Composite Nanorods Research Articles

Photoelectrochemical activity of CdS/Ag/TiO2 nanorod composites: Degradation of nitrobenzene coupled with the concomitant production of molecular hydrogen

TiO2 nanorods decorated with CdS and Ag0 were prepared and anchored on to a fluorine doped tin oxide (FTO) electrode in order to investigate the photoelectrochemical (PEC) oxidation of nitrobenzene (NB) coupled with simultaneous reduction of water to produce molecular hydrogen (H2). The modified TiO2 nanorods (TiO2-NRs) prepared for 4 h have regular nanoroads with high superficial area and Ag nanoparticles loaded on the surface of nanoroads covered with CdS film uniformly. The nano-composite TiO2-NRs with photochemically active up to 700 nm with coupled photoconversion efficiencies for NB degradation and H2 production as high as 4.4%. The surface plasmon resonance (SPR) effect of Ag not only excited the photo-generated electron of Ag nanoparticles, but also promoted the electron transfer from CdS to TiO2-NRs. NB as a role of electron donor, reacts with hole to improve the efficiency of H2 production. The heterostructure electrode for solar energy conversion had an important significance for solving environmental pollution and energy crisis.

Sputtering control of Ag2O decoration configurations on ZnO nanorods and their surface arrangement effects on photodegradation ability toward methyl orange

In this study, a combinational strategy for synthesizing ZnO nanorod arrays interlaced with Ag2O particles was proposed. Hydrothermally derived ZnO nanorod templates were sputter coated with Ag2O particles. The sputtered Ag2O particles can be decorated on the surfaces of the ZnO nanorod arrays with a randomly dispersive or continuous coverage characteristic by controlling the sputtering duration. Structural analysis revealed the formation of satisfactory crystalline ZnO–Ag2O composite nanorods through the hydrothermal and sputtering methods. The ZnO–Ag2O composite nanorods exhibited a significantly enhanced photoactivity compared with that of pristine ZnO nanorods under light irradiation. Moreover, the Ag2O content and the coverage feature of the ZnO–Ag2O composite nanorods influence the photodegradation of methyl orange solution by the composite nanorods under light irradiation. The photodegradation efficiency of the ZnO nanorods was substantially enhanced when the Ag2O particles were decorated on the surfaces in a dispersive manner. This can be attributed to the optimal content of Ag2O particles and their randomly dispersive characteristic on the surface of the composite nanorods, which resulted in the efficient transfer of photocarriers and markedly suppressed the electron–hole recombination rate.

Intercalation pseudocapacitance in chemically stable Au-α-Fe2O3-Mn3O4 composite nanorod: Towards highly efficient solid-state symmetric supercapacitor device

Pseudocapacitance generally appears due to the surface or near-surface reversible Faradaic reactions. In this regard, 2D layered materials have gained substantial attention as a potential source for driving a myriad of energy storage applications owing to their unique surface-structure relationship. Here, we have demonstrated that a pseudocapacitive mechanism becomes increasingly operative when H+ ions are intercalated easily into the enhanced van der Waals gap of layered material α-Fe2O3 in Au-α-Fe2O3-Mn3O4 nanocomposite. Theoretical studies have shown an enhancement of van der Waals gap which is attributed to the intercalation of Au into the layers of α-Fe2O3. Structural and compositional characterizations have been carried out in detailed by different physical methods and are supported by theoretical studies. Electrochemical measurements show excellent specific capacitance of 580 F g−1 at 1 A g−1 along with improved capacity retention compared to the mother component α-Fe2O3 (205 F g−1 at 1 A g−1) in 0.5 M H2SO4 electrolyte in a potential window of 1.2 V. Further, electrokinetic measurements revealed that total charge stored in the nanocomposite is based on a dominant capacitive mechanism (70% of the total capacitance) along with diffusive mechanism (30% of the total capacitance) at scan rate 5 mV s−1 whereas, α-Fe2O3 exhibits 34% capacitive and 66% diffusive at same scan rate. The synthesized composite nanorod as an efficient electrode material in a solid-state symmetric supercapacitor device exhibits excellent energy density of 36.12 Wh kg−1 and power density of 1994 W kg−1 at 1 A g−1 and 10 A g−1, respectively with outstanding stability (89%) up to 2000 successive charge-discharge cycles at 10 A g−1. This work may offer a new scope for further development of intercalation pseudocapacitive nanomaterials towards achieving high energy storage supercapacitors.

Synthesis of vanadium oxide nanorods coated with carbon nanoshell for a high-performance supercapacitor

Vanadium oxide (VOx) possesses high-potential pseudocapacitive characteristics. But it is still unsatisfactory for supercapacitors because of the poor ionic diffusivity and electrical conductivity of VOx. Nanocrystallization can decrease the distance of ion diffusion, then improve the ionic diffusivity. Suitable carbon coating could heighten conductivity and provide ion pathways. Here we synthetized V6O13@C by a sol-hydrothermal method, then pyrolyze to form VOx@C core-shell nanorod composites. The carbon nanoshells with abundant pores on the surface of vanadium oxide improve the conductivity of the nanorod electrodes and provide sufficient ion pathways. The microstructure and electrochemical measurements reveal the V6O13@C prepared from 0.8 g V2O5 raw material under 700 °C heating possesses optimal performance. As the electrode materials of a symmetric supercapacitor, such VOx@C core-shell nanorods possess a high capacity (545 F g−1 at 0.5 A g−1, 437 F g−1 at 5 A g−1) and satisfactory cyclability (88.3% retention after 2000 cycles at 0.5 A g−1). SEM and TEM show that the V6O13@C consists of uniform-size nanorods whose diameter is 20 nm with a 7-nm-thickness carbon shell layer. The favorable electrochemical performance is stemmed from unique structural features of V6O13@C nanorods. 1D structure of nanorods could significantly cut down the ion migration process as well as improving ion diffusion kinetics. Carbon nanoshell provides the high conductivity for electron, and the pores provide passageway for ion diffusion.

Enhanced photocatalytic H2 production under visible light on composite photocatalyst (CdS/NiSe nanorods) synthesized in aqueous solution

Cocatalysts play a critical role in the activity and stability of photocatalytic systems. Currently, efficient cocatalysts mainly comprise of expensive noble metals. Herein we report a composite photocatalyst consisting of CdS nanorods (NRs) and noble-metal-free cocatalyst NiSe, which efficiently enhances the hydrogen production activity of CdS NRs under visible light. NiSe was synthesized through a facile aqueous solution method and CdS/NiSe NRs composites were prepared by in situ deposition of NiSe on CdS NRs. This provides increased contact between cocatalyst and photosensitizer leading to enhanced electron transfer at the interface of NiSe and CdS. The current photocatalytic system gave the highest hydrogen evolution rate of 340 µmol h−1 under optimal conditions. The enhanced stability of the system was observed for 30 h of irradiation resulting in 14 mmol of hydrogen evolution. The highest AQY of 12% was observed using the 420 nm monochromatic light. In addition, CdS/NiSe NRs showed significant higher H2 evolution rate than that of 1.0 wt% loaded CdS/Pt NRs proving NiSe as highly efficient cocatalyst. Photoluminescence spectra and the photocurrent response were used to confirm the efficient charge transfer at the interface of NiSe and CdS nanorods. The work presented here demonstrates the successful use of an inexpensive, non-noble-metal cocatalyst for enhanced photocatalytic hydrogen production.

Designable nanoplasmonic biomarkers for direct microscopy cytopathology diagnostics.

Direct microscopy interpretation of fine-needle biopsy cytological samples is routinely used by practicing cytopathologists. Adding possibility to identify selective and multiplexed biomarkers on the same samples and with the same microscopy technique can greatly improve diagnostic accuracy. In this article, we propose to use biomarkers based on designable plasmonic nanoparticles (NPs) with unique optical properties and excellent chemical stability that can satisfy the above-mentioned requirements. By finely controlling the size and composition of gold-silver alloy NPs and gold nanorods, the NPs plasmonic resonance properties, such as scattering efficiency and resonance peak spectral position, are adjusted in order to provide reliable identification and chromatic differentiation by conventional direct microscopy. Efficient darkfield NPs imaging is performed by using a novel circular side illumination adaptor that can be easily integrated into any microscopy setup while preserving standard cytopathology visualization method. The efficiency of the proposed technology for fast visual detection and differentiation of three spectrally distinct NP-markers is demonstrated in different working media, thus confirming the potential application in conventional cytology preparations. It is worth emphasizing that the presented technology does not interfere with standard visualization with immunohistochemical staining, but should rather be considered as a second imaging modality to confirm the diagnostics.

Simultaneous and synergistic effect of heavy metal adsorption on the enhanced photocatalytic performance of a visible-light-driven RS-TONR/TNT composite

A hydrothermally synthesized rhodium/antimony co-doped TiO2 nanorod and titanate nanotube (RS-TONR/TNT) composite was prepared for removal of heavy metals and organic pollutants from water under visible light irradiation. The composite provides the dual function of simultaneous adsorption of heavy metal ions and enhanced degradation of dissolved organic compounds. Acid treatment transformed titanate nanotubes to irregular tubular structures distributed homogeneously over untransformed RS/TONRs. Synergistic removal and degradation was studied with various heavy metals, Orange (II) dye, and Bisphenol A. The adsorption capacity of the composite for heavy metal ions was Pb(II) > Cd(II) > Cu(II) > Zn(II). The adsorbed metals enhanced photocatalytic degradation of the organic pollutants, but Cu was most effective, with degradation exceeding 70% for the dye and 80% for Bisphenol A after 5 h of treatment. Photocatalytic activity was enhanced more by adsorption than photodeposition of Cu ions. A decrease in XRD rutile peak intensity with adsorbed metal indicates a change in crystallinity which may enhance photocatalytic activity. Thick and bulging nanostructures in FE-SEM images signify ion adsorption within titanate pores. BET analysis indicated titanate nanotubes with adsorbed metal are mesoporous but their tubular structure persists. XPS showed more active Cu 2p3/2 states under light, supporting an active role of Cu+ in photocatalytic ROS generation. Detection of ROS and Cu species using methanol, EDTA, pCBA, and benzoic acid probes provided strong evidence for degradation via a charge transfer mechanism. Findings demonstrate the potential of the RS-TONR/TNT composite for simultaneous removal of heavy metals and degradation of organic pollutants.

In-situ functionalization of GO sheets with AlOOH-FeOOH composite nanorods: An eco-friendly nanoadsorbent for removal of toxic arsenate ions from water

Water contaminated with arsenic (As) has become a worldwide problem due to its obligatory toxicity. Therefore, there is a great challenge for researchers to develop a cost-effective and highly efficient nanoadsorbent material for As removal. In this work, we have synthesized boehmite-lepidocrocite (AlOOH-FeOOH) composite nanorods mounted onto previously prepared graphene oxide (GO) surface (GO/AlOOH-FeOOH) by one step hydrothermal method. Then the prepared GO/AlOOH-FeOOH nanocomposite was sintered at 400 °C to form GO/Al2O3-Fe2O3 nanocomposite. Both the obtained GO functionalized nanocomposites were used as adsorbents for As(V) removal from water. The XRD, HRTEM confirmed the formation of γ (AlOOH-FeOOH) and γ (Al2O3-Fe2O3). TEM images revealed the formation of rod shape composite nanomaterials on GO surface. The GO/Al2O3-Fe2O3 showed magnetic properties with saturation magnetization value of 5.8emug−1. Among the two prepared nanoadsorbents the GO/AlOOH-FeOOH shows better adsorption properties with maximum uptake capacity of 24.6 mgg-1. The kinetics and isotherm experiments suggested that the adsorption process obeyed pseudo second order kinetic and Freundlich isotherm model. The presence of common coexisting anions including Cl-, SO42-, NO3- showed no significant effect on adsorption except PO43-. The mechanism of As(V) adsorption on GO/AlOOH-FeOOH includes electrostatic interaction and surface complexation reaction.

Design of Nanoscaled Surface Morphology of TiO2-Ag2O Composite Nanorods through Sputtering Decoration Process and Their Low-Concentration NO2 Gas-Sensing Behaviors.

TiO2–Ag2O composite nanorods with various Ag2O configurations were synthesized by a two-step process, in which the core TiO2 nanorods were prepared by the hydrothermal method and subsequently the Ag2O crystals were deposited by sputtering deposition. Two types of the TiO2–Ag2O composite nanorods were fabricated; specifically, discrete Ag2O particle-decorated TiO2 composite nanorods and layered Ag2O-encapsulated TiO2 core–shell nanorods were designed by controlling the sputtering duration of the Ag2O. The structural analysis revealed that the TiO2–Ag2O composite nanorods have high crystallinity. Moreover, precise control of the Ag2O sputtering duration realized the dispersive decoration of the Ag2O particles on the surfaces of the TiO2 nanorods. By contrast, aggregation of the massive Ag2O particles occurred with a prolonged Ag2O sputtering duration; this engendered a layered coverage of the Ag2O clusters on the surfaces of the TiO2 nanorods. The TiO2–Ag2O composite nanorods with different Ag2O coverage morphologies were used as chemoresistive sensors for the detection of trace amounts of NO2 gas. The NO2 gas-sensing performances of various TiO2–Ag2O composite nanorods were compared with that of pristine TiO2 nanorods. The underlying mechanisms for the enhanced sensing performance were also discussed.

Morphological and structural properties of ZnO nanorods coated with graphene derivative fabricated by hydrothermal method

In this work, graphene oxide coated ZnO nanorods composites were synthesized by hydrothermal method. Zn nitrate hexahydrate and hexametylenetetramine (HMTA) dissolved in deionized water used as solution growth of ZnO nanorods. Graphene oxide was prepared via modified Hummers method. Then, ZnO nanorods was coated with GO using the drop coating process. The structural properties of GO coated ZnO nanorods composite were analysed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and the average crystallite size was determined by Debye-Scherrer formula. The experimental results obtained for our material exhibit significant enhancement in properties, which is suitable for the optoelectronic applications.

Tunability of localization length in naphthalene sulfonic acid doped polyaniline/nickel ferrite composite nanorods system

Tunability of key length scales including nanodimensionality, mean free path, localization length, and cyclotron radius gives opportunities to fabricate nanodevices with new functionalities. Herein, in order to tune localization length, composite nanorods (CNRs) of 2-naphthalene sulfonic acid doped polyaniline (PANI-NSA) and nickel ferrite nanoparticles (NiFe2O4 NPs) are synthesized via an in situ chemical polymerization method. The nanorods’ structure and the incorporation of the NiFe2O4 NPs into the PANI-NSA matrix are envisaged by various characterization techniques. The presence of a hysteresis loop with minor coercivity and remanence suggests the ferrimagnetic property of PANI-NSA/NiFe2O4 CNRs at room temperature. Investigation of electrical resistivity as a function of temperature in the absence of an external magnetic field establishes quasi-one-dimensional variable range hopping conduction mechanism of the PANI-NSA/NiFe2O4 CNR samples. CNR samples with two different loadings of NiFe2O4 NPs demonstrate substantial amounts of magnetoresistance (MR) at all the temperatures (300–50 K) studied. Intriguingly, a transition from positive to negative MR is observed with an increase in temperature from 200 to 300 K for CNR samples with less amount of NiFe2O4 (CNRs 1), whereas MR is positive for CNRs with higher loading of NiFe2O4, throughout the studied temperatures. Positive and negative MR behaviors of the CNR samples are quantitatively elucidated in terms of wave function shrinkage and forward interference models. Deduced localization length from the forward interference regime for CNRs 1 is about one order of magnitude larger than that in the wave function shrinkage regime. Thus, tuning of localization length can be achieved qualitatively through appropriate loading of NiFe2O4 NPs.

Construction of direct Z‐scheme g‐C3N4/TiO2 nanorod composites for promoting photocatalytic activity

Direct Z‐scheme g‐C3N4/TiO2 nanorod composites were prepared for enhancing photocatalytic activity for pollutant removal. The characterization revealed that the g‐C3N4/TiO2 nanorod composite formed a close interface contact between g‐C3N4 and TiO2 nanorods, which was of benefit for the charge transfer and resulted in its high photocatalytic activity. The g‐C3N4/TiO2 nanorod composites exhibited higher photocatalytic activity for degradation of Rhodamine B (RHB) than bare g‐C3N4 and TiO2 nanorods. The high photocatalytic activity of g‐C3N4/TiO2 nanorod composites is attributed to the formation of the direct Z‐scheme system, in which the electrons from the conduction band (CB) of TiO2 combine with the holes from the valence band (VB) of C3N4 while the electrons from the CB of C3N4 and holes from the VB of TiO2 with stronger redox ability are used to reduce and oxidize pollutants. Based on the radical‐trapping experiments, the main reactive species for RHB degradation are O2− and ·OH, which are produced by photoinduced electrons and holes with high redox ability. This work provides insights into the photocatalytic mechanism of composite materials for the photocatalytic removal of organic pollutants.

Effect of Bi2S3 reaction concentration on the photoelectric properties of TiO2/Bi2S3 composite film

TiO2/Bi2S3 composite nanorods arrays were prepared on fluoride-doped tin oxide conductive glass (FTO) by two-step hydrothermal method to adjust the too large band gap of TiO2. The effect of Bi2S3 concentration on the composite film was studied. The crystal structure, surface morphology and photoelectric properties of the composite thin films were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV–vis), fluorescence spectroscopy (PL) and electrochemical workstation. With the increase of Bi2S3 concentration, the absorbance and current density of TiO2/Bi2S3 firstly decreased and then increased, and the transient photocurrent reached 0.16 mA cm−2, which was significantly higher than that of pure TiO2 nanorods (0.017 mA cm−2). The flat band potentials of TiO2 and TiO2/Bi2S3 nanorods were −0.5 V and −1 V, respectively, and both of them are n-type semiconductors.

Zero bias UV detection and precursor effect on properties of ZnO nanorods grown by hydrothermal method on SiO2/p-Si substrate

Here we present the effect of the precursor chemistry on the properties of ZnO nanorods prepared by using the hydrothermal method. The nanorods were grown over RF-sputtered 50 nm ZnO seed layers on integrated circuits compatible highly lattice mismatched SiO2/p-Si substrates. Two zinc sources namely zinc acetate and zinc nitrate were dissolved in solvent (a solution of deionized water and hexamethylenetetramine) in parallel to grow the highly conducting, vertically-aligned ZnO nanorods. Surface morphology and crystal structure of NRs were investigated using scanning electron microscope and X-ray diffraction. Nanorods synthesized in zinc acetate precursor's solution were highly crystalline and sparsely packed with well defined hexagonal top surface compared to nanorods grown in zinc nitrate precursors. Elemental composition of nanorods was studied using X-ray photoelectron spectroscopy. The oxygen and zinc observed in all the nanorods, zinc acetate synthesized nanorods show high atomic percentage of these two elements. To test the electrical and photo detection properties of the ZnO nanorods a metal semiconductor metal (MSM) structure was fabricated by depositing Ti/Au ohmic contacts over the nanorods. The MSM structure fabricated over the nanorods synthesized by using zinc nitrate precursor shows zero bias UV detection not reported up to present. The conducting properties of the nanorods were obtained from the current-voltage characteristics measurements of the MSM photosensor, and it is observed that the zinc acetate synthesized NRs were highly conducting. The UV detection capability of the MSM photosensor were tested by exposing UV light from light emitting diodes of same power and different wavelength. The ZnO NRs grown in zinc nitrate precursor shows high photosensitivity.

α-MnO2 nanorod/boron nitride nanoplatelet composites for high-performance nanoscale dielectric pseudocapacitor applications

We demonstrate the synthesis of a composite of α-MnO2 nanorods and dielectric boron nitride nanoplatelets(BNNPs) as an electrode material for application in nanoscale dielectric pseudocapacitors. The optimize nanocomposite delivers a significantly high specific capacitance (890 F/g at 0.41 A/g), which is >72% of the theoretical specific capacitance of α-MnO2 at a mass loading of ca. 6 wt%. Pure BNNPs exhibit negligible charge storage capacity with a specific capacitance of 1.30 F/g at 0.024 A/g. The BNNPs increase the amount of K+ insertion/extraction and the conductivity of α-MnO2 nanorods by lowering the charge transfer resistance at the electrode-electrolyte interface. This is due to the electrical polarization of dielectric BNNPs during charging and discharging, which increases the rate and amount of K+ insertion or extraction induce by electrostatic force. The nanocomposite shows good capacity retention (94.12% after 2000 cycles) with high energy and power density. This research opens up a new avenue for the development of new types of nanoscale dielectric pseudocapacitors with high capacitance by exploring other suitable metal-oxides and nanoscale dielectric material composites.

Enhancement of Acetone Gas-Sensing Responses of Tapered WO3 Nanorods through Sputtering Coating with a Thin SnO2 Coverage Layer.

WO3–SnO2 composite nanorods were synthesized by combining hydrothermal growth of tapered tungsten trioxide (WO3) nanorods and sputter deposition of thin SnO2 layers. Crystalline SnO2 coverage layers with thicknesses in the range of 13–34 nm were sputter coated onto WO3 nanorods by controlling the sputtering duration of the SnO2. The X-ray diffraction (XRD) analysis results demonstrated that crystalline hexagonal WO3–tetragonal SnO2 composite nanorods were formed. The microstructural analysis revealed that the SnO2 coverage layers were in a polycrystalline feature. The elemental distribution analysis revealed that the SnO2 thin layers homogeneously covered the surfaces of the hexagonally structured WO3 nanorods. The WO3–SnO2 composite nanorods with the thinnest SnO2 coverage layer showed superior gas-sensing response to 100–1000 ppm acetone vapor compared to other composite nanorods investigated in this study. The substantially improved gas-sensing responses to acetone vapor of the hexagonally structured WO3 nanorods coated with the SnO2 coverage layers are discussed in relation to the thickness of SnO2 coverage layers and the core–shell configuration of the WO3–SnO2 composite nanorods.

Hollow carbon spheres/hollow carbon nanorods composites as electrode materials for supercapacitor

Carbon-based materials with different morphologies have special properties suitable for application in adsorption, catalysis, energy storage and so on. Carbon composites consisting of different morphologies are proved to improve the performance due to combination of favorable structural features. In this work, hollow carbon spheres/hollow carbon nanorods (HCS/HCR) composites are prepared by “dissolution–reassembly” combined with hard template method. Taking advantage of compositional inhomogeneity of 3-aminophenol/formaldehyde (3-AF) resin sphere, 3-AF oligomers are obtained by dissolution of resin sphere with acetone and then used to reassemble with silica oligomer on MnO2 nanorods template under the function of CTAB to form HCS/HCR composites after carbonization and removing template. The obtained HCS/HCR composites with combined characteristics of hollow sphere and hollow nanorod exhibit high surface area (1590 m2 g−1), large pore volumes (2.4 cm3 g−1), and uniform pore size distribution (9.3 nm). When used as electrode material, the obtained HCS/HCR composites show good specific capacitance of 250 F g−1 at a current density of 1 A g−1 in 6 M KOH aqueous electrolyte solution, as well as good cycling stability (91.3% capacity retention after 5000 cycles), suggesting that the HCS/HCR composites electrode materials have potential applications in high-performance supercapacitor.

Effect of Au nanoparticles and Au mesostars on the photocatalytic activity of ZnO nanorods

The major drawback of Zinc Oxide (ZnO) as a photocatalyst is high recombination rate. The composite ZnO nanorods (NRs) with noble metal particles is a promising structure for reduction of recombination rate. In this study, we compare the effect of Au nanoparticles (NPs) with a diameter of 20–40 nm and the Au mesostars (MSs) with a size of 100–500 nm on the photocatalytic properties of ZnO nanorods. The electron-rich sites in sharp branches of Au Mss are expected to increase the photocatalytic activity. The results show that the addition of Au NPs enhances the degradation rate of methylene blue from 30% to 40%, while the addition of Au MSs actually reduced the activity to 28%. It maybe due to the eroded ZnO NR’s surface during the deposition of Au MSs, hence the whole of surface area of ZnO NRs is decreased. The electron transfer from ZnO to Au MSs indicated in PL spectrum does not seem to be enough to compensate the production of photogenerated electrons and holes in the sharp branches of Au mesostars.

Phase transition and changing properties of nanostructured V2O5 thin films deposited by spray pyrolysis technique, as a function of tungsten dopant

To investigate their formation mechanism and basic electronic behaviors, in this study undoped and tungsten (W)-doped vanadium oxide films were comparatively analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, photoluminescence (PL) and UV–Vis spectroscopy. The XRD measurement showed that the W doping causes a change in crystalline phase, improvement of grain size, a decrease in dislocation and stress with different dopant ratios. The SEM and AFM images evidenced that the W-doped films change nanostructured form from nanorods to composition of nanorods and nanoplates at 400 °C, which is 20% lower than general formation temperature of vanadium pentoxide (V2O5) nanorods, while the undoped film have small-sized nanostructural morphology as an initial stage. The Raman spectrum also indicates significant changes of its structural and optical properties. The PL quenching is observed in the PL spectra of the W-doped V2O5 films with decreasing deep-level emission. Band gap, Urbach energy, reflective index and dielectric constant of all the films were calculated by data of the UV–Vis and reflectance measurements. The results showed that the W-doped V2O5 films were more suitable for (opto)electronic device applications such as solar cell, gas sensor, electrochromic electrode and battery.

Mn3O4@NC Composite Nanorods as a Cathode for Rechargeable Aqueous Zn‐Ion Batteries

AbstractRechargeable aqueous zinc‐ion batteries (ZIBs) have attracted escalating attention recently, owing to their energy density, decreasing cost, advanced safety, and environmental benignity. Nevertheless, ZIBs still lack suitable cathode materials with stable cycling performance, owing to the high polarization of zinc ion. Therefore, developing candidate materials with excellent properties remains a great challenge. Herein, we successfully synthesize a novel Mn3O4@N‐doped carbon matrix composite nanorods (Mn3O4@NC Nrs) by using MnOOH nanorods (the self‐sacrifice templates) and polypyrrole (carbon and nitrogen source). Benefiting from the N‐doped carbon shell and the synergetic effect of Zn2+ and Mn2+ in the electrolyte, the Mn3O4@NC Nrs show superior cycling stability and long cycling features for ZIBs. Specifically, the zinc cell conducts a high reversible capacity of 280 mAh g−1 at 100 mA g−1 and retains a high reversible capacity of 97 mAh g−1 at 1000 mA g−1 after 700 cycles. In addition, the work provides a new approach to fabricate long‐term and high‐rate capability cathodes for ZIBs.