13 research outputs found
Anchoring ultrafine Co3O4 grains on reduced oxide graphene by dual-template nanocasting strategy for high-energy solid state supercapacitor
Co3O4-based materials are regarded as superior electrode candidates in various energy storage devices due to their high theoretical capacity. Unfortunately, the poor electronic conductivity and huge volume expansion hamper their widespread applications. Therefore, nano-processing and introducing conductive matrix can view as the necessary methods to make Co3O4-based materials better for an advanced supercapacitor electrode. Herein, a dual-template nanocasting technique is proposed to design the ultrafine Co3O4 grains highly-dispersed on the reduced oxide graphene nanosheets (Co3O4/rGO-C), in which cetyltrimethyl ammonium bromide and silicate species are hired as the ideal soft and hard template, respectively. Co3O4 grains with size \u3c10âŻnm can expose more active sites and thus exert more redox activities to enhance the capacitive performance. In additional, âź4âŻnm moderate pores are obtained in Co3O4/rGO-C after the hard template removing, which provides more diffusion channels for ion/electron rapid transport and also effectively alleviates the volume expansion on cycling. Consequently, the Co3O4/rGO-C electrode exhibits a remarkable specific capacitance (709.1âŻFâŻgâ1 at 1âŻAâŻgâ1) and long-term endurance (91.2% after 6000 cycles). Furthermore, an assembled solid-state asymmetric device of Co3O4/rGO-C||rGO delivers a super-high energy-density of 48.2âŻWh kgâ1 at 750.5âŻWâŻkgâ1. The high energy-density assists two devices in lightning a red light-emitting diode for 340âŻs. These results evidence the nanocasting strategy as an efficient method to achieve the advanced electrode materials for energy storage devices
Chitosan-confined synthesis of N-doped and carbon-coated Li4Ti5O12 nanoparticles with enhanced lithium storage for lithium-ion batteries
Using chitosan as the carbon and nitrogen source, highly-crystalline lithium titanate nanoparticles with N-doped carbon-coating (N-C/LTO) have been successfully synthesized via a facile refluxing and microwave-assisted hydrothermal processes followed by a subsequent calcination step. Due to the effect of chitosan-confined, the fabricated N-C/LTO composites crystallized into well-defined cubic spinel structure with an average size of âź50Â nm, leading to a significantly enhanced specific surface area. The successful doping of nitrogen into the carbon layer of the N-C/LTO has been confirmed by XPS technology. The porous LTO with nitrogen-doped carbon coating fabricated with chitosan exhibits superior electrochemical performance (a high reversible capacity of 194 mAh gâ1 was achieved at 1 C). This work therefore reveals that the N-doped carbon coating realized by chitosan confinement is an effective way for enhancing the surface lithium storage capability of LTO as the anode materials for lithium-ion batteries (LIBs)
MnO2-introduced-tunnels strategy for the preparation of nanotunnel inserted hierarchical-porous carbon as electrode material for high-performance supercapacitors
Nanotunnels inserted hierarchical-porous carbon (NTHPC) have been synthesized successfully via a MnO2-introduced-tunnels strategy using MnO2 nanorods as template, with agar and β-cyclodextrin serving as hybrid carbon precursors. The as-prepared NTHPC possesses a higher specific surface area of 1441 m2 gâ1, a moderate pore volume of 1.23 cm3 gâ1, and the hierarchical-porous structure with inserted nanotunnels. Transmission electron microscopy has demonstrated that the width of the nanotunnels is between 20 and 100 nm, and the length ranges from 0.2 to 2.0 Îźm. Tests in a three-electrode system showed that the NTHPC has high specific capacitance (253.1 F gâ1, 5 mV sâ1), as well as good rate capability (203.3 F gâ1, 100 mV sâ1) and excellent cycling stability. More importantly, an assembled symmetric supercapacitor with NTHPC electrodes delivered an outstanding energy density of up to 34.9 Wh kgâ1 with power density of 755.2 W kgâ1. The remarkable electrochemical performance of the NTHPC is ascribed to the nanotunnels, which act as ion reservoirs and liquid transfer channels that can increase the ion transport rate and shorten the ion transfer distance. This study provides a novel method for the preparation of high-performance hierarchical-porous carbon and guidance for its potential applications in supercapacitors
3D sandwiched nanosheet of MoS2/C@RGO achieved by supramolecular self-assembly method as high performance material in supercapacitor
A new type of sandwiched nanosheets 3D MoS2/C@RGO is synthesized by supramolecular self-assembly methods, as a novel and excellence electrode material. The surface characterization techniques show that the sandwiched 3D MoS2/C@RGO possesses rich porosity and large specific area, which is convenient for electrolyte ion transportation and beneficial for the improved electrical conductivity. An outstanding specific capacitance of the prepared MoS2/C@RGO of 340.0 F/g at 1 A gâ1 is achieved with an excellent cycle stability of 90% after 1000 cycles at the scanning rate of 40 mV/s. The sandwiched 3D MoS2/C@RGO is suggested to be an ideal candidate for supercapacitors
An Ultrasensitive Immunosensor for the Detection of Carcinoembryonic Antigens Utilizing a Nb-Doped Titanium Dioxide Nanocomposite Film
Molecular Breeding of Water-Saving and Drought-Resistant Rice for Blast and Bacterial Blight Resistance
Rice production is often affected by biotic and abiotic stressors. The breeding of resistant cultivars is a cost-cutting and environmentally friendly strategy to maintain a sustainable high production level. An elite water-saving and drought-resistant rice (WDR), Hanhui3, is susceptible to blast and bacterial blight (BB). This study was conducted to introgress three resistance genes (Pi2, xa5, and Xa23) for blast and BB into Hanhui3, using marker-assisted selection (MAS) for the foreground selection and a whole-genome single-nucleotide polymorphism (SNP) array for the background selection. As revealed by the whole-genome SNP array, the recurrent parent genome (RPG) recovery of the improved NIL was 94.2%. The resistance levels to blast and BB of the improved NIL and its derived hybrids were higher than that of the controls. In addition, the improved NIL and its derived hybrids retained the desired agronomic traits from Hanhui3, such as yield. The improved NIL could be useful to enhance resistance against biotic stressors and produce stable grain yields in Oryza sativa subspecies indica rice breeding programs
Preparation of Lithium Titanate/Reduced Graphene Oxide Composites with Three-Dimensional âFishnet-Likeâ Conductive Structure via a Gas-Foaming Method for High-Rate Lithium-Ion Batteries
With
use of ammonium chloride (NH<sub>4</sub>Cl) as the pore-forming agent,
three-dimensional (3D) âfishnet-likeâ lithium titanate/reduced
graphene oxide (LTO/G) composites with hierarchical porous structure
are prepared via a gas-foaming method. Scanning electron microscopy
and transmission electron microscopy images show that, in the composite
prepared with the NH<sub>4</sub>Cl concentration of 1 mg mL<sup>â1</sup> (1-LTO/G), LTO particles with sizes of 50â100 nm disperse
homogeneously on the 3D âfishnet-likeâ graphene. The
nitrogen-sorption analyses reveal the existence of micro-/mesopores,
which is attributed to the introduction of NH<sub>4</sub>Cl into the
gap between the graphene sheets that further decomposes into gases
and produces hierarchical pores during the thermal treatment process.
The loose and porous structure of 1-LTO/G composites enables the better
penetration of electrolytes, providing more rapid diffusion channels
for lithium ion. As a result, the 1-LTO/G electrode delivers an ultrahigh
specific capacity of 176.6 mA h g<sup>â1</sup> at a rate of
1 C. Even at 3 and 10 C, the specific capacity can reach 167.5 and
142.9 mA h g<sup>â1</sup>, respectively. Moreover, the 1-LTO/G
electrode shows excellent cycle performance with 95.4% capacity retention
at 10 C after 100 cycles. The results demonstrate that the LTO/G composite
with these properties is one of the most promising anode materials
for lithium-ion batteries
Preparation of Lithium Titanate/Reduced Graphene Oxide Composites with Three-Dimensional âFishnet-Likeâ Conductive Structure via a Gas-Foaming Method for High-Rate Lithium-Ion Batteries
With
use of ammonium chloride (NH<sub>4</sub>Cl) as the pore-forming agent,
three-dimensional (3D) âfishnet-likeâ lithium titanate/reduced
graphene oxide (LTO/G) composites with hierarchical porous structure
are prepared via a gas-foaming method. Scanning electron microscopy
and transmission electron microscopy images show that, in the composite
prepared with the NH<sub>4</sub>Cl concentration of 1 mg mL<sup>â1</sup> (1-LTO/G), LTO particles with sizes of 50â100 nm disperse
homogeneously on the 3D âfishnet-likeâ graphene. The
nitrogen-sorption analyses reveal the existence of micro-/mesopores,
which is attributed to the introduction of NH<sub>4</sub>Cl into the
gap between the graphene sheets that further decomposes into gases
and produces hierarchical pores during the thermal treatment process.
The loose and porous structure of 1-LTO/G composites enables the better
penetration of electrolytes, providing more rapid diffusion channels
for lithium ion. As a result, the 1-LTO/G electrode delivers an ultrahigh
specific capacity of 176.6 mA h g<sup>â1</sup> at a rate of
1 C. Even at 3 and 10 C, the specific capacity can reach 167.5 and
142.9 mA h g<sup>â1</sup>, respectively. Moreover, the 1-LTO/G
electrode shows excellent cycle performance with 95.4% capacity retention
at 10 C after 100 cycles. The results demonstrate that the LTO/G composite
with these properties is one of the most promising anode materials
for lithium-ion batteries