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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.

The design of artificial photosynthetic systems (APSs) with hierarchical porosity by taking into account liquid flow and gas transport effects is of high significance. Herein we demonstrate a general and facile strategy to prepare hierarchical 1D to 3D macro/meso/nanoscopic morph-tunable g-C3N4 assemblies via bio-directed morphology engineering for enhanced artificial photosynthesis of CO and methane via CO2 reduction. Escherichia coli (1D), Papilio nephelus wings (2D, planar) and cole pollen (3D) are adopted for 1D to 3D multiscale assemblies with high surface areas via a two-step transformation process. Moreover, liquid flow and gas diffusion behaviors are investigated using COMSOL computational simulation to reveal the relationship between structural effects and output efficiency theoretically. Such methodology can be extended to realize versatile fabrication of various morph-tunable carbon nitride assemblies. Importantly, this research illustrates the power of combining theoretical calculations and experimental techniques to achieve the controlled design of high efficiency APS and may provide further avenues to APS optimization.

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.

The state-of-the-art perovskite solar cells (PSCs) with SnO2 electron transporting material (ETL) layer displays the probability of conquering the low electron mobility and serious leakage current loss of the TiO2 ETL layer in photoelectronic devices. The rapid development of SnO2 ETL layer has brought perovskite efficiencies >20%. However, high density of defect states and voltage loss of high temperature SnO2 are still latent impediment for the long-term stability and hysteresis effect of photovoltaics. Herein, Nb5+ doped SnO2 with deeper energy level is utilized as a compact ETL for printable mesoscopic PSCs. It promotes carrier concentration increase caused by n-type doping, assists Fermi energy level and conduction band minimum to move the deeper energy level, and significantly reduces interface carrier recombination, thus increasing the photovoltage of the device. As a result, the use of Nb5+ doped SnO2 brings high photovoltage of 0.92 V, which is 40 mV higher than that of 0.88 V for device based on SnO2 compact layer. The resulting PSCs displays outstanding efficiency of 13.53%, which contains an ∼10% improvements compared to those without Nb5+ doping. Our study emphasizes the significance of element doping for compact layer and lays the groundwork for high efficiency PSCs.

With the development of deep learning technologies, object detection algorithms have made significant progress in terms of detection speed and detection performance. However, the detection speed of current detection networks still does not meet the requirements of real-world applications in some scenarios. In this paper, we propose a faster non-maximum suppression (FNMS) algorithm that reduces the processing time by a large margin while achieving the same detection precision compared with the traditional non-maximum suppression (NMS) algorithm. Moreover, an attempt is made to adopt additional lightweight network structures to improve the speed of the detection network. By combining our FNMS algorithm with other network optimization strategies, we are able to improve the detection speed of YOLO v3 on the DOTA dataset by 165%.

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.

Herein, gas bubbles generated in situ from precursors assist the rapid construction of hollow sycamore fruit-like CoMoO4 spheres (HSCSs). This bubble-assisted fabrication strategy is easy to operate, ultra-fast, low cost and post-treatment-free, showing great potential for the large-scale production of HSCSs. The growth mechanism of HSCSs is discussed to reveal the evolution process, which may be generalized to the construction of a series of hollow ternary Mo-based oxides. The obtained HSCSs exhibit a superior specific capacitance and outstanding cyclic stability when applied in supercapacitors.

Facile engineering ultrathin nano structural materials is still a huge challenge for material science. Thereinto, the strategy of exfoliating shows great advantages. In this work, we develop a convenient approach to exfoliate Co(OH)

A facile hydrothermal method is developed for fabrication of large-scale NiMoO4·H2O arrays with robust adhesion on Ni foam. Importantly, the morphology of NiMoO4·H2O can be easily controlled to be nanoflake (H-NF) or nanowire (H-NW) arrays by using NH4F as additive. The obtained nanoflake morphology delivers better electrochemical activity than that of nanowire. The electrochemical performance of anhydrous NiMoO4 arrays obtained by annealing the NiMoO4·H2O has also been investigated for comparison. It is believed that the presence of the structural water of NiMoO4 enhances the capacitive performance by making it a good ionic conductor. Furthermore, an asymmetric supercapacitor (ASC) is constructed using the as-prepared NiMoO4·H2O nanoflake arrays as the positive electrode and activated carbon (AC) as the negative electrode. The optimized ASC with an extended operating voltage range of 0–1.6 V displays excellent electrochemical performance with a high energy density of 53.8 W h kg−1 at a power density of 239 W kg−1 in addition to superior rate capability. Moreover, the H-NF//AC ASC device exhibits remarkable cycling stability with 73.4% specific capacitance retention after 4000 cycles. Our result shows that this unique NiMoO4·H2O nanoflake array is promising for electrochemical energy applications.

A one dimensional nanostructure array has been considered as a successful charge transport material for perovskite solar cells (PSCs), because of its large internal surface area, superior charge collection efficiency and fast charge transport. Herein we demonstrate a ZnO nanorod (NR) array as the electron collector in a hole-conductor-free PSC with a carbon counter electrode (CE). A relatively low initial power conversion efficiency (PCE) of 5.6% was achieved using a 1 μm long ZnO NR array as an electron collector. However, by introduction of a thin TiO2 coating layer on the surface of ZnO via TiCl4 treatment, the PCE of the cell has been improved to the highest value of 8.24%. It is revealed that the performance enhancement of the ZnO/TiO2 NR based PSCs is largely attributed to the larger surface area, reduced electron combination, and superior electron transport properties.

CuO nanoarrays (CNAs) and Fe-incorporated CuO nanoarrays (FCNAs) were fabricated by hydrothermal method. Addition of Fe salt to the reaction mixture allowed the introduction of iron oxide onto the CNAs surface, which was characterized by XPS and HRTEM. Introducing Fe ion into reaction precursor significantly affected not only the morphologies of as-prepared products but also their electrochemical performance as anode for lithium ion full battery. The FCNAs electrodes showed higher specific capacity and better capacity retention at different current densities than that of CNAs.

A sandwich-structured porous supercapacitor electrode layered by MnO2/Polyaniline/MnO2 (MPM) was constructed by electrochemical deposition and in situ polymerization method. As a supercapacitor electrode, it had uniform mesoporous structure and a fast electron transport high-way due to the electrochemical deposition method and the middle thin layer of conductive polyaniline which could dramatically enhance the conductivity of MnO2. In three-electrode system, this sandwich-structured MPM electrode has superior capacitive performance to electrode which consists of only two layers of MnO2 (MM).

Zn 3 (OH) 2 V 2 O 7 ·2H 2 O samples with high visible-light photocatalytic water oxidation activity were hydrothermally fabricated at different pH conditions. The crystalline phase, morphology and local crystal structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), corresponding selected area diffraction (SAED) and Raman techniques. According to the SEM results, all the samples exhibited aggregates of irregular nanoplates with the average diameter of 100–200 nm and thickness of ∼20 nm. Furthermore, some factors, such as pH conditions, influencing the morphologies and local crystal structure of the Zn 3 (OH) 2 V 2 O 7 ·2H 2 O nanoplates have been systematically investigated. The photocatalytic activities of the Zn 3 (OH) 2 V 2 O 7 ·2H 2 O were evaluated by photocatalytic water oxidation under visible light irradiation. It was found that Zn 3 (OH) 2 V 2 O 7 ·2H 2 O prepared at low pH exhibited high photocatalytic water oxidation activity, indicating that different morphologies and the different extent of local crystal structure distortion can effectively influence the water oxidation activity of Zn 3 (OH) 2 V 2 O 7 ·2H 2 O. Moreover, the relationship between the exposed facets of Zn 3 (OH) 2 V 2 O 7 ·2H 2 O and the H 2 O molecule adsorption was investigated by density functional theory (DFT). The results of our study indicated that the extent of connection between polyhedrons on exposed facet of the Zn 3 (OH) 2 V 2 O 7 ·2H 2 O can significantly affect the sample's H 2 O molecule adsorption activity.

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 report a facile, rapid and low-cost two step approach to synthesize hierarchical CuO@MnO 2 core–shell nanosheet arrays directly on Cu foil substrate. The as prepared CuO@MnO 2 arrays can be directly used as integrated electrodes. Furthermore, the CuO@MnO 2 nanosheet arrays were assembled with the commercial Li Ion Battery Cathode (LiCoO 2 ) as a full cell, which exhibited high capacity and good cycle stability (120 mA h g −1 after 100 cycles at a rate of 150 mA g − 1 ) and an excellent rate performance (a stable capacity of about 127 mA h g −1 after 100 cycles of variable charging rate). The excellent performance of the CuO@MnO 2 hybrids comes from their intelligent integration of the two compatible components into unique hierarchical architectures with a high specific capacity. Primary single-crystalline CuO nanosheet arrays directly grown on Cu substrates allow for efficient electrical and ionic transport. The secondary MnO 2 shell provide enhanced surface area and high theoretical Li + storage capacity, and can also serve as volume spacers between neighboring CuO nanosheet arrays to maintain electrolyte penetration as well as reduce the aggregation during Li + intercalation, thus leading to improved electrochemical energy storage performance.

We developed a facile method for the synthesis of visible light responsive ZnO through the introduction of different concentrations of oxygen vacancy for efficient formaldehyde photodegradation under visible light irradiation. The visible light active ZnO was prepared using ZnO 2 instead of traditional Zn(OH) 2 as a precursor. According to the results of Raman and XPS, the concentrations of oxygen vacancy decreased with the increase of annealing temperatures. The effects of different concentrations of oxygen vacancy on the electronic structure of ZnO were investigated by density functional theory (DFT) simulation and the results were confirmed by UV–VIS spectra, which showed the oxygen vacancy narrowed the band gap of ZnO. ZnO with stable concentration of oxygen vacancy was used for formaldehyde photodegradation. The results of photocatalytic experiments reflected that oxygen vacancy can not only act as impurity levels in the band structure of ZnO but can also work as electron traps to accept the photogenerated electrons. The oxygen vacancy in ZnO effectively prohibited the recombination of electron–hole pairs, enhancing the photocatalytic activity of ZnO. The results of our study provide us useful information for the understanding of the mechanisms of the photocatalytic process of ZnO with oxygen vacancy.

Manganese dioxide (MnO 2 ) and CuBi 2 O 4 -doped MnO 2 thin films with different nanostructures were deposited on indium tin oxide (ITO) glass and Ti foil substrates by using a chemical bath deposition (CBD) technique. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron microscopy (XPS). The effects of doping and substrates on electrochemical properties of MnO 2 and CuBi 2 O 4 -doped MnO 2 thin films on ITO glass and Ti foil were investigated. Capacitive properties of MnO 2 and CuBi 2 O 4 -doped MnO 2 thin films electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 0.1 M Na 2 SO 4 aqueous solution as electrolyte. Specific capacitance, obtained from electrochemical measurement for the CuBi 2 O 4 -doped MnO 2 , exhibited a higher value of 338 F g −1 compared to the MnO 2 exhibiting value of 135 F g −1 . In addition, CuBi 2 O 4 -doped MnO 2 thin films on an ITO electrode had a better and satisfactory specific capacitance value, and exhibited more excellent electrochemical stability and reversibility than Ti foil substrates.

Motivated by a Canadian national survey on child safety seat use, we propose a procedure for incorporating non-ignorable missingness in a binary response using logistic regression model with random effects. The proposed method applies an expectation maximization (EM) algorithm to the Penalized quasi-likelihood of the artificially completed data. We provide closed form formulae for estimating the covariance of the regression coefficients as well as the odds ratios of interest and probabilities of missingness. The proposed algorithm can be easily implemented by using familiar statistical packages that fit generalized linear mixed models. The method is illustrated by applying it to data from Canadian national survey on child safety seat use.

The Au nanoparticle sandwich double spheric-shells of SiO

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.

Novel ZnO/SnO 2 core–shell nanoneedle arrays were developed with a two-step synthesis strategy. The strategy combines two processes: a hydrothermal synthesis of a ZnO nanoneedle array and a coating of a SnO 2 layer on the surface of the ZnO nanoneedle. The addition of F − to the hydrothermal reaction solution played an important role in the formation of the ZnO nanoneedle array. The ZnO/SnO 2 core–shell structure was successfully achieved after depositing a thin SnO 2 layer on the ZnO nanoneedle by dip-coating. Dye-sensitized solar cells (DSSCs) based on ZnO/SnO 2 core–shell nanoneedle arrays were assembled, and a high conversion efficiency ( η ) of around 4.71% was obtained at 0.9 suns. This can be attributed to the advantages of the core–shell structure. On the one hand, it affords a larger surface area for a more dye loading and light harvesting, which result in enhancing the photocurrent of the DSSC. On the other hand, the core/shell structure passivates nanoneedle surface defects for suppressing the recombination, which leads to the increase of the open-circuit voltage. Accordingly, the enhanced photocurrent and open-circuit voltage have led to a prominent increase in the photovoltaic efficiency of around 4.71%, which is much higher than that of an ordinary ZnO nanoneedle array-based DSSC.

Manipulating biomacromolecules and micro-devices with light is highly appealing. Opto driving torque can propel micro-rotors to translational motion in viscous liquid, and then separate microsystems according to their handedness. We study the torque of dielectric loss generated by circular polarized lasers. The unwanted axial force which causes the handedness independent translational motion is cancelled by the counter propagating reflection beams. The propelling efficiency and the friction torque of water are obtained by solving the Navier-Stokes equation. In the interesting range of parameters, the numerical friction torque is found to be linear to the angular velocity with a slope depending on the radius of rotor as r 3. The time-dependent distribution of angular velocity is obtained as a solution of the Fokker–Planck equation, with which the thermal fluctuation is accounted. The results shed light on the micro-torque measurement and suggest a controllable micro-carrier.

Diverse biological microstructures that result in advanced optical effects have been systematically investigated. However, the mechanisms of polarization-sensitive color have not been fully understood. Here, we report a combined architecture comprising upper deep grating and bottom multilayer in butterfly iridescent scales that leads to polarization-sensitive color related with scale azimuth. The polarization process is unraveled through detailed investigations on the green scales in butterfly Ornithoptera priamus poseidon and the orange scales in butterfly Ornithoptera croesus lydius. The bright green and orange scales result from the interaction between the transmitted 0th order diffraction of upper grating and the 1st order interference of the bottom multilayer. Combining experimental results with calculation, we clarify the structural origin and the mechanism of the polarization conversion. Tapered grating achieves form-birefringence rotating polarized light and the multilayer selectively reflects the incident light dominating the reflection color. The height of the grating, which determines the phase difference of the two decomposed polarized lights, is essential to polarization conversion. To our knowledge, it is the first study to provide a structural prototype comprising deep grating and multilayer for achieving polarization-sensitive color. These findings show significant promise in biosensing, anticounterfeiting and optical-material design.

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.

A novel carbon-CoO-NiO-NiCo2O4 integrated electrode has been designed by reducing the hetero-structured NiCo2O4 nanosheet array with C2H2 on the nickel foam at a low temperature of 350 °C. The topotactical transformation from NiCo2O4 to the integrated electrode has been first conceived and investigated. Such unique nanoarchitectures exhibit excellent electrochemical performance with ultrahigh capacitance and desirable cycle life at high rates.

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 series of D−A type CdIIX2L (X = Cl, Br, I) complexes with asymmetric structures were designed, synthesized and fully characterized. Structural studies indicate that Cd(II) has five-coordination with three N from terpyridine and two halides to form distorted square pyramidal complexes. The stereo-structure of the metal complexes can effectively reduce interactions between the complex molecules avoiding fluorescence quenching of the metal complexes in the solid state. The Cd(II) complexes also showed strong two-photon absorption in the near-infrared range by aperture Z-scan technique using a femtosecond laser in the solid state, with excellent two-photon absorption coefficients. The band gaps of the complexes suggested that they have potential applications in semiconductor materials and may be useful in near-IR nonlinear optical materials.

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.

Zn-doped Cu2O polyhedrons with various crystal morphologies, from 50-facet and 26-facet to 8-facet, were synthesized via a mild, low-temperature process based on the hydrothermal method. Addition of zinc salt to the reaction mixture might allow the introduction of Zn ions into the Cu2O crystal lattice, which is shown by X-ray photoelectron spectroscopy and energy dispersive spectroscopy. Doping of Cu2O crystals with Zn affects not only their morphologies but also significantly influences their optoelectronic properties. UV–visible and photoluminescence (PL) tests showed that the Zn-doped Cu2O system displays an increased band gap and enhanced photoluminescence properties. The open circuit potential-time (Ocp-t) method shows that a pure Cu2O crystal is an n-type semiconductor, while the Zn-doped Cu2O crystal shows p-type characteristics.

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 this paper, we design a strategy to obtain core–shell carbon-coated CaSnO3 nanotubes (hereafter C-CTO NTs) directly via a facile subsequent solvothermal synthesis using CaSn(OH)6 nanotubes as precursor in a mixed ethanol and water solvent. The mixed solvent not only facilitates the phase transformation of CaSnO3 from CaSn(OH)6 to take place quickly, but also retains the tube-shaped morphology. The uniform decoration of C shell on the surface of CaSnO3 nanotubes (hereafter CTO NTs) was confirmed by EELS (electron energy loss spectroscopy). Moreover we found that the uniform carbon-coating layer on the surface of CTO NTs played roles of a good conductor and a structure buffer to alleviate the strains from the volume variation of CTO NTs cores. So the core–shell structure possesses both the electroactivity of C and the advantages of nanotube structure. When used as an anode for Li ion battery, it shows enhanced cycling performance in term of cycling stability over bare CTO NT electrode and CaSnO3 nanocube (hereafter CTO NC) electrode. To our best knowledge, this is the first attempt to use C-CTO NTs as an anode in Li ion battery.

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.

A ZnO/C core/shell structure has been synthesized using in situ CVD. A ZnO nanowire array on a Ti substrate was used as both the template and catalyst. The carbon shells form a unique wrinkled scal...

Zn 2 SnO 4 –SnO 2 heterojunction nanocomposites (ZTO–SnO 2 ) with high mass amount of ZTO were synthesized by a two-step technique. The route involves firstly the synthesis of monodispersed ZnSn(OH) 6 nanocubes with a 50–60 nm edge length as precursors by simple coprecipitation of Na 2 SnO 3 ·3H 2 O and ZnCl 2 aqueous solution, assisted by ultrasonic treatment and then followed by calcination of the precursors at 800 °C under N 2 atmosphere. The as-synthesized nanoparticles were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Heterojunction between ZTO and SnO 2 nanoparticle was confirmed by the electron energy loss spectroscopy (EELS) elemental mapping and high-resolution TEM (HRTEM). The photovoltaic performance of the ZTO–SnO 2 based DSSC was examined by measuring the J- V curves both in dark and under illumination. The results show that the ZTO–SnO 2 based DSSC exhibits superior photovoltaic performance as compared to the single phase ZTO based DSSCs. Under illumination of AM 1.5 simulated sunlight (100 mW/cm 2 ), the open circuit voltage of the cell based on ZTO–SnO 2 is 706 mV, the short-current density is 2.85 mA/cm 2 , and the efficiency is 1.29% which is increased by 43% from 0.90% to 1.29% compared with pure ZTO. The formation of the heterojunctions between ZTO and SnO 2 nanoparticles is believed to reduce the recombination between injected electrons and redox I − /I 3 − and improve the performance of the DSSC.

We present a strategy to synthesize porous BaSnO 3 hollow architectures with that were 150–300 nm in diameter and 1.5–5 μm in length using precursor of BaCO 3 @SnO 2 nanorods prepared by hydrothermal treatment. BaCO 3 @SnO 2 nanorods, consisting of a BaCO 3 core and a SnO 2 shell, could be used effectively for the solid-state synthesis of polycrystalline BaSnO 3 powder at 800 °C (lower than convention for BaCO 3 and SnO 2 mixtures). The core/shell structure of the precursor could play a role as a structural directing template for preparing BaSnO 3 hollow architectures during the calcination process. The X-ray diffractometer (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) are employed to characterize the structures and morphologies. When applied to DSSC, the porous BaSnO 3 hollow architectures exhibit distinct photovoltaic effect.

High density aligned ZnO nanotube (NT) arrays were synthesized using a facile chemical etching of electrochemically deposited ZnO nanorods (NRs). The influence of etching time and solution concentration on the ZnO NT formation was investigated. Moreover, cadmium selenide (CdSe) nanoparticles as sensitizers were assembled onto the ZnO NT and NR arrays for solar cell application. A conversion efficiency ( η ) of 0.44% was achieved for CdSe/ZnO NT-based solar cell under the white light illumination intensity of 85 mW/cm 2 . An 8% enhancement in η was observed between the CdSe/ZnO NT-based and NR-based solar cell due to the enhancement of the photocurrent density. ZnO NT arrays have been proved to have a superior ability as compared with ZnO NR arrays when employed as a semiconductor film.

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.

CaSn(OH)(6) nanotubes were fabricated by sonochemical precipitation method at room temperature. A direct rolling process from nanosheets to nanotubes was expected for the synthesis of CaSn(OH)(6) nanotubes. The transient CaSn(OH)(6) nanosheets are formed as intermediates produced by the spontaneous self-assembly and transformation of amorphous colloid clusters. During the crystallization process of intermediate nanosheets, the relaxation of surface strain in the nanosheet interfaces can induce the nanosheets to roll up to form nanotubes under ultrasonic conditions. In this synthesis, the addition of Na(2)CO(3) seems to play an important role in the formation, size, and shape control of the nanotubes. Investigations into the stability performance of the nanotubes indicate that the morphologies are very sensitive to pH and temperature. The method suggests a general strategy for the design and fabrication of functional single-crystalline nanotubes through an intermediate nanosheet rolling process. The in vitro fabrication of such single crystal nanotubes could shed light on fundamental mechanisms for closed hollow nanostructures. Furthermore, nanotubes produced in high yield and at low cost are envisioned to have applications in areas ranging from medicine to pharmaceuticals through to materials science.

ZnO/CdSe core-shell nanorod array films were synthesized via a two-step method. ZnO nanorod array films were first grown on a TCO substrate, and then CdSe nanocrystals were deposited on the nanorods to form core-shell structured films. The resulting films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis absorption spectroscopy. Especially, dark-field images and transmission electron diffraction of the TEM were used to study the morphology and the chemical nanostructure of the ZnO/CdSe core-shell nanorods in detail. We investigated the photovoltaic performance of the resulting ZnO/CdSe core-shell nanorod array films as solar cell photoanodes. Parameters, such as the length of the ZnO nanorods, the shell phase structure and the deposition time of the CdSe nanocrystals were found to affect the photovoltaic performance of the solar cell. This study provides a facile method to prepare nanocomposite photoanodes of solar cells, and gives some insight about the fundamental mechanisms that improve the performance.

In the present work, we report for the first time an investigation on anodic oxidation of tin in an electrolyte of dimethyl sulfoxide (DMSO)/water mixtures containing citric acid in the trans-passive region. The anodization leads to the formation of flowerlike patterns composed of tin citrate complex nanostrips on tin substrates. The products were characterized using XRD, SEM, TEM, FTIR, and XPS measurements. The formation mechanism of the tin citrate complex microstructures is discussed and the influences of the voltage, citric acid concentration, and electrolyte composition on the morphology of the microstructures were investigated. The nanostrips with a smooth surface can be transformed to polycrystalline SnO2 nanostrips with a porous structure by a thermal annealing process. This work developed a simple, clean, and effective route for fabrication of large area SnO2 nanostructured films.

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.