Anran Liu

Bio: Anran Liu is an academic researcher from Tsinghua University. The author has contributed to research in topics: Graphene & Medicine. The author has an hindex of 8, co-authored 8 publications receiving 2864 citations.

Supercapacitors Based on Flexible Graphene/Polyaniline Nanofiber Composite Films

Abstract: Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 × 102 S m−1) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g−1) at a discharge rate of 0.3 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

High‐Performance NO2 Sensors Based on Chemically Modified Graphene

Abstract: Covalently grafting reduced graphene oxide (rGO) sheets with sulfophenyl or ethylenediamine groups can produce chemically modified graphene (CMG) for fabricating high-performance gas sensors. The NO(2) sensors based on these CMGs exhibit sensitivities 4 to 16 times higher than that of a sensor based on rGO. They also show excellent selectivity and repeatability without the aid of UV-light or thermal treatment.

Electrochemical Deposition of Polypyrrole/Sulfonated Graphene Composite Films

Abstract: Composite films of sulfonated graphene (SG) and polypyrrole (PPy) were electrochemically deposited from the aqueous solutions containing pyrrole monomer, SG sheets, and dodecylbenzene sulfonic acid (DBSA). During the process of electrochemical polymerization, negatively charged SG sheets acted as a dopant of PPy. Thus, they were uniformly dispersed in the PPy matrices of resulting composites. The introduction of SG sheets improved the conductivity and electrochemical properties of PPy films. The composite films containing about 40% (by weight) SG showed a high specific capacitance of 285 F g−1 at a discharge rate of 0.5 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

Electrically conductive and mechanically strong biomimetic chitosan/reduced graphene oxide composite films

Abstract: Composite films of chitosan and reduced graphene oxide (RGO) sheets with nacre-like layered structure have been prepared by vacuum filtration of the stable aqueous mixture of both components. The film containing 6 wt% RGO is electrically conductive with a conductivity of 1.2 S m−1. Furthermore, it is mechanically strong and ductile; its Young's modulus, tensile strength and elongation at break were measured to be 6.3 ± 0.2 GPa, 206 ± 6 MPa and 6.5 ± 0.6%, respectively. These values partly exceed those of nacre. The high mechanical and electrical properties of chitosan/RGO composite films are mainly attributed to the uniform dispersion of RGO nanofillers in the polymer matrices to form a compact layered structure.

Electrosynthesis of graphene oxide/polypyrene composite films and their applications for sensing organic vapors

Abstract: Graphene oxide/polypyrene (GO/PPr) composite films were prepared by electrochemical co-deposition of GO and PPr from the organic electrolyte of propylene carbonate (PC). The effects of the GO content in the electrolyte and the deposition charge density on the formation of GO/PPr composite films were studied. Blending with GO improved the mechanical properties of the powdery PPr and gave the composite a continuous and porous morphology with an uninterrupted conducting phase. A chemoresistor-type vapor sensor based on the GO/PPr composite film demonstrated a fast, linear and reversible response to toluene with a high normalized sensitivity of 9.87 × 10−4 ppm−1. The mechanism of sensing the organic vapors with the GO/PPr composite film was also discussed.

Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

Graphene-based composites

Abstract: Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

Self-Assembled Graphene Hydrogel via a One-Step Hydrothermal Process

Abstract: Self-assembly of two-dimensional graphene sheets is an important strategy for producing macroscopic graphene architectures for practical applications, such as thin films and layered paperlike materials. However, construction of graphene self-assembled macrostructures with three-dimensional networks has never been realized. In this paper, we prepared a self-assembled graphene hydrogel (SGH) via a convenient one-step hydrothermal method. The SGH is electrically conductive, mechanically strong, and thermally stable and exhibits a high specific capacitance. The high-performance SGH with inherent biocompatibility of carbon materials is attractive in the fields of biotechnology and electrochemistry, such as drug-delivery, tissue scaffolds, bionic nanocomposites, and supercapacitors.

Graphene-based supercapacitor with an ultrahigh energy density

Abstract: A supercapacitor with graphene-based electrodes was found to exhibit a specific energy density of 85.6 Wh/kg at room temperature and 136 Wh/kg at 80 °C (all based on the total electrode weight), measured at a current density of 1 A/g. These energy density values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face. The curved morphology enables the formation of mesopores accessible to and wettable by environmentally benign ionic liquids capable of operating at a voltage >4 V.