Baocheng Yang

Ultrafast growth of carbon nanotubes on graphene for capacitive energy storage.

We have demonstrated a novel three-dimensional (3D) architecture of a graphene/carbon nanotube (G-CNT) hybrid synthesized at large scale within just 5 s via a simple microwave-heating method without the usage of any other conducting or expanding agent for the first time. The carbon composites obtained consist of evenly grown CNTs with an average diameter of about 15 nm on the surface of graphene nanosheets. The G-CNT hybrid exhibits enhanced electrochemical performance for both aqueous and organic supercapacitor devices. Particularly, the G-CNT electrodes demonstrate an enhanced specific capacitance of 361 F g(-1) at a current density of 1.1 A g(-1) in an aqueous electrolyte and a volumetric capacitance of 254 F cm(-3) in an organic electrolyte. They also display excellent cycle stability with nearly 91.2% of the initial capacitance retained after 10 000 charging-discharging cycles at a current density of 15 A g(-1). This demonstrates that the developed composites have potential applications in supercapacitors and other energy storage devices.

Freestanding polyaniline nanorods grown on graphene for highly capacitive energy storage

Freestanding polyaniline (PANI) nanorods grown in situ on microwave-expanded graphene oxide (MEGO) sheets were prepared through a facile solution method. The morphological characterization indicates that large quantity of free-standing PANI nanorods with average diameter of 50 nm were uniformly deposited onto the double sides of the MEGO nanosheets to form a sandwich structure. The hybrid of PANI/MEGO (GPANI) exhibit high specific surface area and high electrical conductivity, compared with pristine PANI nanorods. When evaluated as electrodes for supercapacitors, the GPANI demonstrate high specific capacitance of 628 F g(-1) at a current density of 1.1 A g(-1), high-rate performance, and excellent cycle stability compared to individual component. Such excellent electrochemical performance should be attributed to the combined double-layer capacitance and pseudo -capacitance mechanisms from the MEGO sheets and PANI nanorods.

Freestanding 3D mesoporous graphene oxide for high performance energy storage applications

We report a novel thermal reduction process to obtain freestanding 3D mesoporous graphene with excellent electrical conductivity for supercapacitor electrode applications in the presence of a CO atmosphere. The introduction of CO can not only effectively reduce and repair graphene oxide (GO) with fewer defects, but also activate graphene with highly mesoporous nanostructures. The CO-activated thermal graphene oxide (CRGO) exhibits enhanced specific capacitance of 291 Fg−1 at a current density of 1 Ag−1, high rate capability, and excellent cycle performance compared to conventional thermal reduced GO. The method demonstrated that the help of CO is an efficient method for the improvement of the supercapacitive performance of thermally reduced graphene oxide.