced rate capability and long-term stability without obvious capacity fading for 1000 cycles at high rates of up to 4.5 A g(-1) in the case of CoFe2O4. This electrode design can successfully be applied to several other spinel ferrites such as MnFe2O4, Fe3O4, NiFe2O4 or Co3O4, all of which lead to excellent electrochemical performances.

From supramolecular hydrogels to functional aerogels: a facile strategy to fabricate Fe3O4/N-doped graphene composites

The Fe₃O₄/N-GAs directly derived from Fc-F/GO supramolecular hydrogels act as multifunctional reagents, including Fe/N sources and the dispersant of GO.

Synthesis of conjugated covalent organic frameworks/graphene composite for supercapacitor electrodes

A novel imine-linked covalent organic framework on graphene composite with excellent electrochemical properties was conveniently synthesized in one step.

Sorption of radionuclides from aqueous systems onto graphene oxide-based materials: a review

Graphene oxide-based nanomaterials are suitable materials for the preconcentration of radionuclides and heavy metal ions from aqueous solutions in environmental pollution cleanup.

Environmental applications of graphene-based nanomaterials

A critical assessment of recent developments in environmental applications of graphene and graphene-based materials.

Graphene oxide as a template for a complex functional oxide

Graphene oxide monoliths of defined macromorphology are used to direct the structure of complex oxides for improved functionality.

Stability of graphene-based heterojunction solar cells

The long-term environmental stability and degradation of graphene-based heterojunction solar cells under different atmospheric conditions such as air, humidity, temperature, and light illumination for commercial applications are discussed.

Multiple roles of graphene in heterogeneous catalysis

This review provides a brief but comprehensive understanding of the different roles of graphene in heterogeneous catalysis, i.e., its use as a catalyst support and its intrinsic catalytic properties originating from the defects and heteroatom-containing functionalities.

High quality sub-10 nm graphene nanoribbons by on-chip PS-b-PDMS block copolymer lithography

“High quality sub-10 nm graphene nanoribbons by on-chip PS-b-PDMS block copolymer lithography”, SEM image of sub-10 nm graphene nanoribbons fabricated using a brushless lamellar PS-b-PDMS (5k–5.5k) block copolymer and its Raman spectra.

Structural design of graphene for use in electrochemical energy storage devices

This review elucidates the structural design methodologies toward high-performance graphene-based electrode materials for electrochemical energy storage devices.

Graphene-based materials for flexible supercapacitors

The recent advances in developing graphene-based materials for flexible supercapacitors are summarized in this review.