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Fe-doped Co3O4 (Fe–Co3O4) increases the specific surface area and introduces oxygen defects, thus promoting redox reactions and improving capacity also cycle stability.

Vanadium-based oxide is widely investigated as a zinc ion battery (ZIB) cathode due to its ability to react reversibly with Zn

Highlights Bi2S3 is proposed as a promising cathode material for rechargeable aqueous Zn ion battery.The Zn/Bi2S3 battery shows a reversible capacity of 161 mAh g−1 at 0.2 A g−1 and good cyclic stability of up to 100 cycles with ca. 100% retention.The storage mechanism in the Bi2S3 cathode is related to the reversible Zn ion intercalation/extraction reactions and the capacitive contribution. Electronic supplementary material The online version of this article (10.1007/s40820-019-0352-3) contains supplementary material, which is available to authorized users., Aqueous Zn ion batteries (ZIBs) are promising in energy storage due to the low cost, high safety, and material abundance. The development of metal oxides as the cathode for ZIBs is limited by the strong electrostatic forces between O2− and Zn2+ which leads to poor cyclic stability. Herein, Bi2S3 is proposed as a promising cathode material for rechargeable aqueous ZIBs. Improved cyclic stability and fast diffusion of Zn2+ is observed. Also, the layered structure of Bi2S3 with the weak van der Waals interaction between layers offers paths for diffusion and occupancy of Zn2+. As a result, the Zn/Bi2S3 battery delivers high capacity of 161 mAh g−1 at 0.2 A g−1 and good cycling stability up to 100 cycles with ca. 100% retention. The battery also demonstrates good cyclic performance of ca. 80.3% over 2000 cycles at 1 A g−1. The storage mechanism in the Bi2S3 cathode is related to the reversible Zn ion intercalation/extraction reactions and the capacitive contribution. This work indicates that Bi2S3 shows great potential as the cathode of ZIBs with good performance and stability. Electronic supplementary material The online version of this article (10.1007/s40820-019-0352-3) contains supplementary material, which is available to authorized users.

Organic compounds, such as polyvinylidene fluoride (PVDF), have been widely used as a binder in battery electrode preparations. While such an approach does not have a significant impact on the performance of the batteries that utilize low valence ions, such as the Li ion battery (LIB), the diffusion of high valence ions (such as Zn

It is a key to develop novel electrode materials with high energy and power density for advanced batteries to meet the demand of electric vehicles (EVs). Manganese cobalt oxides which can react with a large number of ions from the electrolyte for electrochemical energy storage are developing into the promising electrode materials. In this work, well-ordered MnCo2O4.5 nanorod arrays (MCO NRAs) are prepared on Ni foam by a general route of hydrothermal growth and low-temperature annealing treatment. The samples deliver a high initial capacity of 1402.6 mAh g-1 at the current density of 100 mA g-1 and rate capacity of 528 mAh g-1 when the current density is improved 10 times as binder-free anodes for Li-ion batteries (LIBs). After 60 cycles at the current density of 200 mA g-1, the MnCo2O4.5 nanorods still achieve 603 mAh g-1 with capacity retention of 66% (compared with the second discharge capacity). The superior electrochemical properties are due to the fascinating architecture which increases the reaction area and structural stability, reduces ion and electron transport distance and provides good strain release. Hence, MnCo2O4.5 nanorod arrays are promised as advanced anodes for future LIBs with completely meeting the demand of EVs.

In this study, hierarchical SnO2@MOx (SnO2@NiO, SnO2@Co3O4, and SnO2@MnO2) heterostructures grown on carbon cloth (CC) for high performance supercapacitors were fabricated by a two-step solution-based method involving a hydrothermal process and a chemical bath deposition, which utilizes the better electronic conductivity of SnO2 nanosheets as the supporting backbone to deposit MOx for supercapacitor electrodes. Particularly, the as-formed SnO2@MOx heterostructure electrodes showed better electrochemical performance than bare SnO2 nanosheets. Remarkably, the SnO2@MnO2 heterostructure electrode showed the highest discharge areal capacitance (980 mF cm−2 at 1 mA cm−2), good rate capability (still 767 mF cm−2 at 20 mA cm−2), and excellent cycling stability (∼21.9% loss after 6000 repetitive cycles at a charge–discharge current density of 1 mA cm−2). The enhanced pseudocapacitive performance was mainly attributed to its unique hybrid structure, which provides fast ion and electron transfer, a large number of active sites, and good strain accommodation. The excellent electrochemical performance of the as-obtained heterostructures will undoubtedly make these hybrid structures attractive for high performance supercapacitors with high power and energy densities.

Heterostructured ZnO/ZnS nanoforests are prepared through a simple two-step thermal evaporation method at 650 °C and 1300 °C in a tube furnace under the flow of argon gas, respectively. A metal catalyst (Au) to form a binary alloy has been used in the process. The as-obtained ZnO/ZnS products are characterized by using a series of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion X-ray spectroscopy (EDS), Raman spectroscopy and photoluminescence. A possible growth mechanism is temporarily proposed. The hybrid structures are also directly functionalized as supercapacitor (SC) electrodes without using any ancillary materials such as carbon black or binder. Results show that the as-synthesized ZnO/ZnS heterostructures exhibit a greatly reduced ultraviolet emission and dramatically enhanced green emission compared to pure ZnO nanorods. The SCs data demonstrate high specific capacitance of 217 mF cm(-2) at 1 mA cm(-2) and excellent cyclic performance with 82% capacity retention after 2000 cycles at a current density of 2.0 mA cm(-2).

In this paper, large scale CdS nanospheres are synthesized via a facile and effective hydrothermal route. Through an inspection of the morphologies under various growth conditions, a possible growth mechanism for CdS nanospheres was proposed, which involves a nuclei aggregation and an Ostwald ripening process. The as- prepared CdS nanospheres exhibit superior photocatalytic activities by the photodegradation of eosin red, Congo red (CR) and methylene blue (MB) under visible light irradiation, with a comparison with the other CdS nanostructures, P25 and α-Fe2O3 powders. It demonstrates potential applications in removal of organic dye molecules from waste water.

Hybrid α-Fe2O3@NiO heterostructures are successfully anchored on a carbon cloth by a facile hydrothermal approach. α-Fe2O3 nanorods are used as the conducting scaffolds to support NiO nanosheets. The as-prepared heterostructures are characterized by series of techniques and directly functionalized as the supercapacitors (SCs) without using any ancillary materials such as carbon black or the binders. The SCs demonstrate high areal capacitance of 557 mF/cm2 and excellent cyclic performance with nearly 96.2% capacity retention after 3000 cycles at a current density of 1 mA/cm2. The excellent electrochemical performance can be attributed to a rational combination of two electrochemical active materials. Besides, the hybrid heterostructure can be used as a high performance recyclable photocatalyst under visible light irradiation, which can photodegrade Congo red (CR) with the degradation rate of 98% after 30 min, it demonstrates potential applications in wastewater treatment and energy storage devices.

This paper reports the successful synthesis, structural and optical characterizations of ultra-long germanium oxide (GeO 2 ) nanowires. The ultra-long GeO 2 nanowires were synthesized by facile and simple thermal evaporation process using high-purity Ge powder on Au/Si substrate at 1200 °C. The prepared nanowires were investigated by various techniques in terms of their morphological, structural, compositional and optical properties. By detailed morphological, structural and compositional studies, it is confirmed that the prepared GeO 2 nanowires are pure, grown in very high density, and possessing well-crystallinity. A VLS growth mechanism is proposed for the formation of as-prepared GeO 2 nanowires. The optical properties of the as-prepared nanowires were conducted by room-temperature photoluminescence (PL), revealing that the nanowires exhibited a prominent UV emission peak centered at 411 nm and a weak green emission peak at 526 nm, and hence demonstrating good optical properties with fewer deep-level defects.

In this paper, large scale uniform α-Fe2O3 nanocubes are synthesized through a facile and effective hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM). A possible growth mechanism for α-Fe2O3 nanocubes is proposed based on the experimental results. Photocatalytic test reveals that Congo red can be degraded nearly completely (over 95%) after visible light irradiation of 40 min. In addition, methyl orange and methylene blue aqueous solution degradation experiments also are conducted in the same condition, revealing the versatile potential applications of the product in wastewater purifications.

alpha-Fe2O3 nanorods are controlled prepared by a facile hydrothermal process followed by a calcination treatment. The experiment results indicate that the morphology of the as-obtained product depends greatly on the quantity of NaOH. The photocatalytic performances of the as-prepared samples were evaluated by photocatalytic decolorization of Congo red solution at ambient temperature. The results indicate that the photocatalytic activity of the alpha-Fe2O3 nanorods is superior to alpha-Fe2O3 nanoparticles and microplates, revealing the versatile potential applications of the product in wastewater purifications.

Novel SnO 2 assembles by many nanosheets are successfully synthesized on a flexible carbon cloth through a chemical vapor deposition (CVD) method at 750 °C. The as-prepared products are characterized by using a series of test techniques, including scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectrum and the spectrophotometer. A possible growth mechanism is temporarily proposed. Photoluminescence (PL) spectrum of the as-prepared SnO 2 product shows a weak blue emission peak at 436 nm and a strong green emission peak centered at 526 nm, which may be ascribed to the defects associated with the structures.

We have synthesized high-quality, nanoscale ultrathin ZnO films at relatively low temperature using a facile and effective hydrothermal approach. ZnO films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, photoluminescence spectra (PL), and UV-vis absorption spectroscopy. The products demonstrated 95% photodegradation efficiency with Congo red (CR) after 40 min irradiation. The photocatalytic degradation experiments of methyl orange (MO) and eosin red also were carried out. The results indicate that the as-obtained ZnO films might be promising candidates as the excellent photocatalysts for elimination of waste water.

A simple hydrothermal route was developed for the synthesis of uniform α-MnO2 nanowires using a controllable redox reaction in a MnCl2–KMnO4 aqueous solution system. Electrochemical properties of the resulting products as an electrode were investigated by cyclic voltammetry, chronopotentiometry and electrochemical impedance tests. The electrode can provide a specific capacitance of 180 F g−1 at a current density of 1.0 A g−1. After 2000 cycles, the specific capacitance was maintained above 78%. Besides, the as-synthesized products were also used as the photocatalyst for the photocatalytic degradation of several dye molecules. The results show almost complete degradation (~99%) of Congo red dye molecules in 30 min. Such ultralong MnO2 nanowires are expected to have potential applications in wastewater treatment and energy storage.

In this work, ZnO nanorods are obtained through a facile hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental results indicated that the as-synthesized ZnO nanorods have an average diameter of approximate 100 nm. A possible growth mechanism for ZnO nanorods was proposed based on the experimental results and found that Zn powder plays a critical role for the morphology of the products. Room temperature photoluminescence property of ZnO nanorods shows an ultraviolet emission peak at 390 nm.

Large-scale uniform ZnO nanotowers on silicon substrate have been prepared by the thermal evaporation method at 950°C using Au as the catalyst. The morphology and microstructure of the as-synthesised ZnO nanotowers were characterised by scanning electron microscopy and X-ray diffraction. The room temperature photoluminescence spectrum of the as-synthesised ZnO nanotowers shows a strong ultraviolet emission peak at 380 nm and a weak green emission at 540 nm, revealing that there are a few deep-level defects in the single ZnO structure. The growth mechanism of the as-synthesised ZnO structures is also discussed.

α-Fe2O3 nanorods are controlled prepared by a facile hydrothermal process followed by a calcination treatment. The experiment results indicate that the morphology of the as-obtained product depends greatly on the quantity of NaOH. The photocatalytic performances of the as-prepared samples were evaluated by photocatalytic decolorization of Congo red solution at ambient temperature. The results indicate that the photocatalytic activity of the α-Fe2O3 nanorods is superior to α-Fe2O3 nanoparticles and microplates, revealing the versatile potential applications of the product in wastewater purifications.

In this paper, large scale uniform α-Fe2O3 nanocubes are synthesized through a facile and effective hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM). A possible growth mechanism for α-Fe2O3 nanocubes is proposed based on the experimental results. Photocatalytic test reveals that Congo red can be degraded nearly completely (over 95%) after visible light irradiation of 40 min. In addition, methyl orange and methylene blue aqueous solution degradation experiments also are conducted in the same condition, revealing the versatile potential applications of the product in wastewater purifications.

Uniform MnO2 nanorods were synthesized successfully via a facile and effective hydrothermal approach. Scanning electron microscope images showed that the average diameter of the as-synthesized nanorod is about 30 nm and the length of that is about 5 μm, respectively. Photocatalytic experimental results indicate that Congo red can be degraded nearly completely (over 97%) after visible light irradiation of 120 min, demonstrating potential applications of such nanorod structures for wastewater purification.

Large scale ZnO microflowers assembled by numerous nanosheets are synthesized through a facile and effective hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Photocatalytic properties of the as-synthesized products are also investigated. The results demonstrate that eosin red aqueous solution can be degraded over 97% after 110 min under UV light irradiation. In addition, methyl orange (MO) and Congo red (CR) aqueous solution degradation experiments also are conducted in the same condition, respectively. It showed that nanosheet-assembled ZnO microflowers represent high photocatalytic activities with a degradation efficiency of 91% for CR with 90 min of irradiation and 90% for MO with 60 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

Hierarchically assembled SnO2 microflowers were synthesized by a facile hydrothermal process. Field emission scanning electron microscope results showed these hierarchical nanostructures were built from two dimensional nanosheets with the thicknesses of about 50 nm. Photoluminescence spectrum of the as-obtained products demonstrated a strong visual emission peak at 564 nm. The photochemical measurement results indicated that the as-prepared sample exhibits excellent photocatalytic performance. These three dimensional SnO2 hierarchical nanostructures may have potential applications in waste water purification.

In this paper, for the first time, we report the synthesis of nanoscale cuprous chloride (CuCl) cubic structure by a facile hydrothermal route. A possible mechanism for the growth of those nanostructures is proposed based on the experimental results. It is discovered that the existence of HCl could affect the surface of CuCl nanocubes. This unique cube-like nanostructure with rough surface significantly enhances the electroactive surface areas of CuCl, leading to a high special capacitance of 376 mF cm−2 at the current density of 1.0 mA cm−2. There is still a good reversibility with cycling efficiency of 88.8 % after 2,000 cycles, demonstrating its excellent long-term cycling stability and might be the promising candidates as the excellent electrode material.