A super-flexible high thermal conductive graphene film and a preparation method thereof are provided. The graphene film is obtained from ultra large homogeneous graphene sheets through processes of solution film-forming, chemical reduction, high temperature reduction, high pressure suppression and so on. The graphene film has a density in a range of 1.93 to 2.11 g/cm.sup.3, is formed by overlapping planar oriented graphene sheets with an average size of more than 100 μm with each other through π-π conjugate action, and comprises 1 to 4 layers of graphene sheets which have few defects. The graphene film can be repeatedly bent for 1200 times or more, with elongation at break of 12-18%, electric conductivity of 8000-10600 S/cm, thermal conductivity of 1800-2600 W/mK, and can be used as a highly flexible thermal conductive device.

Disclosed is AA′ graphite with a new stacking feature of graphene, and a fabrication method thereof. Graphene is stacked in the sequence of AA′ where alternate graphene layers exhibiting the AA′ stacking are translated by a half hexagon (1.23 Å). AA′ graphite has an interplanar spacing of about 3.44 Å larger than that of the conventional AB stacked graphite (3.35 Å) that has been known as the only crystal of pure graphite. This may allow the AA′ stacked graphite to have unique physical and chemical characteristics.

In the graphene manufacturing method, a graphite oxide is formed from graphite, and then the graphite oxide is treated with a hydrochloric acid. The hydrochloric acid-treated graphite oxide is reduced at temperature of 120° C. or above and 200° C. or below by performing thermal treatment thereto. Since a low-temperature process is used for manufacturing graphene by performing thermal treatment at a relatively low temperature for a short time, this method has great economic feasibility and utilization. Due to a simple composing process and low thermal treatment temperature, graphene may be mass-produced with a low price. In particular, the graphene may be used as a cathode material for a lithium secondary battery, which exhibits a high capacity at a high voltage of 2V or above by reacting with Li, different from an anode material of a lithium secondary battery.

A method for preparing large graphene sheets in large scale includes steps of: under a mild condition, processing graphite powders with intercalation through an acid and an oxidant; washing away metal ions and inorganic ions in the graphite powders with dilute hydrochloric acid, then filtering and drying; and, finally processing with a heat treatment. The present invention breaks through a series of bottlenecks restricting an efficient preparation of graphene that result from a traditional method of using large amounts of deionized water to wash graphite oxide to be neutral, and easily realizes a batch production. A radial scale of the prepared graphene sheets is distributed from 20 um to 200 um.

A battery-powered analyte sensing system includes a printed battery and an analyte sensor. The printed battery includes an anode composed of a non-toxic biocompatible metal, a first carbon-based current collector in electrical contact with the anode, a three-dimensional hierarchical mesoporous carbon-based cathode, a second carbon-based current collector, and an electrolyte layer disposed between the anode and the cathode, the electrolyte layer configured to activate the printed battery when the electrolyte is released into one or both the anode and the cathode. The analyte sensor includes a sensing material and a reactive chemistry additive in the sensing material.

The invention provides a method of producing graphene. The method comprising: A) mixing graphite powders with a silk fibroin nanofiber solution, performing mechanical stirring to exfoliate graphite to form graphene flakes; wherein the silk fibroin nanofibers in the silk fibroin nanofiber solution have a crystallinity of 40% or above; the silk fibroin nanofibers have a diameter of 10 to 30 nm; the silk fibroin nanofibers have a length of 100 nm to 3 μm; the mechanical stirring has a shearing speed of 1,000 to 50,000 rpm; and the duration of the mechanical stirring is 10 min to 6 h; B) centrifuging the solution obtained in step A) after exfoliation to remove unexfoliated graphite; and C) centrifuging the centrifuged solution obtained in step B), and separating graphene from the silk fibroin nanofibers to obtain the graphene.

Disclosed is a graphene electrochemical transfer method assisted by multiple supporting films, comprising: (1) growing graphene on a substrate, and then spin-coating a thin layer of photoresist on a surface of the graphene as a first film; (2) spin-coating n layers of thick, tough, and selectively dissolvable polymer films on the surface of the first film as an top film; (3) dissociating the multi-layer composite film and the graphene from the surface of the substrate by an electrochemical process, and dissolving the thick polymer films which is the top film with a first solvent; (4) after cleaning, transferring the thin first film and the graphene to a target substrate, and finally dissolving the thin first film away with a second solvent to complete the transfer process. This transfer process is fast, stable, and capable of transferring a large-size graphene, which may promote the large-scale application of graphene.

Methods for growing microstructured and nanostructured graphene by growing the microstructured and nanostructured graphene from the bottom-up directly in the desired pattern are provided. The graphene structures can be grown via chemical vapor deposition (CVD) on substrates that are partially covered by a patterned graphene growth barrier which guides the growth of the graphene.

The first present invention is a graphite sheet having a thickness of not more than 9.6 μm and more than 50 nm and a thermal conductivity along the a-b plane direction at 25° C. of 1950 W/mK or more. The second present invention is a graphite sheet having a thickness in a range of less than 9.6 μm and 20 nm or more, an area of 9 mm2 or more, and a carrier mobility along the a-b plane direction at 25° C. of 8000 cm2/V.Math.sec or more.

Compositions comprising hydrogenated and dehydrogenated graphite comprising a plurality of flakes. At least one flake in ten has a size in excess of ten square micrometers. For example, the flakes can have an average thickness of 10 atomic layers or less.