Search

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O2 batteries. Herein, a novel bifunctional photo-assisted Li-O2 system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O2 batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O2 batteries exhibits a high rate (129 % round-trip efficiency at 1 mA cm-2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g-1 at 0.75 mA cm-2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.

As a conductive polymer with great potential, poly(3,4-ethylenedioxythiophene) (PEDOT) has been developed as a high-rate supercapacitor electrode but stores less energy due to its limited theoretic...

Molybdenum sulfide (MoS2) is a representative transition-metal chalcogenide holding great potential in electrochemical energy devices. However, poor conductivity and limited stability hinder practi...

By using Ti3C2Tx quantum dots as interlayer spacers, Ti3C2Tx nanosheets/Ti3C2Tx quantum dots/RGO (reduced graphene oxide) fiber (M6M3RG1) is prepared by a wet-spinning method; it shows good capacit...

Lithium sulfur batteries are expected to be one of the most promising energy storage systems due to their high energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides severely hampers their practical application. The design of the sulfur cathode is one of the most important approaches to overcome the problem. In this work, MoS2 nanosheets have been successfully grown on the surface of hollow carbon spheres (HCS) to obtain MoS2@HCS nanocomposites with uniform morphology. The growth behavior of MoS2 nanosheets was also proved by adjusting the pore structure of HCS. With a sulfur loading of 74%, the MoS2@HCS/S cathode exhibits a high initial reversible capacity of 1419 mA h g-1 at a current density of 0.1 C and remains at 1010 mA h g-1 after 100 cycles. Even at 0.5 C, a capacity of 795 mA h g-1 can be retained after 600 cycles, corresponding to a capacity retention rate of 63.1%. By adjusting the concentration of the sulfur source, the relationship between different growth quantities of MoS2 and the cycling performance of the battery was also investigated. The excellent electrochemical performance of the MoS2@HCS/S cathode can be fully attributed to its physical and chemical double adsorption effect on lithium polysulfides, which has been confirmed through the visible adsorption and X-ray Photoelectron Spectroscopy (XPS) experiments. This work provides a simple design concept and method to synthesize a nanocomposite-based sulfur host for high performance lithium sulfur batteries.

This work reports a facile method to prepare N-doped carbon sheets that are uniformly coated on the surface of CoNiO2@activated textile carbon (CS-CoNi@aTC). We used easily polymerized dopamine as the carbon precursor and hierarchical NiCo-LDH nanosheets grown on activated textile carbon as the flexible substrate. The subsequent thermal annealing treatment at 400 °C in a nitrogen atmosphere converts polydopamine into amorphous N-doped carbon and simultaneously decomposes the NiCo-LDH into CoNiO2. Both the thickness and mass loading of carbon sheets can be facilely controlled by changing the concentration of dopamine. Besides enhancing the areal capacitance of aTC by adding pseudocapacitance, these carbon sheets also significantly enhance the cycling stability of CoNiO2 through reinforcing the interfacial coupling of CoNiO2 nanosheets and carbon fibers. Acid etching of CoNiO2 leaves behind vertical carbon sheets connected on the aTC substrate (CS@aTC). An aqueous asymmetric supercapacitor (ASC) built with CS-CoNi@aTC and CS@aTC can exhibit remarkable cycling stability with 93% capacitance retention and 100% coulombic efficiency after continuous charging–discharging for 45 000 cycles. An assembled solid-state ASC delivers an areal capacitance of 284 mF cm−2 and a maximum volumetric energy density of 1.4 mW h cm−3 while exhibiting good flexibility and mechanical robustness.

As the next generation of electrochemical energy storage devices, lithium sulfur (Li–S) batteries have many advantages such as high theoretical specific capacity (1675 mAh g−1) and energy density (2600 kw h kg−1), non-toxicity and low cost. However, the poor electrical conductivity of sulfur cathodes and the shuttling effect of lithium polysulfides during cycling strongly hinder the commercial application of Li–S batteries. In this study, Magneli phase Ti4O7 nanoparticles were successfully prepared on the surface of hollow carbon spheres (HCS) through a carbothermal reduction reaction. The synthesized HCS@Ti4O7 with a mesoporous structure exhibited a uniform spherical morphology with a large specific surface area (512 m2 g−1) and the pore volume of 0.58 cm3 g−1. The introduction of a polydopamine (PDA) layer during the preparation was confirmed to effectively inhibit the grain coarsening of Ti4O7. Moreover, the high content of sulfur loading (70%) did not affect the morphology of HCS@Ti4O7, which suggested its stable architecture. The assembled coin cells exhibited the superior reversible capacity of 1427 mAh g−1 at 0.1C and favorable cycling stability from 1168 mAh g−1 to 601 mAh g−1 after 800 cycles at 0.5C with the capacity decay rate of only 0.06% per cycle. This excellent performance and stability were attributed to the strong chemical binding effects of Ti4O7 on lithium polysulfides and the stable morphology maintenance during cycling. This study provides a novel conception to design and synthesize nanocomposites between reduced metal oxides and carbon with uniform and stable mesoporous structures for high-performance Li–S batteries.

The preparation of two-dimensional boron (B) nanosheets, especially for borophene, is still a challenge because of its unique structure and complex B–B bonds in bulk boron. In the present work, a novel preparation technology for borophene with only a few layers and large flake sizes is developed by a solvothermal-assisted liquid phase exfoliation process, consisting of ball milling-thinning, solvothermal swelling, and probe ultrasonic delamination. The exfoliation effect of the bulk B precursors is related to the surface tension and Hildebrand parameter of the selected solvents such as acetone, N,N-dimethyl formamide (DMF), acetonitrile, ethanol, and N-methyl pyrrolidone (NMP), and a relative small surface tension when using solvents is favorable for the exfoliation of bulk B. Four-layer thick borophene and an average lateral size of 5.05 μm can be obtained in acetone as the exfoliating solvent. The surface composition of the exfoliated few-layer borophene with large flake size hardly changes, while the chemical state of B changes to some extent because they are partly oxidized on the surface by contaminates before and after exfoliation. This acetone solvothermal-assisted liquid phase exfoliation technique can be used to prepare high quality borophene with large horizontal sizes, and it will provide the basis to study few-layer borophene with large sizes further.

In this work, several Mn-doped Co2P/N-doped carbon composite materials were facilely prepared through one-step carbonizing and phosphating treatments. The catalysts have exhibited high bifunctional catalytic activities for OER and ORR. Notably, the optimized catalyst Mn(0.1)-Co2P/NC exhibited high electrocatalytic activities for ORR (with onset/half-wave potential of 0.856/0.784 V vs. RHE, respectively) and OER (with an overpotential of 370 mV at 10 mA/cm2), which are very near to those of Pt/C (20%) and RuO2 noble catalyst, respectively. When the Mn(0.1)-Co2P/NC was employed as air electrode catalyst for rechargeable Zn-air battery, the battery exhibited a high open-circuit voltage of 1.351 V, a stable discharge voltage of 1.08 V, a high round-trip efficiency of 47.3% and excellent stability for 100 cycles at 10 mA/cm2, which is superior to the one using Pt/C (20%) + RuO2 as the air electrode catalyst.

Sodium-ion capacitors (SICs) have gained great interest for mid- to large-scale energy storage applications because of their high energy and high power densities as well as long cycle life and low cost. Herein, a T-Nb2O5 nanoparticles/N-doped graphene hybrid anode (T-Nb2O5/NG) was prepared by solvothermal treating a mixed ethanol solution of graphene oxide (GO), urea, and NbCl5 at 180 °C for 12 h, followed by calcining at 700 °C for 2 h, in which T-Nb2O5 nanoparticles with average size of 17 nm were uniformly anchored on the surface of the nitrogen-doped reduced GO because their growth and aggregation were hindered, and also, the electronic conductivity and the active sites of T-Nb2O5/NG were improved by doping nitrogen. The T-Nb2O5/NG anode showed superior rate capability (68 mA h g–1 even at 2 A g–1) and good cycling life (106 mA h g–1 at 0.2 A g–1 for 200 cycles and 83 mA h g–1 at 1 A g–1 for 1000 cycles) and also showed high-rate pseudocapacitive behavior from kinetics analysis. A novel SIC system had been constructed by using the T-Nb2O5/NG as anode and commercially activated carbon as the cathode; it delivered an energy density of 40.5 W h kg–1 at a power density of 100 W kg–1 and a long-term cycling stability (capacity retention of 63% after 5000 consecutive cycles at a current density of 1 A g–1) and showed a promising application for highly efficient energy storage systems.

Mn3O4/reduced graphene oxide/single-walled carbon nanotube flexible hybrid film with outstanding flexibility and electrochemical performance is prepared via a vacuum filtration method. The three-dimensional interconnect structure is constructed by reduced graphene oxide and single-walled carbon nanotube, and Mn3O4 nanoplates with pesudocapacitance are embedded into the interconnect structure. The regular interconnect structure and a synergetic effect between graphene oxide/single-walled carbon nanotube and Mn3O4 make the Mn3O4/reduced graphene oxide/single-walled carbon nanotube flexible film electrode exhibit a large areal capacitance of 796 mF cm−2. All-solid-state Mn3O4/reduced graphene oxide/single-walled carbon nanotube flexible supercapacitor is prepared by using the hybrid film as electrodes and sandwiching the PVA–KOH gel electrolyte, it exhibits a large area specific capacitance of 360 mF cm−2 and the capacitance maintains 95% after 5000 charge/discharge cycles. The assembled supercapacitor exhibits both outstanding mechanical performance and a high areal energy density of 32 μW h cm−2 at an areal power density of 0.392 mW cm−2. The Mn3O4/reduced graphene oxide/single-walled carbon nanotube flexible supercapacitors exhibit significant potentiality in flexible and wearable electronics owing to their excellent flexibility, high energy density and long cycle life.

Graphitic carbon nitride (g-C3N4) has been believed to be a promising photocatalyst for water splitting due to its right band gap and band edges. However, the kinetics of hydrogen evolution on g-C3N4 is very slow. Cocatalysts are usually needed to improve the catalytic kinetics. Herein, palladium-doped graphitic carbon nitride (g-C3N4–Pd) is designed by virtue of the tenacious coordination of Pd atoms with the pyridinic nitrogen atoms of six-fold cavities in g-C3N4. The introduction of Pd does not affect the structure and morphology of g-C3N4. Palladium is found to exist as Pd ions in g-C3N4–Pd catalysts. g-C3N4–Pd catalysts exhibit clearly higher hydrogen evolution activities than g-C3N4. The highest hydrogen evolution activity on g-C3N4–Pd is 15.3 times that of g-C3N4. The improvement of hydrogen evolution activity is found to arise from both the alternation of the electron excitation manner and the acceleration of hydrogen evolution kinetics induced by Pd doping. Our findings provide a promising way to...

H 2 SO 4 + Fe 3+ /Fe 2+ electrolyte was selected as redox active electrolyte and PANI with nanoflower morphology was used as porous active material electrode, symmetric PANI supercapacitor (SC) has been assembled and the enhanced behaviors of H 2 SO 4 + Fe 3+ /Fe 2+ redox active electrolyte on the capacitance, energy density, and the cycling stability of PANI SC were systematically investigated. In the present work, the specific capacitance of symmetric PANI SC is heightened to 1062 F g −1 in 1 M H 2 SO 4 + 0.8 M Fe 3+ /Fe 2+ redox active electrolyte at an applied current density of 2 A g −1 , which is three times as high as that in 1 M H 2 SO 4 electrolyte. Moreover, the PANI nanoflower symmetric SC exhibits an improved energy density as high as 22.1 Wh kg −1 at a power density of 774.0 W kg −1 , and delivers the capacitance retention of 93% after 10000 charge-discharge cycles. The H 2 SO 4 + Fe 3+ /Fe 2+ redox active electrolyte can also enhance the capacitive performance of RGO double layer SC. These encouraging results suggest that H 2 SO 4 + Fe 3+ /Fe 2+ redox active electrolyte can be used as a prospective measure for improving the electrochemical performance of SCs for large-scale energy storage.

A simple yet efficient one-step route is reported to prepare a three-dimensional interconnected thin-layer carbon network consisting of graphene sheets sandwiched by a porous carbon layer (PCG). Our route relies on the direct pyrolysis of ethylene diamine tetraacetic acid tripotassium salt (EDTA-3K) in the presence of polyelectrolyte-functionalized graphene oxide (GO) at 750 °C. The decomposition of EDTA-3K at elevated temperature yields carbon and potassium species, which in turn serves as an activation agent to generate highly porous carbon layer on graphene sheets. Due to the reduced ion diffusion length, improved wettability and electrical conductivity, PCG electrode exhibits a higher specific capacitance, better rate capability together with smaller ion transport resistance in both aqueous KOH and organic electrolyte as compared with the counterpart carbon electrode prepared by direct pyrolysis of EDTA-3K in the absent of GO. Moreover, PCG electrode shows excellent cycling stability with 97% and 94.3% capacitance retention after 20,000 and 5000 consecutive charge-discharge cycles in aqueous and non-aqueous electrolytes, respectively. Further constant voltage floating experiment by holding the cell voltage at 2.5 V for 200 h confirms the high stability of PCG electrode in TEABF 4 /AN electrolyte. These performance demonstrate that PCG hybrid could be one of promising candidates for electrochemical energy storage.

Ti3C2Tx nanosheets/reduced graphene oxide (Ti3C2Tx/RGO-0.9) fiber with superior flexibility and high volumetric capacitance is prepared by spinning the suspension of Ti3C2Tx nanosheets and graphene oxide (GO) nanosheets and followed by treating in HI solution at 80 °C. The oxidation of Ti3C2Tx nanosheets can be effectively protected in N2 atmosphere at 5 °C, and the as-prepared Ti3C2Tx/RGO-0.9 fiber electrode shows a specific volume capacitance of 415 F cm−3 at a current density of 1 A cm−3 in 1 M H2SO4 electrolyte and superior flexibility. Ti3C2Tx/RGO//PANI (polyaniline)/RGO all-solid-state asymmetrical fiber supercapacitor (AFSC) is assembled by using Ti3C2Tx/RGO-0.9 fiber as negative electrode and PANI/RGO-0.4 fiber as positive electrode in PVA-H2SO4 gel electrolyte, it exhibits not only excellent volumetric capacitance of 25 F cm−3 at a current density of 20 mA cm−3, but also high energy density of up to 3.4 mWh cm−3 at a power density of 10.2 mW cm−3. Moreover, the assembled AFSC shows outstanding flexibility and mechanical property, its volumetric capacitance has no obvious change after bending 500 times. The high energy density and superior mechanical flexibility make it can be used as a promising flexible power source in the fields of portable wearable electronic devices.

Ti2Nb2O9/reduced graphene oxide (Ti2Nb2O9/RGO) hybrid anode is fabricated by flocculation of HTiNbO5 nanosheets and graphene oxide (GO) nanosheets, followed by annealing HTiNbO5/GO composite at 500 °C in Ar for 1 h, in which HTiNbO5 nanosheets are prepared by ion-exchange and followed by exfoliating process using KTiNbO5 as precursor. HTiNbO5 nanosheets are topotactically transformed into Ti2Nb2O9 nanosheets and GO is reduced into RGO by calcining the HTiNbO5/GO composite, causing enhanced Na+-intercalation pseudocapacitive behavior and significantly improved conductivity for Ti2Nb2O9/RGO hybrid anode. Ti2Nb2O9/RGO hybrid anode delivers superior rate capability (206 mAh g−1 at 4 A g−1) and excellent cycling performance with 95% capacity retention at 1 A g−1 over 1000 cycles. A hybrid device is assembled using Ti2Nb2O9/RGO as the anode and activated carbon (AC) as the cathode, it shows a maximum high energy density of 96 Wh kg−1 at a power density of 75 W kg−1, and the energy density still maintains 39 Wh kg−1 when the power density achieves as high as 10029 W kg−1. Moreover, the assembled device displays good cycling stability with a capacity retention of 79% after 10,000 cycles. This work can provide new insights on fabrication of Ti-Nb oxides-graphene based composite anode for sodium ion capacitors.

Highly flexible all-solid-state cable-type supercapacitors based on Cu/reduced graphene oxide/manganese dioxide fibers (Cu/RGO/MnO2) were successfully assembled by closely placing two Cu/RGO/MnO2 fibers in a parallel direction and using PVA–KOH gel electrolyte, in which the Cu/RGO/MnO2 fiber electrode, possessing good flexibility, excellent electrochemical properties, and high electrical conductivity was prepared by heating a glass pipeline filled with a Cu wire and a graphene oxide homogenous suspension at 230 °C for 2.5 h. The Cu/reduced graphene fiber was then refluxed in KMnO4 solution at 70 °C for 120 min. As well as being used as a current collector, the Cu wire also served as the matrix for depositing active materials and improving the fiber flexibility, causing a high-quality interfacial contact between the current collector and the active materials. The optimized all-solid-state Cu/RGO/MnO2(6.0) fiber supercapacitor showed a high specific capacitance of 140 mF cm−2 at a current density of 0.1 mA cm−2, enhanced capacitance retention of 97% after 500 bending cycles with a big angle of 120°, and relatively good stability (88% of initial capacitance values after 5000 cycles). Moreover, aside from its excellent electrochemical performance, it could light a LED lamp when connected with a battery, indicating that the assembled Cu/RGO/MnO2 fiber supercapacitor could be used not only as an energy storage device, but also an electrical conduction cable, which could have a significant impact on future energy storage applications.

Despite showing great promise in bioapplications, lanthanide-doped upconversion nanoparticles (UCNPs) are still restricted by low upconversion efficiency. In this work, ultra-small, monodisperse and uniform β-NaYbF4:0.5% Tm NPs were successfully prepared through a solvothermal route, and remarkably enhanced ultraviolet upconversion luminescence (UV UCL) had been achieved via Fe3+ doping. The UV UCL enhancement in NaYbF4:0.5% Tm NPs was investigated in detail. It was found that the UCL intensities of the UV and blue emissions of NPs doped with 5 mol% Fe3+ ions were enhanced by 10 and 6 times, respectively, compared to that of the Fe3+-free sample. The enhancement of UV UCL is mainly ascribed to the high population density of excited Yb3+ and the energy transfer from |2F7/2, 4T1g > (Yb3+–Fe3+ dimer) to 3F2,3 (Tm3+) states. Moreover, through dynamic analysis, we further demonstrate the proposed mechanisms of UC processes. The results suggest that ultra-small UCNPs with enhanced UV UCL may have potential applications in the biomedical field.

Holey graphene/polypyrrole hybrid aerogels (HGPAs) with three-dimensional (3D) hierarchical structure have been fabricated by freeze-drying holey graphene/polypyrrole hydrogels, which are assembled by using holey graphene (HG) nanosheets and polypyrrole (PPy) nanoparticles as assembling primitives. The as-prepared HGPAs materials show an interconnected and stable 3D porous network, and PPy nanoparticles uniformly embedded in the aerogel prevent the restacking of holey graphene (HG) nanosheets. The unique hierarchical porous structure and synergistic effect between PPy nanoparticles and HG nanosheets make HGPA hybrid aerogel electrode with a mass ratio of PPy/HGO = 0.75 exhibits high specific capacitance (418 F g −1 ) at a current density of 0.5 A g −1 , extremely outstanding rate capability (80%) at various current densities from 0.5 to 20 A g −1 and good cycling performance (74%) after 2000 cycles in 1.0 M KOH aqueous electrolyte. Moreover, the effect of the PPy nanoparticle sizes in HGPAs on their electrochemical properties is also investigated, and PPy nanoparticles with relatively larger sizes are favorable of the good capacitive performance for the obtained electrodes. The facile and efficient preparation method for HGPAs electrodes may be developed for preparing other holey graphene-based hybrid aerogels with structure-controllable nanostructures.

Hollow carbon fibers (aCFs) with a high specific surface area are applied as conductive scaffolds for polyaniline (PANi) growth. aCFs oxidized by HNO3 treatment have more surface negative charges, which interact with protonated aniline molecules in acidic media. The subsequent chemical oxidative polymerization assisted by (NH4)2S2O8 yields aCF–PANi composites with PANi nanorod arrays strongly coupled on both the external and internal surfaces of the aCFs. Serving as binder-free supercapacitor electrode, the aCF–PANi composite with 31 wt % PANi exhibits a specific capacitance of 364 F g−1, and retains 70 % of this value at 20 A g−1. More interestingly, it exhibits excellent cycling stability with 92.5 % capacitance retention, and outstanding reversibility with 98.6 % coulombic efficiency, even after 5000 continuous cycles; this performance is far superior to that of both aCF and PANi electrodes. The strongly coupled PANi arrays on the aCF surface greatly reduce the interface resistance, thus facilitating both ion and electron transport for enhanced capacitive performance.

Electrocatalysts play an important role in oxygen reduction reaction (ORR) in promoting the reaction process. Although commercial Pt/C exhibits excellent performance in ORR, the low duration, high cost, and poor methanol tolerance seriously restrict its sustainable development and application. TinO2n&minus, 1 (3 &le, n &le, 10) is a series of titanium sub-oxide materials with excellent electrical conductivity, electrochemical activity, and stability, which have been widely applied in the field of energy storage and catalysis. Herein, we design and synthesize Ti4O7/Ti3O5 (T4/T3) dual-phase nanofibers with excellent ORR catalytic performance through hydrothermal growth, which is followed by a precisely controlled calcination process. The H2Ti3O7 precursor with uniform size can be first obtained by optimizing the hydrothermal growth parameters. By precisely controlling the amount of reducing agent, calcination temperature, and holding time, the T4/T3 dual-phase nanofibers with uniform morphology and coherent interfaces can be obtained. The orientation relationships between T4 and T3 are confirmed to be [ 001 ] T 3 / / [ 031 ] T 4 , ( 100 ) T 3 / / ( 92 6 &macr, ) T 4 , and ( 010 ) T 3 / / ( 1 2 &macr, 6 ) T 4 , respectively, based on comprehensive transmission electron microscopy (TEM) investigations. Furthermore, such dual-phase nanofibers exhibit the onset potential and half-wave potential of 0.90 V and 0.75 V as the ORR electrocatalysts in alkaline media, respectively, which illustrates the excellent ORR catalytic performance. The rotating ring-disk electrode (RRDE) experiment confirmed the electron transfer number of 3.0 for such catalysts, which indicates a mixture of two electron and four electron transfer reaction pathways. Moreover, the methanol tolerance and cycling stability of the catalysts are also investigated accordingly.

As a green pollution-free reaction, oxygen reduction reaction (ORR) plays a significant role in many energy storage and conversion devices. Although commercial Pt/C possesses the highest ORR activity (especially in acidic medium), the high cost, low stability and poor methanol tolerance making the development of non-platinum electrocatalysts with high performance especially important. Herein, we design and synthesize a carbon nanofiber decorated by Ti4O7/Ti3O5 dual-phase nanoparticles (CNF/T4/T3) as ORR catalysts with excellent activity. With the employment of electrospinning followed by precisely controlled calcination process, the composite catalysts with uniform fibrous morphology can be obtained. Such CNF/T4/T3 composite catalysts exhibited an improved electrochemical performance with onset and half-wave potential of 0.91 V and 0.78 V respectively in alkaline solution. By comparing the catalytic performance with the pure T4 or T3 phase decorated on the same carbon nanofiber, it is found that the mixture of the two titanium sub-oxide phases can optimize the onset potential and limited current density at the same time. Density functional theory calculations suggest that different steps of ORR take place on T3 and T4 successively, which is the main reason of the excellent ORR performance for the dual-phase structure. This work provided a novel designing concept for the functional electrocatalysts using electrospinning technique for the application of energy storage and conversion.

Carbonized wood (CW) achieved by the pyrolysis of various nature woods has received ever-increasing attentions in energy storage and conversion. However, its charge storage capacity is rather low because of its intrinsic ion adsorption mechanism. This work reports the enhanced capacitive performance of CW by growing electroactive FeOOH nanosheets and coating conductive poly(3,4-ethylenedioxythiophene) (PEDOT) network. Those vertically grown FeOOH nanosheets on both the external surface and inside the channel of CW offer more opened active sites for Faradaic reactions, whereas the porous and conductive PEDOT network significantly boosts the electrode conductivity, facilitates the ion transport, and protects the FeOOH sheets from destruction during cycling. Accordingly, the CW-FeOOH-PEDOT ternary electrodes exhibit 4.3 times higher volumetric capacitance than the CW electrode and remain at 90% capacitance upon increasing the current density from 10 to 50 mA cm–2. Remarkably, the electrode maintains 103% of ...

The development of compressible supercapacitor highly relies on the innovative design of electrode materials with both superior compression property and high capacitive performance. This work reports a highly compressible supercapacitor electrode which is prepared by growing electroactive NiCo2S4 (NCS) nanosheets on the compressible carbon sponge (CS). The strong adhesion of the metallic conductive NCS nanosheets to the highly porous carbon scaffolds enable the CS–NCS composite electrode to exhibit an enhanced conductivity and ideal structural integrity during repeated compression–release cycles. Accordingly, the CS–NCS composite electrode delivers a specific capacitance of 1093 F g–1 at 0.5 A g–1 and remarkable rate performance with 91% capacitance retention in the range of 0.5–20 A g–1. Capacitance performance under the strain of 60% shows that the incorporation of NCS nanosheets in CS scaffolds leads to over five times enhancement in gravimetric capacitance and 17 times enhancement in volumetric capaci...

MnOx nanocrystalline/graphene hybrid electrodes are prepared by exchanging graphene oxide (GO) with Mn2+ ions and followed by calcining the Mn2+ ⿿exchanged material (Mn2+⿿GO) at different temperatures in N2 atmosphere. The effect of the calcining temperatures on the phase and morphology of the obtained materials is investigated. The phase and size of MnOx nanocrystalline and the reduction degree of GO in MnOx nanocrystalline/graphene hybrids are affected by calcining temperature. Mn3O4/RGO⿿450 hybrid electrode with a little of wrinkle degree of the reduced graphene oxide (RGO) is obtained when sample Mn2+⿿GO was calcined at 450 °C, in which Mn3O4 nanocrystalline with average size of 13.5 nm are homogeneously distributed on the surface of RGO. The electrochemical properties of MnOx nanocrystalline/graphene hybrid electrodes are investigated by cyclic voltammetry and galvanostatic charge⿿discharge in 1 M KOH electrolyte. Their electrochemical performance is highly structure dependent and the highly utilization of MnOx nanocrystalline. The Mn3O4/RGO⿿450 hybrid electrode exhibits a high specific capacitance of 517 F g⿿1 at a current density of 1 A g⿿1. This method can be expanded to control the size of other transition⿿metal oxide nanocrystalline on the graphene nanosheets and improve the capacitance and utilization of the metal oxide⿿graphene nanohybrids.

Holey graphene with abundant in-plane nanopores is achieved through a mild defect-etching reaction between graphene oxide (GO) and hydrogen peroxide (H 2 O 2 ) then followed by a reduction process in hydrazine solution. The porosity of the obtained holey graphene is systematically investigated by optimizing the reaction conditions between GO and H 2 O 2 . The optimum reaction conditions are that GO is hydrothermally treated in 0.4 mL H 2 O 2 at 100 °C for 10 h and the as-prepared holey graphene oxide (HGO) is refluxed in hydrazine solution at 100 °C for 1 h, by which holey reduced graphene oxide (HRGO) suspension with good dispersity is obtained. By vacuum filtration of the HRGO suspension, the binder-free porous graphene film electrodes are successfully assembled. The obtained film electrodes exhibit high specific capacitance (251 F g −1 at a current density of 1 A g −1 ), high volumetric capacitance (up to 216 F cm −3 ), and enhanced rate capability (73% capacitance retention from 1–60 A g −1 ) due to their high packing density (0.86 g cm −3 ). The suitable porosity of the assembled porous graphene film keeps a balance between electrolyte ion diffusion rate and conductivity, which can bridge the gap between gravimetric capacitance and volumetric capacitance for the obtained electrode material.

δ-MnO2/holey reduced graphene oxide (HRGO) fiber electrodes with good flexibility and enhanced electrochemical performance were prepared by depositing δ-MnO2 on the surface of the holey reduced graphene oxide fibers. HRGO-650 was obtained by soaking graphene oxide in a 0.5 M H3PO4 solution for 12 h followed by calcining it at 650 °C for 2 h in N2. The loose curling manganese oxide nanosheets are reassembled on the surface of the HRGO-650 fiber freely, causing the close contact between the manganese oxide nanosheets and the graphene nanosheets. The prepared δ-MnO2(4.0)/HRGO fiber electrode shows a larger specific capacitance (245 F g−1) at a current density of 1 A g−1 in the 1 M Na2SO4 electrolyte. An all-solid-state fiber supercapacitor was assembled by two intertwined δ-MnO2(4.0)/HRGO fiber electrodes, both of which are solidified in a H3PO4–polyvinyl alcohol (PVA) gel electrolyte. This all-solid-state δ-MnO2(4.0)/HRGO fiber supercapacitor not only shows good flexibility, but also gives enhanced capacitive performance. The optimal all-solid-state δ-MnO2(4.0)/HRGO fiber supercapacitor obtains a high area-specific capacitance (16.3–16.7 mF cm−2) at a current density of 0.05 mA cm−2, enhanced rate capability (64% capacitance retention from 0.05–0.6 mA cm−2), and relative good stability (80% of initial capacitance values after 1000 cycles). This method is expected to improve the conductivity and capacitance for all-solid-state carbon-based fiber supercapacitor with good flexibility and light weight.

We present a facile and efficient route to introduce in-plane nanopores on the graphene sheets by activation of graphene aerogel (GA) with phosphoric acid (H3PO4). Results from N2 adsorption and TEM images showed that H3PO4 activation created mesopores with pore size of 2–8 nm on the graphene sheets. With such nanopores on graphene sheets, the activated GA exhibits a specific capacitance of 204 F g−1, enhanced rate capability (69% capacitance retention from 0.2 to 30 A g−1), reduced equivalent series resistance (3.8 mΩ) and shortened time constant (0.73 s) when comparing with the hydrothermally-derived pristine GA and thermally annealed GA in the absent of H3PO4. The excellent capacitive properties demonstrate that introduction of nanopores on GA by H3PO4 activation not only provides large ion-accessible surface area for efficient charge storage, but also promotes the kinetics of electrolyte across the graphene two-dimensional planes.

The layered structure stability of bulk vanadyl phosphate dihydrate (VOPO 4 ·2H 2 O) is investigated by using a deintercalation-intercalation reaction process involving short-range swelling, its basal spacing can be reversibility controlled and the layered structure can be maintained to above 400 °C. By using delaminated vanadyl phosphate (VOPO 4 ) nanosheets in 2-propanol, VOPO 4 /reduced graphene oxide (RGO) hybrid electrode materials for supercapacitor with different mass ratios of VOPO 4 nanosheets to graphene oxide (GO) nanosheets have been prepared based on a nanosheet reassembling reaction between the exfoliated VOPO 4 nanosheets and GO nanosheets and followed by calcinating in a tubular furnace at 400 °C for 3 h under N 2 atmosphere, and their electrochemical properties are systematically investigated by cyclic voltammetry and galvanostatic charge-discharge in 0.5 M K 2 SO 4 electrolyte. The VOPO 4 /RGO hybrid electrode with a mass ratio of VOPO 4 /RGO = 1 exhibits a high specific capacitance of 378 F g −1 at a scan rate of 5 mV s −1 with a good rate capability. This method broadens the application filed of VOPO 4 nanosheets, and also supplies promising electrode candidates for supercapacitor.

A facile yet effective chemical vapor deposition (CVD) method to prepare carbon nanomesh (CNM) with MgAl-layered double oxides (LDO) as sacrificial template and ferrocene as carbon precursor is reported. Due to the combined effect of the LDO template and organometallic precursor, the as-made hexagonal thin-sheet CNM features a hierarchical pore system consisting of micropores and small mesopores with a size range of 1–6 nm, and a great number of random large mesopores with a pore size of 10–50 nm. The density, geometry, and size of the pores are strongly dependent on the CVD time and the annealing conditions. As supercapacitor electrode, the CNM exhibits an enhanced capacitance, high rate capability, and outstanding cycling performance with a much-shortened time constant. The excellent capacitive performance is due to the presence of the large mesopores in the 2D CNM, which not only offer additional ion channels to accelerate the diffusion rate across the thin sheets but also help to make efficient use of the oxygen functional groups at the edges of large mesopores to increase the pseudocapacitance contribution.

Well-defined single crystal γ-MnOOH with novel hexagram morphology was prepared by hydrothermal treating a suspension of ethyl acetate and KMnO 4 at 200 °C for 48 h, and its formation process had been investigated on the basis of XRD, FESEM, TEM, HRTEM, and SAED analyses. In keeping hydrothermal treatment temperature and reaction time, ethyl acetate played an important role in controlling the crystal phase and morphology of the obtained materials, which was used as both reducing agent and etchant. It hydrolyzed into acetic acid and ethanol slowly and caused an acidic reaction environment accompanied with hydrothermal reaction. The acetic acid was adsorbed on the lateral of γ-MnOOH with multiple branched nanorods, which caused a soft etching process and the lateral of the multiple branched nanorods became sharper and thinner and finally transformed into γ-MnOOH with hexagram morphology. The prepared γ-MnOOH with novel hexagram morphology is expected to be used for a fundamental study in surface science and for potential applications such as adsorbent, electro-catalyst, sensing and so on.

Sandwich-like graphene/MnO2 nanosphere (RGO/MnO2 NS) hybrid film is assembled with graphene (RGO) nanosheets and MnO2 nanospheres (MnO2 NS) by a typical filtration-directed self-assembly method. The film structure and its electrode performance are systematically investigated. RGO nanosheets and MnO2 NS are well linked together and the MnO2 NS are uniformly embedded into the RGO matrix to form interactive laminated nanostructure, which offers ion pathways for fast electrolyte diffusion. The [RGO/MnO2]10 film electrode obtained with a mass ratio of RGO/MnO2 NS = 2 in each layer shows not only high specific capacitance of 446 F g−1 at 5 mV s−1, but also good cycling performance. After 1000 consecutive cycles with a scan rate of 20 mV s−1 in 1 M Na2SO4 electrolyte, its specific capacitance retains about 96% of its original capacitance. The good cycling performance is ascribed to the novel [RGO/MnO2]10 film nanostructure, which benefits the ion and charge transfer and keeps the average oxidation state of Mn unchange. This filtration-directed self-assembly method can also be used for the preparation of RGO and other metal oxide hybrid film electrodes with good capacitance.

Four nanostructured polyanilines (PANIs) with different morphologies, including nanofibers, nanoflowers, nanorods, and nanotubes are prepared by an adsorption–template technique in acidic condition. Manganese dioxides (α−MnO 2 ) with different morphologies are used as reactive templates as well as oxidants. The aniline monomers are adsorbed on the surface of α−MnO 2 templates and then they are turn into PANIs with novel morphologies. The preparation process of the PANIs with different morphologies is topochemical reaction, and the obtained PANIs with different morphologies show not only better dispersity, but also better uniformity in size. The electrochemical measurements show that their performance is highly dependent on the morphology of PANI electrodes. The specific capacitances of PANI electrodes are 521, 543, 638, and 661 F g −1 at a current density of 1 A g −1 for nanofibers, nanoflowers, nanorods, and nanotubes, respectively, and their capacitive retentions are about 50, 75, 70, and 88% as the current density increases from 1 to 10 A g −1 . The PANI nanotube electrode shows the highest specific capacitance and best rate performance due to its high conductivity and good ion transportation. This method may be readily extended to the preparation of other conducting polymers with good capacitive performance.

The birnessite-type layered manganese oxide nanoplates with good dispersity and regular hexagonal morphology were obtained by topochemical oxidizing precursor Mn(OH)2 in NaClO solution for 24 h at room temperature, and its formation process was systematically investigated on the basis of the XRD pattern, FESEM and TEM images, XPS, Raman spectra, and TG-DTA analysis. The research results showed that the obtained birnessite-type layered manganese oxide nanoplates inherited the layered structure and regular hexagonal morphology from their Mn(OH)2 precursor. The regular hexagonal nanoplates were about 150 nm in each lateral edge with a thickness of 120 nm, which were self-assembled from MnO2 particles. The dispersity and regular morphology of the obtained materials were affected by the precursor Mn(OH)2 and the oxidation reaction times. This intermediate-mediated topochemical oxidation method could contribute to the design of new kinds of metal oxide materials with novel morphology and potential application.

Graphite oxide/Co(OH) 2 layered composites are prepared by nanosheet assembling between the exfoliated Co(OH) 2 and graphene oxide (GO) nanosheets. The subsequent thermal treatment of GO/Co(OH) 2 composites in controlled atmospheres converts GO into reduced graphene oxide (RGO) and Co(OH) 2 into Co 3 O 4 . The RGO/Co 3 O 4 hybrid nanocomposites with different amounts of Co 3 O 4 are thoroughly characterized, and their electrochemical properties as supercapacitor electrode are systematically investigated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy in the KOH electrolyte. In particularly, the RGO/Co 3 O 4 hybrid composite with 94.3 wt% Co 3 O 4 exhibits a high specific capacitance of 331 F g −1 at the current density of 5 A g −1 , and shows the excellent electrochemical cycle stability with capacitance retention over 122% after 5000 continuous charge–discharge cycles. These outstanding capacitive performances make the RGO/Co 3 O 4 hybrid nanocomposites one of the promising candidates for the supercapacitor electrode.

Vanadium oxides have attracted significant attention for electrochemical capacitor because of their extensive multifunctional properties. In the present work, graphene/VO2 (RG/VO2) hybrid materials with different RG amounts are prepared in a mixture of ammonium vanadate, formic acid and graphite oxide (GO) nanosheets by one-step simultaneous hydrothermal reduction technology. The hydrothermal treatment makes the reduction of GO into RG and the formation of VO2 particles with starfruit morphology. The starfruit-like VO2 particles are uniformly embedded in the hole constructed by RG nanosheets, which makes the electrode–electrolyte contact better. A high specific capacitance of 225 F g−1 has been achieved for RG(1.0)/VO2 electrode with RG content of 26 wt% in 0.5 mol L−1 K2SO4 electrolyte. An asymmetrical electrochemical capacitor is assembled by using RG(1.0)/VO2 as positive electrode and RG as negative electrode, and it can be reversibly charged–discharged at a cell voltage of 1.7 V in 0.5 mol L−1 K2SO4 electrolyte. The asymmetrical capacitor can deliver an energy density of 22.8 Wh kg−1 at a power density of 425 W kg−1, much higher than those of the symmetrical electrochemical capacitor based on the RG and RG(1.0)/VO2 electrodes. Moreover, the asymmetrical capacitor preserves 81% of its initial capacitance over 1000 cycles at a current density of 5 A g−1.

We report a facile and green route to reduce graphite oxide using urea as the reducing agent. UV-Vis, XRD and XPS results revealed that urea was an effective reducing agent in removing oxygen-containing groups from graphite oxide for restoring the conjugated electronic structure of graphene. The obtained reduced graphene oxide was tested as supercapacitor electrode. Gravimetric capacitances of 255 and 100 F g−1 at current densities of 0.5 and 30 A g−1, respectively, were observed. The reduced graphene oxide paper showed a volumetric capacitance of 196 F cm−3. After 1200 continuous cycles of galvanostatic charge–discharge, the electrode retained 93% of its capacitance. The electrocapacitive performance of the urea-reduced graphene oxide outperformed most of the previously reported graphene-based electrode materials, which were reduced by hydrazine or NaBH4. The present reduction method holds great promise for mass production of soluble graphene-based materials for electrochemical energy storage.

Spherical colloidal particles with a hollow interior and a mesoporous shell are particularly useful for drug delivery and release because such spheres combine the unique properties of hollow interior (for storing the drug) with mesoporous shell (for controlled release). Hollow silica spheres (HSS) with a mesoporous shell were prepared via a sol–gel process in the presence of dual templates polystyrene spheres and cetyltrimethylammonium bromide for creating the hollow core and mesopore shell. The effect of the ratio of silica precursor over polystyrene spheres on particle morphology and pore structure of the HSS was investigated. The adsorption kinetics of methyl blue on the HSS was evaluated and correlated with the mesoporous shell structure.

Gold (Au) nanoparticles of sizes in the range of 2–4 nm dispersed on ordered mesoporous silica were prepared via a one-pot synthesis route in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). MPTMS was found to play a dual role: one was to coordinate the Au precursor ( AuCl 4 - ) via its thiol ligands and the other one was to form covalent bonds with the silica matrix. The interaction of the Au species with MPTMS was studied using real-time ultraviolet–visible spectroscopy and X-ray photoelectron spectroscopy techniques. The formation of Au (I)–thiolate complexes in the synthesis gel was identified and found to play a crucial role in the dispersion of the final Au nanoparticles on the support. The Au nanoparticles dispersed on the mesoporous silica exhibited high catalytic activity and selectivity in solvent-free selective oxidation of cyclohexane using molecular oxygen.

Hollow carbon spheres (HCS) with specific surface areas as high as 2239 m2/g were prepared by chemical vapor deposition with ferrocene as the carbon precursor and colloidal silica spheres as the template. Chemical oxidative polymerization of aniline in the presence of the HCS yielded composite materials with a layer of polyaniline (PANI) deposited on the external surface of the HCS. The electrocapacitive properties of the composite materials (HCS-PANI) with different PANI contents were evaluated using cyclic voltammetry, galvanostatic charge−discharge, and electrochemical impedance spectroscopy techniques. Results showed that the specific capacitances of the HCS before and after PANI coating were, respectively, 268 and 525 F/g in an aqueous H2SO4 electrolyte, which is almost doubly enhanced. A maximum energy density of 17.2 Wh/kg was achieved for the HCS-PANI electrode at a discharge current density of 0.1 A/g. However, the energy density of the HCS-PANI electrodes with higher PANI contents (>65 wt %) dec...

A novel graphitized ordered macroporous carbon (GMC, pore size approximately 380 nm) with hierarchical mesopores (2-30 nm) and high graphitization degree was prepared by nickel-catalyzed graphitization of polystyrene arrays. The obtained GMC possessed high specific surface area, large pore volume, and good electrical conductivity, which was explored for the enzyme entrapment and biosensor fabrication by a facile method. With advantages of novel nanostructure and good electrical conductivity, direct electrochemistry of hemoglobin (a model protein) was observed on the GMC-based biocomposite with a formal potential of -0.36 V (vs. Ag/AgCl) and an apparent heterogeneous electron transfer rate constant (k(s)) of 1.2 s(-1) in pH 7.0 buffer. Comparative studies revealed that GMC offered significant advantages over carbon nanotubes (CNTs) in facilitating direct electron transfer of entrapped Hb. The fabricated biosensor exhibited good sensitivity (101.6 mA cm(-2) M(-1)) and reproducibility, wide linear range (1-267 microM), low detection limit (0.1 microM), and good long-term stability for H(2)O(2) detection. GMC proved to be a promising matrix for enzyme entrapment and biosensor fabrication, and may find wide potential applications in biomedical detection and environmental analyses.

Fe/SBA-15/carbon composites were synthesized by chemical vapor infiltration (CVI) method using ferrocene as concurrent iron and carbon precursor. Accordingly, Fe2O3 nanoparticles supported on mesoporous SBA-15 silica or metallic Fe homogeneously embedded in mesoporous carbon were selectively obtained either by oxidizing the carbon component in air or by removing the silica template using an aqueous NaOH solution. The Fe2O3/SBA-15 and Fe/carbon composites so obtained were thoroughly characterized by N-2 adsorption/desorption isotherm measurements, powder X-ray diffraction (XRD), transmission electron microscopy and H-2-temperature programmed reduction (H-2-TPR). The effects of CVI duration time and temperature on their corresponding reduction states and particle dispersion, and consequently on their catalytic performances during benzylation reaction of benzene with benzyl chloride were examined and discussed. (C) 2009 Elsevier Inc. All rights reserved.

H 2 with ultra-low CO concentration was produced via photocatalytic reforming of methanol on Au / TiO 2 catalyst. The rate of H 2 production is greatly increased when the gold particle size is reduced from 10 to smaller than 3 nm. The concentration of CO in H 2 decreases with reducing the gold particle size of the catalyst. It is suggested that the by-product CO is mostly produced via decomposition of the intermediate formic acid species derived from methanol. The smaller gold particles possibly switch the HCOOH decomposition reaction mainly to H 2 and CO 2 products while suppress the CO and H 2 O products. In addition, some CO may be oxidized to CO 2 by photogenerated oxidizing species at the perimeter interface between the small gold particles and TiO 2 under photocatalytic condition.

A novel and effective method was described in this work to prepare two-dimensional hexagonally ordered mesoporous CMK-5 carbon materials. This method is based on the chemical vapor deposition (CVD) of ferrocene in the mesopores of SBA-15 at 500 °C, followed by graphitization at different temperatures. Both the silica/carbon composite and the resulting CMK-5 were characterized by N2 adsorption, powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), and thermogravimetric analysis. It was found that the ferrocene could be used as a new precursor to prepare CMK-5 nanopipes, with pipe thicknesses varying from 0.8 to 2.6 nm, by increasing the CVD time from 20 to 120 min. The resulting CMK-5 exhibits high Brunauer−Emmett−Teller (BET) surface area (1044−2449 m2/g) and large pore volume (1.13−2.20 cm3/g). The graphitization degree of the resulting CMK-5 was investigated by pyrolyzing the corresponding silica/carbon composite at diff...

Mesoporous graphitic carbon with high surface area (298.2 m 2 /g) was fabricated at 950°C using monodisperse colloid SiO 2 with diameter of 26 nm as the template, styrene as the carbon precursor, and Ni as the catalyst. The obtained carbon material was characterized by powder X-ray diffraction, N 2 adsorption, thermogravimetric analysis, and transmission electron microscopy. The presence of Ni was crucial to the formation of graphitized mesoporous carbon. The TiO 2 /graphitic carbon composite was prepared by loading TiO 2 in the mesopores of the graphitic carbon via the sol-gel method. Both the surface area and pore volume of the composite were significantly reduced in contrast to the mesoporous graphitic carbon. The photoactivity of TiO 2 /graphitic carbon was investigated by photocatalytic degradation aqueous solutions of rhodamine B and phenol. The degradation of both rhodamine B and phenol followed first-order reaction kinetics, and the composite showed higher photoactivity than the pure anatase TiO 2 .

By using three-dimensional (3D) tubular molybdenum disulfide (MoS2) as both an active material in electrochemical reaction and a framework to provide more paths for insertion and extraction of ions, PANI nanowire arrays with a diameter of 10-20 nm can be controllably grown on both the external and internal surface of 3D tubular MoS2 by in situ oxidative polymerization of aniline monomers and 3D tubular MoS2/PANI hybrid materials with different amounts of PANI are prepared. A controllable growth of PANI nanowire arrays on the tubular MoS2 surface provides an opportunity to optimize the capacitive performance of the obtained electrodes. When the loading amount of PANI is 60%, the obtained MoS2/PANI-60 hybrid electrode not only shows a high specific capacitance of 552 F/g at a current density of 0.5 A/g, but also gives excellent rate capability of 82% from 0.5 to 30 A/g. The remarkable rate performance can be mainly attributed to the architecture with synergistic effect between 3D tubular MoS2 and PANI nanowire arrays. Moreover, the MoS2/PANI-60 based symmetric supercapacitor also exhibits the excellent rate performance and good cycling stability. The specific capacitance based on the total mass of the two electrodes is 124 F/g at a current density of 1 A/g and 79% of its initial capacitance is remained after 6000 cycles. The 3D tubular structure provides a good and favorable method for improving the capacitance retention of PANI electrode.

Sulfur-substituted In(OH)(3) [hereafter denoted as In(OH)(y)S-z] and Zn-doped In(OH)(y)S-z [hereafter denoted as In(OH)(y)S-z:Zn] are synthesized in an aqueous Solution of ethylenediamine via the hydrothermal method. The photoactivities of these catalysts for H,) production are investigated in the presence of Na2S and Na2SO3 sacrificial reagent under visible light illumination (lambda > 420 nm). The absorption edge of In(OH)(y)S-z shifted monotonically from 240 nm for In(OH)(3) to 570 nm for In(OH)(y)S-z when the atomic ratio of S/In in the synthesis solution is increased from 0 to 2.0. But the absorption edge of In(OH)(y)S-z:Zn shifted from 570 to 470 nm as the atomic ratio of Zn/In in the synthesis solution was increased from 0 to 1.0. The catalyst In(OH)(y)S-z is active for H-2 production, with an average rate of H-2 of 0.9-1.8 mu mol/h, under visible light illumination. The The rate of H-2 production is 35.8 and 67 mu mol/h on 2wt% Pt-loaded In(OH)(y)S-z:Zn photoactivity of In(OH)(y)S-z is enhanced by doping with Zn2+ catalyst when X = 0.2 and 0.5, respectively, corresponding to a quantum efficiency of 0.32 and 0.59% at 420 +/- 10 nm, respectively. (c) 2005 Elsevier Inc. All rights reserved.

A high-performance supercapacitor electrode consisting of platelet ordered mesoporous carbon CMK-5 and polyaniline (PANi) was prepared by chemical oxidative polymerization of aniline in the presence of CMK-5. The PANi with uniform size of 2-5 nm was primarily confined in the mesochannels of CMK-5 at low PANi loadings (40 and 51 wt %), whereas at a high loading of 64 wt %, additional PANi thin films with thicknesses of 5-10 nm were coated on the surface of the CMK-5 particles. Such CMK-5-PANi composites afforded a high electrochemical active surface area for surface Faradic redox reactions, leading to a more than 50% utilization efficiency when considering the theoretical capacitance of PANi of about 2000 F/g. As a result, a specific capacitance of 803 F/g and an energy density of 27.4 Wh/kg were achieved for CMK-5-PANi composite electrode with 64 wt % PANi, showing substantial improvement as compared with symmetric capacitors configured with CMK-5 electrodes (10.1 Wh/kg) or pure PANi electrodes (16.4 Wh/kg). Moreover, an excellent rate capability and a substantially enhanced electrochemical stability with 81% capacitance retention as compared with 68% of pure PANi were also observed over 1000 charge-discharge cycles at a constant current density of 4.0 A/g.

Ordered macroporous lanthanide oxides (Eu2O3, Nd2O3 and Sm2O3) have been fabricated using colloidal crystals of polystyrene (PS) spheres as a template in conjunction with the sol–gel method. Solidification of Ln3+–EDTA chelates in the voids between the PS spheres and removal of the template by calcination yields three-dimensional ordered macroporous oxides. X-Ray diffraction reveals that the phases of Eu2O3 , Nd2O3 and Sm2O3 are cubic, hexagonal and cubic, respectively, and scanning electron micrography shows that these oxides retain the structure of the initial template and exhibit 3D long-range ordered close packing of pores. The properties of these oxides are expected to allow them to find applications in areas including separation, catalysis and photonic crystals.