Qiuming Gao

Facile Approach to Prepare Nickel Cobaltite Nanowire Materials for Supercapacitors

Excellent electrochemical performance results from the coexistence of nickel and cobalt ions, with mesoporous characteristics and nanocrystal structure. Nickel cobalt nanowire is prepared by hydrothermal and thermal decomposition processes. High capacitance of 722 F g(-1) can be obtained at 1 A g(-1) in 6 M KOH, with a capacitance retention ratio of ca. 79% at 20 A g(-1) .

High hydrogen storage capacity of porous carbons prepared by using activated carbon.

A kind of activated carbon with further carbon dioxide and potassium hydroxide activations for hydrogen storage was investigated. The carbon dioxide and potassium hydroxide activations have apparently different effects on the pore structures and textures of the activated carbon which closely associated with the hydrogen storage properties. The potassium hydroxide activation can remarkably donate microporosity to the frameworks of the activated carbon. One of the resultant porous carbons exhibited a high surface area of up to 3190 m(2) g(-1) and large gravimetric hydrogen uptake capacity of 7.08 wt % at 77 K and 20 bar, which is one of the largest data reported for the porous carbon materials. This result suggests that the porous carbon with large amounts of active sites, high surface area, and high micropore volume related to optimum pore size could achieve high gravimetric hydrogen storage.

Nickel(II) Phosphate VSB‐5: A Magnetic Nanoporous Hydrogenation Catalyst with 24‐Ring Tunnels

Nanoporosity, good thermal stability, antiferromagnetic ordering, and hydrogenation with basic catalytic character are four important properties of the large-pore (24MR), zeolitic nickel(II) phosphate, VSB-5 (Ni20 [(OH)12 (H2 O)6 ][(HPO4 )8 (PO4 )4 ]⋅12 H2 O), which has been prepared under alkaline hydrothermal conditions. The structure of VSB-5 is depicted: NiO6 octahedra: green; PO4 tetrahedra: red.

Bio-inspired beehive-like hierarchical nanoporous carbon derived from bamboo-based industrial by-product as a high performance supercapacitor electrode material

Bio-inspired beehive-like hierarchical nanoporous carbon (BHNC) with a high specific surface area of 1472 m2 g−1 and a good electronic conductivity of 4.5 S cm−1 is synthesized by carbonizing the industrial waste of bamboo-based by-product. The BHNC sample exhibits remarkable electrochemical performances as a supercapacitor electrode material, such as a high specific capacitance of 301 F g−1 at 0.1 A g−1, still maintaining a value of 192 F g−1 at 100 A g−1, negligible capacitance loss after 20 000 cycles at 1 A g−1, and a high power density of 26 000 W kg−1 at an energy density of 6.1 W h kg−1 based on active electrode materials in an aqueous electrolyte system. Moreover, an enhanced power density of 42 000 W kg−1 at a high energy density of 43.3 W h kg−1 is obtained in an ionic liquid electrolyte system, which places the BHNC-based supercapacitors in the Ragone chart among the best energy–power synergetic outputting properties ever reported for carbon-based supercapacitors.

Preparing two-dimensional microporous carbon from Pistachio nutshell with high areal capacitance as supercapacitor materials

Two-dimensional (2D) porous carbon AC-SPN-3 possessing of amazing high micropore volume ratio of 83% and large surface area of about 1069 m2 g−1 is high-yield obtained by pyrolysis of natural waste Pistachio nutshells with KOH activation. The AC-SPN-3 has a curved 2D lamellar morphology with the thickness of each slice about 200 nm. The porous carbon is consists of highly interconnected uniform pores with the median pore diameter of about 0.76 nm, which could potentially improve the performance by maximizing the electrode surface area accessible to the typical electrolyte ions (such as TEA+, diameter = ~0.68 nm). Electrochemical analyses show that AC-SPN-3 has significantly large areal capacitance of 29.3/20.1 μF cm−2 and high energy density of 10/39 Wh kg−1 at power of 52/286 kW kg−1 in 6 M KOH aqueous electrolyte and 1 M TEABF4 in EC-DEC (1:1) organic electrolyte system, respectively.

Renewable graphene-like nitrogen-doped carbon nanosheets as supercapacitor electrodes with integrated high energy–power properties

The development of supercapacitors with integrated high energy–power properties coupled with long cyclic life is an urgent demand in the energy storage field. The key to the assembly of such devices is to design and fabricate novel high-performance electrode materials in conjunction with matched electrolytes. In this study, a renewable graphene-like nitrogen-doped carbon nanosheet (RGNC-NS) has been constructed by using simultaneous carbonization and auto-activation followed by ultrasonic-assisted liquid exfoliation from natural layered shrimp shells. The final RGNC-NS had an optimum integration of graphene-like nanostructures (∼5 nm thick), large specific surface area (1946 m2 g−1), and rich nitrogen doping (8.75 wt%), resulting in high conductivity (7.8 S cm−1) and good surface wettability with an electrolyte. The RGNC-NS as a supercapacitor electrode exhibited an excellent rate capability with an ultrahigh capacitance of 322 F g−1 at 0.5 A g−1 and 241 F g−1 at 100 A g−1 (75% retention), as well as a long cyclic stability of 98.3% capacitance retention after 20 000 cycles at 10 A g−1 in 6 M KOH. Moreover, the RGNC-NS in a mixed ionic liquid electrolyte displayed an integrated high energy–power density of 30 W h kg−1 energy density at 64 000 W kg−1 power density and 93.2% capacitance retention after 8000 cycles at 5 A g−1.

Biomass‐Derived Porous Carbon with Micropores and Small Mesopores for High‐Performance Lithium–Sulfur Batteries

Biomass-derived porous carbon BPC-700, incorporating micropores and small mesopores, was prepared through pyrolysis of banana peel followed by activation with KOH. A high specific BET surface area (2741 m2  g-1 ), large specific pore volume (1.23 cm3  g-1 ), and well-controlled pore size distribution (0.6-5.0 nm) were obtained and up to 65 wt % sulfur content could be loaded into the pores of the BPC-700 sample. When the resultant C/S composite, BPC-700-S65, was used as the cathode of a Li-S battery, a large initial discharge capacity (ca. 1200 mAh g-1 ) was obtained, indicating a good sulfur utilization rate. An excellent discharge capacity (590 mAh g-1 ) was also achieved for BPC-700-S65 at the high current rate of 4 C (12.72 mA cm-2 ), showing its extremely high rate capability. A reversible capacity of about 570 mAh g-1 was achieved for BPC-700-S65 after 500 cycles at 1 C (3.18 mA cm-2 ), indicating an outstanding cycling stability.

One-dimensional porous nanofibers of Co3O4 on the carbon matrix from human hair with superior lithium ion storage performance.

One-dimensional (1D) hierarchical porous nanofibers of Co3O4 possessing of (220) facets on the carbon matrix from human hair (H2@Co3O4) with 20–30 nm in width and 3–5 μm in length are prepared by a facile solvothermal and calcination approach. The well crystallized small Co3O4 particles with the diameter of about 8–12 nm were closely aggregated together in the nanofibers. Electrochemical analyses show that the first discharge capacity of H2@Co3O4 electrode is 1368 mAh g−1 at the current density of 0.1 A g−1 based on the total mass of composite. A high reversible capacity of 916 mAh g −1 was obtained over 100 cycles at 0.1 A g−1, presenting a good cycling stability. When cycled at a high current density of 1 and 2 A g−1, the specific capacity of 659 and 573 mAh g−1 could be still achieved, respectively, indicating a superior power capability.

Superlow load of nanosized MnO on a porous carbon matrix from wood fibre with superior lithium ion storage performance

A facile synthesis of an MnO/C nanocomposite material consisting of 5.3 wt% of MnO on the surface of porous carbon is introduced. Equally distributed nanosized MnO particles and the porous carbon matrix have fully developed a synergistic effect to achieve superior lithium ion storage performance. Using the MnO/C nanocomposite material as the anode of a Li-ion battery, a high discharge capacity of 952 mA h g−1 has been obtained at a current density of 0.1 A g−1 with a stable cycling performance over 100 charge–discharge cycles.

Solvothermally induced α-Fe2O3/graphene nanocomposites with ultrahigh capacitance and excellent rate capability for supercapacitors

Well crystallized Fe2O3 with the particle size mainly concentrated around 35–40 nm combined with graphene is fabricated under solvothermal conditions. The optimized Fe2O3/GH-2 composite sample possessing 49.7 wt% Fe2O3 has a high specific BET surface area of 215.3 m2 g−1. When used as a supercapacitor electrode, the capacitances are admirable 2310 F g−1 at 5 mV s−1 and 615 F g−1 at an amazingly high current density of 100 A g−1. When used as an anode material for asymmetric hybrid capacitors, the composite shows a promising future for energy storage with high energy density, high power density and excellent cycle life.