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Molybdenum disulfide (MoS2) has been extensively studied as a potential storage material for batteries. However, the electrochemical performance of MoS2 is far from ideal, and it exhibits severe activity fading resulting from its low electronic conductivity. The present work synthesizes nitrogen (N)-doped 1T MoS2 nanoflowers made of ultrathin nanosheets via the one-step hydrothermal sulfurization of a molybdenum-based metal-organic framework precursor. The resulting metallic phase shows improved conductivity and hydrophilicity, and characterization demonstrates that N doping effectively expands the interlayer spacing and increases the concentration of sulfur vacancies serving as defects. This material demonstrates high rate performance and good cycling stability when used as the cathode in an aqueous rechargeable zinc-ion battery (ARZIB). Its performance is superior to those of pure 1T MoS2 and 2H MoS2 synthesized with MoO3 as the molybdenum source. Ex situ X-ray photoelectron spectroscopy and X-ray diffraction analyses are performed to explore the reaction mechanism during charging and discharging of the N-doped 1T MoS2. A three-cell series ARZIB system containing this material is used to power five light-emitting diodes to confirm the possible practical applications of this technology.

The all-inorganic CsPb(IxBr1-x)3 (0 ≤ x ≤ 1) perovskite solar cells (PSCs) are attractive by virtue of their high environmental and thermal stability. Nevertheless, multiple-step deposition and high annealing temperature (>250 °C) and the structural and optoelectronic properties changes upon temperature-dependent phase-transition are potential impediments for highly efficient and stable PSCs. Herein, a space-confined method to fabricate stable lower-order symmetric pure monoclinic CsPbBr3 phase at low temperature (

This study presents a straightforward approach for the in situ polymerization of poly(N-isopropylacrylamide) (PNIPAM) chains within the one-dimensional (1D) pores of the five-coordinated zinc-based metal–organic framework DMOF in order to obtain new MOF-based composites. The loading amount of PNIPAM within DMOF ⊃ PNIPAM composites can be tuned by changing the initial weight ratio between NIPAM, which is the monomer of PNIPAM, and DMOF. The guest PNIPAM chains in the composites block partially the 1D pores of DMOF, thus leading to a narrowed nanospace. The water adsorption studies reveal that the water uptake increased by increasing the loading of PNIPAM in the final DMOF ⊃ PNIPAM composites, indicating that the exposed amide groups of PNIPAM gradually alter the hydrophobicity of pristine DMOF and lead to hydrophilic DMOF ⊃ PNIPAM composites. The composite with the highest loading of PNIPAM displays a selective adsorption for water and methanol over ethanol when using equimolar mixtures of methanol–ethanol and water–ethanol. This is confirmed by the single-component adsorption measurements as well as ideal adsorbed solution theory molecular simulations. Additionally, the water stability of pristine DMOF has been greatly improved after the incorporation of PNIPAM in its pores. PNIPAM can undergo a phase transition between hydrophobic and hydrophilic phases in response to a low temperature change. This property is used in order to control the desorption of water and methanol molecules, thus enabling an efficient and cost-effective regeneration process.

This work reports a new approach for the synthesis of a zeolitic imidazolate framework (ZIF-8) composite. It employs the direct growth of the crystalline ZIF-8 on a mixed-metal oxide support TiO2 -SiO2(TSO), which mimics the porous structure of Populus nigra. Using the natural leaf as a template, the TSO support was prepared using a sol-gel method. The growth of the ZIF-8 layer on the TSO support was carried out by the seeds and second growth method. This method facilitates the homogeneous dispersion of ZIF-8 crystals at the surface of the TSO composite. The ZIF-8@TSO composite adsorbs methanol selectively, mainly due to the hierarchical porous structure of the mixed oxide support. As compared with the as-synthesized ZIF-8, a 50% methanol uptake is achieved in the ZIF-8@TSO composite, with only 25 wt % ZIF-8 loading. LAST simulations show that the ZIF-8@TSO composite has a preferential adsorption toward methanol when using an equimolar methanol-ethanol mixture. An opposite behavior is observed for the as-synthesized ZIF-8. The results show that combining MOFs and mixed-oxide supports with bioinspired structures opens opportunities for synthesizing new materials with unique and enhanced adsorption and separation properties.

Graphene-based materials have potential applications in supercapacitors, owing to their unique two-dimensional structure, high surface area, remarkable chemical stability, and outstanding electrical conductivity. In this work, Hummers method was used to prepare graphene oxide, and then in situ electrochemical method was firstly used to deposit graphene nanosheets on Co/CoO core-shell nano-structure to form a sandwich-type of Co/CoO/graphene electrode materials. The effect of electro-deposition graphene cycles on the electrochemical properties of Co/CoO/graphene composite were investigated. The results showed that the coating of graphene on Co/CoO further enhanced the conductivity of the material, and the specific capacitance reached 7.765 F cm−2 at the current density of 1 mA cm−2. The Co/CoO/graphene and AC were assembled into an asymmetric supercapacitor. After 10000 charge/discharge cycles, the total capacitance of the asymmetric supercapacitor was still maintained 79.9%. The coating of graphene not only increased the conductivity of the material, but also increased the stable of structure.

Defects caused by the structural disorder of perovskites and voltage loss resulting from mismatched band structure are important issues to address to improve the performance of carbon-based perovskite solar cells. Different from the conventional approaches of additive-based passivation of perovskite precursors and introducing a hole-transport layer between the perovskite layer and carbon electrode, herein we report a defect-healing method using phenethyl ammonium iodide (PEAI) treatment and band-structure modification using high-work-function inorganic copper phthalocyanine (CuPc). Because of its relatively smoother surfaces and lower defect content, the optimized device after PEAI-based passivation of the perovskite achieves a power conversion efficiency (PCE) of 11.74%. The PCE is further raised to 13.41% through the auxiliary energy-level matching and high hole extraction abilities of the CuPc-modified carbon electrode. The best-performing device exhibits excellent moisture tolerance and thermal stability with minor current density–voltage hysteresis.

A low-temperature carbon electrode with good perovskite compatibility is employed in hole-transport-material free perovskite solar cells, and a champion power conversion efficiency (PCE) of 11.7% is obtained. The PCE is enhanced to 14.55% by an interface modification of PEDOT:PSS. The application of this carbon on ITO/PEN substrates is also demonstrated.

It is a highly desirable but still a challenging task to find a simple, fast and straightforward method to greatly improve the electrochemical properties of a Co3O4 electrode for pseudocapacitors. In this study, we demonstrate that developing an amorphous Co–phosphate (Co–Pi) shell via in situ surface derivatization on a Co3O4 nanowire (NW) surface facilitates the diffusion and reaction of electrolyte ions and leads to distinctive conductivity. Because of these advantages, 1D nanostructures and the synergistic effect between Co3O4 and amorphous Co–Pi, the resulting core–shell Co3O4@Co–Pi nanowire (NW) array exhibits high capacitance (1692 F g−1 at current density of 1 A g−1). In addition, high rate capabilities and retention capacity of 86% after 6000 cycles at 20 A g−1 are achieved. By using the Co3O4@Co–Pi core–shell hybrid NW array and activated carbon as the anode and cathode, respectively, asymmetric pseudocapacitors are assembled that exhibit high capacitance (energy density of 35.69 W h kg−1 at power density of 558 W kg−1) and super-long cycle life (82% capacitance retention after 40 000 cycles). Our synthesis method provides a new technology for the design of composites of transition metal oxides/hydroxides and phosphates for electrochemical energy storage applications.

Transition metal oxides as the electrode material of supercapacitors have been widely studied due to their high energy density. However, relatively low power density resulting from poor conductivity of the metal oxides limits their application. In this paper, a new N-doped NiCoO2 nanosheet array on Ni foam was synthesized through an ammonia-induced reduction strategy. During the ventilation of NH3 in the ammonia annealing stage, N was doped into the structure of NiCoO2, which leads to increased concentration of oxygen vacancies and improved conductivity. As a positive electrode, N-doped NiCoO2 exhibits excellent rate performance (1449.3 F g−1 at 1 A g−1 and 1190.4 F g−1 at 50 A g−1) and impressive cycle stability (the capacitance retention ratio is 92% after 5000 cycles at the current density of 40 A g−1) compared to undoped NiCoO2 nanosheet array electrode. Assembling it as the positive electrode and activated carbon as the negative electrode, the aqueous asymmetric supercapacitor exhibits high power density, energy density, and excellent rate performance. The remarkable energy storage performances make N-doped NiCoO2 nanosheet arrays material (N-NiCoO2) have a broad application prospect in the field of supercapacitors.

In this work, we report on the use of hydrothermal and hydrogenation processes to synthesize oxygen-deficient NiMoO4 nanoflake arrays (OD-NF) and nanowire arrays (OD-NW) for electrode applications. The introduction of oxygen vacancies into NiMoO4 increased the interlayer spacing of the crystal structure and Mo6+ in NiMoO4 was partially reduced to Mo4+. In addition to increasing the conductivity, the oxygen vacancies also promoted charge storage kinetics, while retaining the crystal structure of NiMoO4. The oxygen vacancies considerably influenced the capacitive performance of NiMoO4. Notably, OD-NF showed better electrochemical performance than that of OD-NW. Furthermore, our asymmetric supercapacitor device composed of NiMoO4 OD-NF and active carbon achieved 49.1 Wh kg−1 at a power density of 800 W kg−1 and retained a remarkable 94.2% specific capacitance after 6000 cycles.

It remains a challenge to develop simple and mild strategies for synthesizing various Co(OH)2 nanostructures on substrates. Inspired by semipermeable membranes, a Celgard membrane was used as an interface for separating components of the precursor solution and for ion exchange, to construct hierarchical Co(OH)2 nanostructures. In contrast to traditional solvothermal reactions, this Celgard membrane-based method is simple and effective for preparing high-loading Co(OH)2 array (density of approximately 7 mg cm−2) on Ni foam. The permeability of the Celgard membrane was affected by the presence of an organic solvent. The morphology of Co(OH)2 could be adjusted by controlling the OH− diffusion rate across the Celgard membrane. OH− was formed via the hydrolysis of urea solution. The optimized Co(OH)2 nanosheet electrode exhibited a specific capacitance of 2406 F g−1 at 1 A g−1, and good cycling stability (89.1% capacitance retention after 5000 cycles) in 2 M aqueous KOH aqueous solution, using a typical three-electrode cell. An asymmetric supercapacitor was assembled with a Co(OH)2 nanosheet array as the positive electrode, and activated carbon as the negative electrode. The asymmetric supercapacitor exhibited a high energy density (39.2 W h kg−1), high power density (9.2 kW kg−1 at 28.9 W h kg−1), and excellent cycling stability (84.2% capacitance retention after 10,000 cycles).

β-Ni(OH)2 is considered a potential candidate of supercapacitor electrode material due to its high theoretical capacitance and cost efficiency. In order for β-Ni(OH)2 electrode to achieve high areal capacitances, we report effective fabrication of high mass loading low-crystalline β-Ni(OH)2 on nickel foam through the acid-etching formation of Ni3(PO4)2 precursor and the subsequent electrochemical activation. The heavily-loaded (13.5 mg cm−2), binder-free β-Ni(OH)2 electrode presents a high areal capacitance of 15.31F cm−2 (1134F g−1) at current density of 30 mA cm−2 (2.22 A g−1) and has a capacitance retention of 85% after 10,000 cycles at a high current density of 110 mA cm−2 (7.41 A g−1). Besides, the assembled hybrid supercapacitors can deliver an areal capacitance of 2.59F cm−2 at 20 mA cm−2 with a maximum energy density of 0.49 mWh cm−2 (2.45 mWh cm−3). This work provides a certain reference for exploring a low-cost and large-scale method of material synthesis at room temperature for high mass loading and capacitance in the future application.

ZnCo2O4 possess a high theoretical specific capacity, but low conductivity, poor stability and short cycle life hinder its practical application. In order to overcome those disadvantages of ZnCo2O4, herein, porous ZnCo2O4/Carbon (ZnCo2O4/C) core-shell nanowire arrays (NWAs) grown on Ni foam was synthesized by simple hydrothermal method and followed chemical vapor deposition. Compared with the pure ZnCo2O4, deposition of carbon offers an opportunity to significantly improve the conductivity, stability, and electrochemical performance of ZnCo2O4 NWAs. The ZnCo2O4/C electrodes deliver a high areal capacitance of 7.02 F cm−2 (2340 F g−1) and superior cycling stability of 92.6% after 10,000 cycles at 20 mA cm−2. Moreover, an asymmetric supercapacitor (ASC) was assembled with ZnCo2O4/C NWAs as the positive electrode and activated carbon (AC) as the negative electrode. The ASC device shows a high energy density of 35.75 Wh kg−1 at a power density of 73.17 W kg−1 and 73.3% of capacitance retention over 10,000 cycles. In brief, the ZnCo2O4/C NWAs are expected to be a promising material for energy storage devices of high-performance supercapacitor.

The TiO 2 nanotubes (TNT) are synthesized and decorated with Au nanoparticles, forming a TNT-Au composite. This TNT-Au composite is incorporated into a TiO 2 nanocrystalline film to form a multifunctional composite photoanode and the dye-sensitized solar cell (DSSC). The influences of different amounts of TNT-Au on the performance of the multifunctional composite photoanodes and DSSCs are investigated. Studies indicate that, the introduction of TNT-Au improves remarkably the transport rate of electrons, enhances the ability of photoanode to scatter and capture incident light, reduces the charge transfer resistance, and thereby improves significantly the short-circuit current density (J sc ) and photoelectric conversion efficiency (PCE) of the DSSCs. The maximal J sc of 14.72 mA cm −2 and PCE of 6.94% are obtained in the optimal DSSC with 10 wt% TNT-Au, significantly higher than those of the DSSC with pure TiO 2 photoanode by 24.3% and 21.8%, respectively. These remarkable improvement in the properties of the DSSCs can be attributed to the strong scattering of TNT for incident light, fast charge transfer of TNT due to their unique one dimensional hollow structure, and the surface plasmon resonance of Au nanoparticles, in a tri-synergistic and complementary fashion.

It is of great significance to develop a simple, cheap, and efficient catalyst preparation method for the development of fuel cells. Despite considerable developmental efforts have been substantial, progress has been underwhelming. To this end, a simple one-pot approach has been designed for the fabrication of Pd–Ag alloy networks (NWs) catalysts using sodium borohydride (NaBH4) as the reducing agent and cetyltrimethylammonium bromide (CTAB) as the surfactant. The electrochemical results reveal that the addition of Ag not only reduces Pd consumption but also enhances the catalytic properties of the electrocatalysts. Particularly, the current density of a Pd2Ag1 NWs-catalyzed ethylene glycol electro-oxidation reaches 1902.9 mA mg−1, which is 1.40 times higher than that for commercial Pd/C. The catalyst’s impressive performance could be attributed to its distinctive network-like structure and the promoting effect of Ag, which is in agreement with the bi-functional mechanism and a d-band electronic structure. This work is expected to have an impact for optimization of the design of high-performance Pd-based catalysts for applications in fuel cells and in the related fields.

Interstitial (Li) and substitutional-type (Mo) co-doped new-type urchin-like Lix(Mo0.3V0.7)2O5 (LMVO) is fabricated via in situ gas bubble template strategy, which leads to distinctive conductivity, high number of active sites, reversible ion intercalation and accessible redox couple. Consequently, the electrochemical performance of LMVO is enhanced enormously owing to the hollow morphology and unique electronic structure. The charge storage capability of the synthetic LMVO is investigated in Mg2+ and Zn2+ electrolytes as well as Li+ electrolyte, due to the similar radius, higher charge, abundant reserve and rational cost. As a result, LMVO achieves a specific capacitance of 484 F g−1 at 1 A g−1 in Zn2+ electrolyte, which apparently surpasses the performance in Li+ and Mg2+ electrolytes. Moreover, the assembled LMVO//LMVO device delivers a specific capacitance of 117 F g−1 at 0.8 A g−1, which indicates large potential for application.

A novel chemical successive ionic layer adsorption and reaction (SILAR) method has been used for the synthesis of hierarchical nanostructured material by growing Cu 2 O-Mn 3 O 4 nanoflakes onto TiO 2 crumpled micro-nano spheres, which were prepared by hydrothermal method on Ti foil substrate. The nanocomposites of TiO 2 /Cu 2 O-Mn 3 O 4 are strategically combined into a single entity to synergize and construct a high electrochemical performance of pseudocapacitor electrode. Specific capacitance of the ternary composite electrode achieves as high as 259 F g −1 at a current density of 3 A g −1 , when cycling performance (no capacity loss over 5000 cycles) is much better than that of TiO 2 /Mn 3 O 4 , TiO 2 /Cu 2 O and individual component Mn 3 O 4 electrodes.

Creating a hybrid cobaltous-based oxide/sulfide core-shell composite is an effective strategy to improve the composites conductivity thus enhance the electrochemical performance of cobaltous oxide. By using Co3O4 nanosheets (NSs) as precursor, a room-temperature sulfurization for obtaining Co3O4/CoS core-shell NSs via anion exchange is developed which show better supercapacitor performance in contrast to the most high-temperature material process required in synthesis of CoS. The study demonstrates that the preceding step of introducing oxygen vacancies to Co3O4 by NaBH4 solution reduction is crucial, which allows S2− to facilitate entering the position of O2− in the solid phase successfully at room temperature. The as-obtained Co3O4/CoS NSs preserve the porous morphology and have larger accessible active surface area and better conductivity than those of Co3O4 and CoS composite. In this report, the Co3O4/CoS NSs exhibit an improved specific capacitance of 1658 F g−1 at 1 A g−1 which can be maintained at 92.3% after 10,000 cycles. The corresponding assembled asymmetric supercapacitor with activated carbon as anode displays a high energy density of 23.6 Wh kg−1 at a power density of 250 W kg−1.

NiCo2S4 and carbon-NiCo2S4 hetero-structured nanosheet arrays have been firstly synthesized on nickel foams in a facile hydrothermal and CVD method. The products NiCo2S4 and carbon-NiCo2S4 are obtained in Na2S aqueous solution in a hydrothermal reaction from precursor of NiCox(OH)y and carbon-NiCo2O4 through anion exchange respectively, which are characterized by XRD, TEM, Raman analysis. The obtained binary metal sulphide NiCo2S4 nanosheet delivers better electrochemical activity and higher mass loading compared with NiCo2O4. In addition, carbon introduced enhances the capacitive behaviours and cycle performance for enhanced electric conductivity and stable architecture. The integrated carbon-NiCo2S4 electrode exhibits high areal capacitance of 8.33 F cm−2 and ultrahigh specific capacitance of 1893.2 F g−1 with a potential window of 0.8 V and high mass loading of 4.4 mg cm−2 and good cycle performance in a three-electrode system. The asymmetric supercapacitor is further assembled using carbon-NiCo2S4 as the positive electrode and activated carbon as the negative electrode. The integrated asymmetric supercapacitor demonstrates a high energy density of 68.82 Wh kg−1 at a power density of 47.83 W kg−1, which confirms its practical applicability.

We demonstrate a general method for the synthesis of biomass-derived hierarchical porous CdS/M/TiO 2 (M = Au, Ag, Pt, Pd) ternary heterojunctions for efficient photocatalytic hydrogen evolution. A typical biomass—wood are used as the raw sources while five species of wood ( Fir, Ash, White Pine, Lauan and Shiraki ) are chosen as templates for the synthesis of hierarchical porous TiO 2 . The as-obtained products inherited the hierarchical porous features with pores ranging from micrometers to nanometers, with improved photocatalytic hydrogen evolution activity than non-templated counterparts. Noble metals M (M = Pt, Au, Ag, Pd) and CdS are loaded via a two-step photodeposition method to form core (metal)/shell (CdS) structures. The photocatalytic modules—CdS(shell)/metal (core)/TiO 2 heterostructures, have demonstrated to increase visible light harvesting significantly and to increase the photocatalytic hydrogen evolution activity. The H 2 evolution rates of CdS/Pd/TiO 2 ternary heterostructures are about 6.7 times of CdS/TiO 2 binary heterojunctions and 4 times higher than Pd/CdS/TiO 2 due to the vertical electron transfer process. The design of such system is beneficial for enhanced activity from morphology control and composition adjustment, which would provide some new pathways for the design of promising photocatalytic systems for enhanced performance.

In this work, we report the synthesis of hybrid nanowire arrays by growing highly conductive carbon onto rough CoO nanowire arrays on 3D nickel foam. The CoO@C nanostructure arrays (CCNAs) are obtained via a hydrothermal method, followed by controlling the annealing and carbon deposition process at a relatively low temperature in the chemical vapor deposition (CVD) stage. In the carbon shell, apart from partial amorphous carbon, crystalline carbon was observed via TEM. With deposited carbon, the electrical conductivity and capacitance behaviors are dramatically promoted. The growth mechanism is proposed by TEM and XPS analyses, which firstly indicates that CoO could catalyze the decomposition of C2H2 at the low temperature of 427 °C in a reduction and catalytic process. The obtained CCNAs with a more hydrophilic surface and low resistance are tested as the working electrodes of supercapacitors, which lead to an ultrahigh specific capacitance of 3282.2 F g−1 approaching to the theoretical value. Good rate capability and 96.9% capacitance retention after 10 000 cycles suggest that such hybrid electrode possesses a great potential application. After assembling it as the positive electrode and activated carbon as the negative electrode, the aqueous asymmetric supercapacitor demonstrates an energy density value up to ∼58.9 W h kg−1 which is the highest value achieved among the Co-based supercapacitors.

This paper reports a new two-step approach for growing hybrid Ni(OH) 2 /graphene structure on nickel foam for the first time. Firstly, graphene was synthesized on nickel foam, which was used both as catalyst and template, by a CVD method. Then the three-dimensional network structured Ni(OH) 2 nanosheets were deposited on the graphene-coated nickel foam by a hydrothermal method. Electrochemical tests of this kind of electrode show a high specific capacitance (1440 F/g) and excellent cycling performance of ∼100% capacitance retention over 2000 cycles in a 1 M NaOH electrolyte. The presence of the graphene is critical to the high-performance of the electrode, and the experiment using the Ni(OH) 2 on bare nickel foam exhibited a much worse cycling performance.

A three dimensional (3D) porous framework-like N-doped carbon (PFNC) with a high specific surface area was successfully fabricated through ammonia doping and graphitization based on pomelo peel. The obtained PFNC exhibits an enhanced specific capacitance (260 F g(-1) at 1 A g(-1)) and superior cycling performance (capacitance retention of 84.2% after 10000 cycles at 10 A g(-1)) on account of numerous voids and pores which supply sufficient pathways for ion diffusion during cycling. Furthermore, a fabricated asymmetric PFNC//PFN device based on PFNC and porous flake-like NiO (PFN) arrays achieves a specific capacitance of 88.8 F g(-1) at 0.4 A g(-1) and an energy density of 27.75 Wh kg(-1) at a power density of 300 W kg(-1) and still retains 44 F g(-1) at 10 A g(-1) and 13.75 Wh kg(-1) at power density of 7500 W kg(-1). It is important that the device is able to supply two light-emitting diodes for 25 min, which demonstrates great application potential.

Arrays of novel ultralong nanoporous ZnO nanobelts (NBs) are developed with a two-step synthesis strategy. This strategy combines two processes, a rapid hydrothermal synthesis of vertically aligned ultralong Zn(OH)F NB arrays directly on fluorine-doped tin oxide (FTO) at pH = 8.5 and conversion of a pyrolysis Zn(OH)F NB intermediate into nanoporous ZnO NB. Two factors play crucial roles in the rapid synthesis of ultralong Zn(OH)F nanobelt (NB) arrays, i.e., the pretreatment of the FTO substrate before entering the aqueous solution of Zn 2+ (2 M) and the presence of excess F − in the hydrothermal reaction solution. Upon the subsequent pyrolysis of the Zn(OH)F precursor at 500 °C for 2 h, ultralong nanoporous ZnO NB arrays are successfully generated. In addition, every NB is composed of a large number of nanocrystals and nanopores, which exhibit preferred orientation. Dye-sensitized solar cells (DSSCs) based on the ultralong porous ZnO NB arrays are assembled, and a high conversion efficiency ( η ) of 3.28% for a 27 μm thick film is obtained at 0.9 suns. This can be attributed to the high internal surface area and pronounced light scattering, as well as a good electron collection efficiency comparable with that of ZnO nanorod (NR)-based DSSCs.

High yield of β-Ni(OH)2 was synthesized by hydrothermal reaction. After heat treatment, novel NiO nanosheets with hexagonal nanopores were obtained. Transmission electron microscopy was employed to investigate the morphology and the crystallographic structure of the products, which indicated that the nanosheets were commonly ⟨111⟩ orientated and the nanopores were bounded by {111} and {100} planes. Meanwhile, the nanosheets were oxygen-sufficient based on the electron energy loss spectroscopy. The mechanism associated with formation of the hexagonal nanopores was discussed according to structural evolution. This unique morphology and the chemical characteristics were considered as the probable key factor responsible for its excellent performance on catalysis, gas sense, and adsorption.

In the present work, high surface area mesoporous cobalt oxide (Co 3 O 4 ) nanobelts have been synthesized by thermal treatment of cobalt hydroxide carbonate (CHC) precursors. CHC nanobelts were prepared by a facile hydrothermal method. Control experiments with variations in reaction time, solvent and different cobalt source revealed that temperature and sulfates are key factors in determining the formation of CHC nanobelts. Scanning electron microscopy and transmission electron microscopy images showed that the Co 3 O 4 nanobelts consisted of mesoporous nanobelts with the average width of 40 nm. Brunauer–Emmett–Teller (BET) gas adsorption measurement further indicated that the products presented a rather large surface area (172.09 m 2 g −1 ).

A photoanode with a mesoporous F-doped ZnO prism array (F-ZnO PA) is prepared on an F-SnO 2 (FTO) glass substrate and its application in a dye-sensitized solar cell (DSSC) is investigated. A superstructure of mesoporous F-ZnO PA is obtained by thermal treatment of ZnF(OH) PA precursor, which has been previously grown directly onto the FTO substrate via chemical bath deposition. The structure and morphology of the films are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and TEM-EDS elemental mapping. The ZnO prisms are homogenously doped by F and composed of oriented nanograins and nanopores. Owing to the higher surface area and stronger light scattering, as well as longer electron lifetime and lower charge-transfer resistance, an electrical energy conversion efficiency ( η ) of 3.43% is achieved for a DSSC containing a 5 μm thick mesoporous F-ZnO PA photoanode, which is much higher than that for a similar cell based on a ZnO nanorod photoanode. The knowledge acquired in this work is important for the design of efficient photoanode materials for DSSCs.

In this study, ZnO nanotube and nanorod array films were respectively synthesized directly on F-doped SnO2 glass substrate (FTO) using a direct electrodeposition from a simple aqueous zinc salt solution. The effects of potential value, electrodeposition mode and solution stirring speed on the product morphology were investigated. Controlling the reaction under potentiostatic condition of −0.7 V at stirring speed of 300 r/min, large-scale nanotube arrays perpendicular to the substrate can be synthesized at a low temperature of 70 °C. By varying the reaction parameters, we can also obtain ZnO nanorod arrays. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy have been provided to characterize the structure and morphology of the nanotube and nanorod arrays. Experiment results show that the as-obtained ZnO has a single crystalline structure and c-axis oriented direction. The room-temperature photoluminescence spectrum of the ZnO nanotube array film displayed its high crystal property available as a photonic material. Electrodeposition is an effective method to prepare ZnO nanotube array films in quantity.

One-dimensional SrSn(OH) 6 nanowires were successfully synthesized through a rapid simple method-sonochemical synthesis at room temperature without using any templates or surfactants. The growth mechanism has been proposed, and the reaction conditions were carefully investigated. The experimental results revealed that both the ultrasound irradiation and the presence of Na 2 CO 3 in the synthetic process had an impact on the fast formation of the SrSn(OH) 6 nanowires. Moreover, a subsequent precipitation-hydrothermal treatment of SrSn(OH) 6 nanowires-was conducted in ethanol at 180 °C for 8 h in order to improve their crystallinity and thermal stalibity. SrSnO 3 nanorods were converted by calcination of the hydrothermally treated SrSn(OH) 6 nanowires at 700 °C for 3 h in air. In particular, it was the first attempt to test the electrochemical properties of the SrSnO 3 products as anode in a Li ion battery. The resulting SrSnO 3 nanorods exhibited a better cyclability over 50 cycles with a reversible lithium storage capacity of 200 mA h g ―1 than that of SrSnO 3 nanoparticles.

Uniform crystalline MgSn(OH) 6 nanocubes were synthesized by a hydrothermal method. The influences of reaction conditions were investigated and the results showed that the solvent constituents significantly affected the shape and size of MgSn(OH) 6 ·SnO 2 /Mg 2 SnO 4 has been obtained by thermal treatment at 850 °C for 8 h under a nitrogen atmosphere using MgSn(OH) 6 as the precursor. The electrochemical tests of SnO 2 /Mg 2 SnO 4 revealed that SnO 2 /Mg 2 SnO 4 has a higher capacity and better cyclability compared to pure SnO 2 or Mg 2 SnO 4 . The electrochemical performance of SnO 2 /Mg 2 SnO 4 was sensitive to the size of the nanoparticles. The lithium-driven structural and morphological changes of the electrode after cycling were also studied by the ex-situ XRD pattern and TEM tests. This work indicates that SnO 2 /Mg 2 SnO 4 is a promising anode material candidate for application in Li-ion batteries.

Nickel hydroxyl sulfate (Ni(SO4)0.3(OH)1.4) nanobelts were obtained via a simple template-free hydrothermal reaction. The structural evolution of Ni(SO4)0.3(OH)1.4 nanobelts during ex situ heat treatment and in situ electron irradiation are investigated using transmission electron microscopy (TEM) techniques mainly including bright-field imaging, selected-area electron diffraction combined with kinematic simulations, and high-resolution TEM. The transformation from Ni(SO4)0.3(OH)1.4 to NiO can be observed in both ex situ and in situ experiments. Based on the TEM results, the structural evolution is clarified and the preliminary structural framework of Ni(SO4)0.3(OH)1.4 is proposed. This structural evolution also provides an excellent approach for large-scale production and/or modification of NiO nanoparticles.

FeS and FeS2 nanosheet films were selectively synthesized on iron substrates through one-step hydrothermal treatment of iron foil and sulfur powder in the presence or absence of hydrazine. The resulting FeSx (x = 1, 2) nanosheet films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) and used as novel photocathodes in tandem solar cells with dye-sensitized TiO2 nanorod films as the corresponding photoanode. The photovoltaic properties of the tandem dye-sensitized solar cells were carefully studied. We found that the performance of the FeS nanosheet film photocathode was better than that of the FeS2 one in the tandem dye-sensitized solar cells. In the case of the FeS nanosheet film photocathode, a short circuit photocurrent (Isc) of 2.53 mA/cm2, an open circuit photovoltage (Voc) of 0.60 V, a fill factor (FF) of 0.31, and conversion efficiency (η) of 1.32% were obtained under an illumination of 100 mW/cm2. This study suggests that ...

Low-dimensional single-crystalline CdCO3 nanostructures such as nanowires, nanobelts, nanorolls, and one-dimensional (1D) hierarchical structures have been synthesized through a convenient, low-temperature hydrothermal method, and the products have been characterized by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, and selected area electronic diffraction. The influences of ammonia concentration, reaction time, and temperature on the morphologies of CdCO3 have been investigated. In addition, these low-dimensional nanostructures can be transformed into oriented CdO nanoporous structures through heat treatment processing, and the corresponding shapes can be preserved completely.

ZnO nanoparticles which have diameter of 15 nm were prepared by hydrothermal method. ZnO nanosheets were obtained by rehydrothermal treatment of ZnO nanoparticles. The phase and morphology were investigated by using transmission electron microscope, scanning electron microscope and X-ray diffraction. Also, absorbance spectra were measured by using a UV–vis spectrophotometer. A fill factor of 0.55, short-circuit current of 2.059 mA/cm 2 , open-circuit voltage of 0.593 V and an overall light to electricity conversion efficiency of 1.55% for the solar cell based on ZnO nanosheets were obtained. r 2007 Elsevier B.V. All rights reserved.

Novel nanocrystalline TiO 2 films with the textural channels are obtained for dye-sensitized solar cells (DSSCs). The textural channels consisting of the cracks on the surface and the nanopores with average diameter of about 41 nm are produced by packaging ZnO nanowires with diameter of 30–50 nm into TiO 2 films and subsequently etching ZnO nanowires by hydrochloric acid. The performances of DSSCs based on novel TiO 2 films (with the textural channels) and traditional TiO 2 films (without the textural channels) are investigated, respectively. When two kinds of typical quasi-solid-state electrolytes and one kind of solid-state electrolyte are used, the energy conversion efficiencies of DSSCs from novel TiO 2 films are improved by 20–30% compared to that from traditional TiO 2 films. The reasons for the great improvement are investigated chiefly by UV–vis absorption spectra, field emission-scanning electron microscope (FE-SEM) and electrochemical impedance spectroscopy (EIS) technique. The results show that the introduction of the textural channels facilitates better penetration of quasi-solid/solid-state electrolytes into the nanopores of novel TiO 2 films and thus results in better interfacial/electrical contact and faster interfacial reaction.

In this paper, large-scale, single-crystalline ZnO nanotube arrays were directly fabricated onto F-doped SnO2 (TCO) glass substrate via an electrochemical deposition method from an aqueous solution for the first time. The tubes had a preferential orientation along the [0001] direction and hexagon-shaped cross sections. The novel nanostructure could be easily fabricated without a prepared layer of seeds on the substrate. The surface condition of substrate material and the experimental conditions played a key role in the nanotube formation. A possible formation mechanism has been proposed. Keywords: ZnO nanotube, Arrays, TCO glass, Electrochemical deposition

Antimony-doped tin oxide (ATO) suspension with monodispersion has been directly synthesized by hydrothermal method by using mixed Sb/Sn hydroxide solution as precursor, and temperature control has been used during the crystal growth. The ATO particles were characterized by XRD, TEM, SEM–EDS and resistance test. X-ray diffraction shows that all Sb ions come into the SnO 2 lattice to substitute Sn ions. The crystallinity and doping of Sb are improved through stage heating, compared with that at constantly high temperature. TEM and SEM images indicate the ATO nanoparticles are monodispersed with the size ranging from 10 to 15 nm. The process of stage heating can enhance Sb doped level and realize the synthesis of monodispersed doped oxide particles under low temperature in a short time. The possible growth mechanism is proposed.

Electrodeposition of nanoporous ZnO films and their applications to dye-sensitized solar cells (DSSCs) were investigated in the aim of developing cost-effective alternative synthetic methods and improving the ZnO-based DSSCs performance. ZnO films were grown by cathodic electrodeposition from an aqueous zinc nitrate solution containing polyvinylpyrrolidone (PVP) surfactant. PVP concentration had strong effects on the grain sizes and surface morphologies of ZnO films. Nanoporous ZnO film with grain size of 20–40 nm was obtained in the electrolyte containing 4 g/L PVP. The X-ray diffraction pattern showed that nanoporous ZnO films had a hexagonal wurtzite structure. Optical properties of such films were studied and the results indicated that the films had a band gap of 3.3 eV. DSSCs were fabricated from nanoporous ZnO films and the cell performance could be greatly improved with the increase of ZnO film thickness. The highest solar-to-electric energy conversion efficiency of 5.08% was obtained by using the electrodeposited double-layer ZnO films (8 μm thick nanoporous ZnO films on a 200 nm thick compact nanocrystalline ZnO film). The performance of such cell surpassed levels attained in previous studies on ZnO film-based DSSCs and was among the highest for DSSCs containing electrodeposited film components.

The adsorption of nicotine and tar from the mainstream smoke (MS) by the filter tips filled respectively with oxidized carbon nanotubes (O-CNTs), activated carbon and zeolite (NaY) has been investigated. O-CNTs show exceptional removal efficiency and their adsorption mechanism is investigated. Capillary condensation of some ingredients from MS in the inner hole of O-CNTs is observed and may be the primary reason for their superior removal efficiency. The effect of O-CNTs mass on the removal efficiencies is also studied and the results show that about 20–30 mg O-CNTs per cigarette can effectively remove most of nicotine and tar.

The grain size in cuprous oxide (Cu 2 O) thin films is a key to improve the performance of solar application devices. In this paper, electrochemical deposition of nanocrystalline Cu 2 O thin films on TiO 2 films coated on transparent conducting optically (TCO) glass substrates by cathodic reduction of cupric acetate has been investigated. The deposition kinetics of nanocrystalline Cu 2 O thin films were studied and the parameters limiting the deposition of the films were determined. Pure Cu 2 O deposited at bath temperature between 0 and 30 °C produced spherically shaped grains with 40∼50 nm diameters which have not been reported previously. The effect of pH was studied and a solution with a pH between 5.5 and 6 was found to be best. The effect of annealing on bulk structure, electrical resistivity, and optical absorption of nanocrystalline Cu 2 O thin films was also studied and the results were discussed.

The blend system containing a poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer (68/32 mol %) and poly(vinyl acetate) (PVAc) was miscible from the results of differential scanning calorimetry (DSC) studies that exhibit the presence of a single, composition-dependent glass transition temperature (T g ) and a strong melting point depression for the semicrystalline P(VDF/TrFE) component. However, differences between the DSC and dielectric measurements, which showed a separate P(VDF/TrFE) T g peak, suggests that the P(VDF/TrFE)/PVAc blends are actually partially miscible. Because of the lower dielectric constant of PVAc and the reduced sample crystallinity caused by the addition of PVAc, both the dielectric constant and the remanent polarization of the copolymer blends decrease with increasing PVAc content. The presence of a small amount of PVAc stabilized the anomalous ferroelectric behavior of ice-water-quenched P(VDF/TrFE), and the blend portrayed normal polarization reversal behavior after adding only 1 wt % PVAc. The piezoelectric response suggests small changes with an increasing number of poling cycles. It is believed that PVAc affects the D-E hysteresis behavior at the interface between crystalline and amorphous phases, although much work remains to be done to confirm this hypothesis.

A high-performance supercapacitor electrode is designed and fabricated with the 3D interconnected continuous nanoporous Co/CoO core-shell hybrid nanostructure grown on nickel foam. The Co/CoO core-shell hybrid nanostructures are obtained via a hydrothermal method, followed by high-temperature annealing in hydrogen atmosphere, and finally placed in air at 50 °C for 1 h. The Co/CoO core-shell nanostructure assembled by a conductive metal-core and a CoO shell, brings low resistance, high specific capacitance of 5.632 F cm-2 and good capability stability (81.5% capacitance retention after 6000 cycles). An asymmetric supercapacitor device built by the Co/CoO (positive electrode) and activated carbon (negative electrode) can deliver a working voltage of 1.7 V and display a high energy density of 0.002 67 Wh cm-2 at a power density of 0.001 62 W cm-2, which is far superior to that of a supercapacitor at a similar power density.

Nanobelts of nickel hydroxyl sulfate have been prepared on a large scale via a simple template-free hydrothermal reaction on the basis of a complex [Ni(NH(3))(6)](2+) formed with Ni(2+) and ammonia in an ethanol-water solution. The as-synthesized nanobelts were single crystals, with several tens of microns in length and 50-150 nm in width. The nanobelts were enclosed by top surfaces (100) and side surfaces (001) and their growth direction was parallel to [010]. The function of aqueous ammonia and ethanol was discussed. Furthermore, nanostructures of a mixture of crystralline NiO and amorphous nickel sulfate with various morphologies, such as nanobelts, porous nanobelts, and nanoparticles, were obtained by the thermal treatment of the as-synthesized Ni(SO(4))(0.3)(OH)(1.4) nanobelts at different temperatures.

Catalytic activity of cuprous oxide (Cu2O) micro-particles with cubic, octahedral, truncated-octahedral and hollow opened sphere structures for thermal decomposition of ammonium perchlorate (AP) was investigated in this paper. Cu2O with different morphologies were synthesized through one-pot hydrothermal method, which is based on the reduction of Cu(II) with d -(+)-glucose in an alkalic solvent. Morphology, crystal structure and specific surface area of final samples were characterized by using SEM, XRD, and BET, respectively. TG/DTA results show that the samples with different morphologies exhibit quite different catalytic activity in different stage of thermal decomposition of AP. Through comparing them, Cu2O micro-octahedrons with {1 1 1} facets show better catalytic effect than cubes with only {1 0 0} facets, while the Cu2O hollow microspheres enhance the high-temperature exothermic decomposition of AP significantly. The authors also discussed some underlying catalytic mechanism and offered some selection basis of catalysts in the thermal decomposition of AP.

Ring-opening terpolymerization of L-lactide (LA), -caprolactone (CL), and glycolide (GA) was performed in the presence of tin (II) 2-ethylhexanoate at 170 degrees C. Random terpolyesters with weight-average molecular weight up to 130,000 g/mol were obtained. These terpolyesters, especially those with LA:CL:GA composition of 3:1:1, provided good coating integrity following spraying onto bare metal stents. The semi-synthetic macrolide immunosuppressant, everolimus, was incorporated into the terpolyester coating, and its release from the stent was evaluated. Unlike PLLA homopolymers, which are immiscible with the drug and non-optimal for controlled release, these terpolymers gave excellent control in a screening study, by tuning terpolymer molecular weight, relative monomer ratio, and drug-to-polymer ratio. Adjusting the polymer properties to improve drug solubility (or miscibility) in the polymer coating was found beneficial to the release profile.

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degrees C in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets.