Hydrothermal Synthesis of Zn2SnO4 as Anode Materials for Li-Ion Battery

Effect of the Seed Layer on the Growth and Charge Transfer Behavior of Zn2SnO4 Nanorods in Photoelectrochemical Water Splitting

The growth of Zn2SnO4 nanorods on two differently prepared ZnO seed layers is demonstrated using a hydrothermal approach. The ZnO seed layers are prepared using dip-coating and electrodeposition techniques. The grown Zn2SnO4 nanorods are in the cubic phase. However, the different seed layers result in alternation in the diameter of grown Zn2SnO4 nanorods. The photocurrent of Zn2SnO4 nanorods grown on an electrodeposited ZnO seed layer is ∼4.5 times larger than that of Zn2SnO4 grown on a dip-coated ZnO seed layer. The Nyquist plots of Zn2SnO4 nanorods on the electrodeposited ZnO seed layer result in a lower charge transfer resistance (Rct = 37.7 Ω) and a lower bulk resistance (Rbulk = 64 kΩ), improving the charge transport properties. The change in diameter of Zn2SnO4 nanorods significantly alters the charge transfer behavior. The calculated charge injection efficiency did not exhibit a significant change. However, there was a 1.6-fold enhancement observed in the charge separation efficiency for Zn2SnO4 when grown on an electrodeposited seed layer.

In situ synthesis of advantageously united copper stannate nanoparticles for a new high powered supercapacitor electrode

A novel CuNi2O4@SnS@rGO/NF multicomponent hybrid material leads to fast ion/electron transfers at the electrode/electrolyte interface.

Thermal Evaporation Synthesis of Vertically Aligned Zn2SnO4/ZnO Radial Heterostructured Nanowires Array

The construction of a heterostructured nanowires array allows the simultaneous manipulation of the interfacial, surface, charge transport, and transfer properties, offering new opportunities to achieve multi-functionality for various applications. Herein, we developed facile thermal evaporation and post-annealing method to synthesize ternary-Zn₂SnO₄/binary-ZnO radially heterostructured nanowires array (HNA). Vertically aligned ZnO nanowires array (3.5 μm in length) were grown on a ZnO-nanoparticle-seeded, fluorine-doped tin oxide substrate by a hydrothermal method. Subsequently, the amorphous layer consisting of Zn-Sn-O complex was uniformly deposited on the surface of the ZnO nanowires via the thermal evaporation of the Zn and Sn powder mixture in vacuum, followed by post-annealing at 550 °C in air to oxidize and crystallize the Zn₂SnO₄ shell layer. The use of a powder mixture composed of elemental Zn and Sn (rather than oxides and carbon mixture) as an evaporation source ensures high vapor pressure at a low temperature (e.g., 700 °C) during thermal evaporation. The morphology, microstructure, and charge-transport properties of the Zn₂SnO₄/ZnO HNA were investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. Notably, the optimally synthesized Zn₂SnO₄/ZnO HNA shows an intimate interface, high surface roughness, and superior charge-separation and -transport properties compared with the pristine ZnO nanowires array.

Structural, optical, photocatalytic, and optoelectronic properties of Zn2SnO4 nanocrystals prepared by hydrothermal method

Zn₂SnO₄ (ZTO) nanocrystals are extensively studied in various fields. However, size-dependent ZTO nanocrystals are still challenging to understand their structural, optical, photocatalytic, and optoelectronic properties. ZTO nanocrystals are synthesized by a facile hydrothermal reaction method. The structural properties of the synthesized ZTO nanocrystals are studied by x-ray diffraction and transmission electron microscope. The sizes of the ZTO nanocrystals are controlled by the pH values of the precursor and the molar ratios of the Zn:Sn in the starting materials. ZTO nanocrystals with the small size of 6 nm and large size of 270 nm are obtained by our method. The Eu³⁺ ions are doped into ZTO nanocrystals to probe size-dependent Eu doping sites, which shows significant potential applications in light emitting diode phosphors. Moreover, the photocatalytic activity of ZTO nanocrystals on rhodamine (RhB) decoloration are investigated, and the results show that 6 nm ZTO nanocrystals show better performance in the photocatalytic decoloration of RhB compared to 270 nm nanocrystals. Most importantly, we design and fabricate optoelectronic devices to detect IR light based on our nanocrystals and a self-prepared NIR cyanine dye. The device based on small sized ZTO nanocrystals exhibits better device performance under 808 nm IR light compared to that of the large sized ZTO nanocrystals. We believe this work represents ZTO size-dependent properties in term of structural, optical, photocatalytic, and optoelectronic properties as a multifunctional material.

Pressure-induced Pb-Pb bonding and phase transition in Pb2SnO4

High-pressure single-crystal to 20 GPa and powder diffraction measurements to 50 GPa, show that the structure of Pb₂SnO₄ strongly distorts on compression with an elongation of one axis. A structural phase transition occurs between 10 GPa and 12 GPa, with a change of space group from Pbam to Pnam. The resistivity decreases by more than six orders of magnitude when pressure is increased from ambient conditions to 50 GPa. This insulator-to-semiconductor transition is accompanied by a reversible appearance change from transparent to opaque. Density functional theory-based calculations show that at ambient conditions the channels in the structure host the stereochemically-active Pb 6s² lone electron pairs. On compression the lone electron pairs form bonds between Pb²⁺ ions. Also provided is an assignment of irreducible representations to the experimentally observed Raman bands.

The hydrothermal synthesis of ZnSn(OH)6 and Zn2SnO4 and their photocatalytic performances

The pH value and hydrothermal temperature played an important part in the transition between ZnSn(OH)₆ and Zn₂SnO₄.

Electrochemical detection of 2-nitroaniline at a novel sphere-like Co2SnO4 modified glassy carbon electrode

A novel electrochemical sensor, based on a Co₂SnO₄ (CoSnO) modified glassy carbon electrode (GCE), has been successfully developed for the determination of 2-nitroaniline (2-NA).

Embedding ultrafine ZnSnO3 nanoparticles into reduced graphene oxide composites as high-performance electrodes for lithium ion batteries

Ultrafine ZnSnO₃ nanoparticles, with an average diameter of 45 nm, homogeneously grown on reduced graphene oxide (rGO) have been successfully fabricated via methods of low temperature coprecipitation, colloid electrostatic self-assembly, and hydrothermal treatment. The uniformly distributed ZnSnO₃ nanocrystals could inhibit the restacking of rGO sheets. In turn, the existence of rGO could hinder the growth and aggregation of ZnSnO₃ nanoparticles in the synthesis process, increase the conductivity of the composite, and buffer the volume expansion of the ZnSnO₃ nanocrystals upon lithium ion insertion and extraction. The obtained ZnSnO₃/rGO exhibited superior cycling stability with a discharge/charge capacity of 718/696 mA h g^-1 after 100 cycles at a current density of 0.1 A g^-1.

High rate performance SnO2based three-dimensional graphene composite electrode for lithium-ion battery applications

A composite of SnO₂and three-dimensional graphene (SnO₂/3DG) was fabricated using a hydrothermal method, with polystyrene balls (PS) as templates, and was found to have excellent electrochemical performance..

Advanced High Energy Density Secondary Batteries with Multi-Electron Reaction Materials

Secondary batteries have become important for smart grid and electric vehicle applications, and massive effort has been dedicated to optimizing the current generation and improving their energy density. Multi-electron chemistry has paved a new path for the breaking of the barriers that exist in traditional battery research and applications, and provided new ideas for developing new battery systems that meet energy density requirements. An in-depth understanding of multi-electron chemistries in terms of the charge transfer mechanisms occuring during their electrochemical processes is necessary and urgent for the modification of secondary battery materials and development of secondary battery systems. In this Review, multi-electron chemistry for high energy density electrode materials and the corresponding secondary battery systems are discussed. Specifically, four battery systems based on multi-electron reactions are classified in this review: lithium- and sodium-ion batteries based on monovalent cations; rechargeable batteries based on the insertion of polyvalent cations beyond those of alkali metals; metal-air batteries, and Li-S batteries. It is noted that challenges still exist in the development of multi-electron chemistries that must be overcome to meet the energy density requirements of different battery systems, and much effort has more effort to be devoted to this.

Optimized Zn2SnO4 nanoparticles with enhanced performance for photodetectors and photocatalysts

Zn₂SnO₄ nanoparticles with different sizes are successfully synthesized by a very convenient hydrothermal process. Moreover, the photocurrent response and photocatalytic activity properties of them have been studied in detail.

An overview of AB2O4- and A2BO4-structured negative electrodes for advanced Li-ion batteries

Energy-storage devices are state-of-the-art devices with many potential technical and domestic applications.

Combined flame and solution synthesis of nanoscale tungsten-oxide and zinc/tin-oxide heterostructures

Heterostructures of tungsten-oxide nanowires decorated with zinc/tin-oxide nanostructures are synthesized via a combined flame and solution synthesis approach. Vertically well-aligned tungsten-oxide nanowires are grown on a tungsten substrate by a flame synthesis method. Here, tetragonal WO(2.9) nanowires (diameters of 20-50 nm, lengths >10 μm, and coverage density of 10(9)-10(10) cm(-2)) are produced by the vapor-solid mechanism at 1720 K. Various kinds of Zn/Sn-oxide nanostructures are grown or deposited on the WO(2.9) nanowires by adjusting the Sn(2+) : Zn(2+) molar ratio in an aqueous ethylenediamine solution at 65 °C. With WO(2.9) nanowires serving as the base structures, sequential growth or deposition on them of hexagonal ZnO nanoplates, Zn(2)SnO(4) nanocubes, and SnO(2) nanoparticles are attained for Sn(2+) : Zn(2+) ratios of 0 : 1, 1 : 10, and 10 : 1, respectively, along with different saturation conditions. High-resolution transmission electron microscopy of the interfaces at the nanoheterojunctions shows abrupt interfaces for ZnO/WO(2.9) and Zn(2)SnO(4)/WO(2.9), despite lattice mismatches of >20%.

Facile Synthesis of Porous Zn-Sn-O Nanocubes and Their Electrochemical Performances

Porous Zn-Sn-O nanocubes with a uniform size were synthesized through a facile aqueous solution route combined with subsequent thermal treatment. The chemical composition, morphology, and microstructure of Zn-Sn-O nanocubes, which have significant effects on the lithium storage performances, were easily tuned by adjusting the calcination temperature in preparation processes of ZnSn(OH)6 solid nanocubes. Further studies revealed that porous Zn-Sn-O nanocubes prepared at 600 °C exhibited a good rate capability and a high reversible capacity of 700 mAh g-1 at a current density of 200 mA g-1 after 50 cycles, which may be a great potential as anode materials in Lithium-ion batteries.

Formation of core-shell-structured Zn2SnO4-carbon microspheres with superior electrochemical properties by one-pot spray pyrolysis

Core-shell structured Zn2SnO4-carbon microspheres with different carbon contents are prepared by one-pot spray pyrolysis without any further heating process. A Zn2SnO4-carbon composite microsphere is prepared from one droplet containing Zn and Sn salts and polyvinylpyrrolidone (PVP). Melted PVP moves to the outside of the composite microsphere during the drying stage of the droplet. In addition, melting of the phase separated metal salts forms the dense core. Carbonization of the phase separated PVP forms the textured and porous thick carbon shell. The discharge capacities of the core-shell structured Zn2SnO4-carbon microspheres for the 2(nd) and 120(th) cycles at a current density of 1 A g(-1) are 864 and 770 mA h g(-1), respectively. However, the discharge capacities of the bare Zn2SnO4 microspheres prepared by the same process without PVP for the 2(nd) and 120(th) cycles are 1106 and 81 mA h g(-1), respectively. The stable and reversible discharge capacities of the Zn2SnO4-carbon composite microspheres prepared from the spray solution with 15 g PVP decrease from 894 to 528 mA h g(-1) as current density increases from 0.5 to 5 A g(-1).

Rationally designed hierarchical MnO2@NiO nanostructures for improved lithium ion storage

Hierarchical MnO₂@NiO nanostructures present 939 mA h g⁻¹ at 1 A g⁻¹ after 200 cycles which is higher than individual MnO₂ and NiO.

In situ and ex situ carbon coated Zn2SnO4 nanoparticles as promising negative electrodes for Li-ion batteries

Zinc stannate, Zn₂SnO₄ nanoparticles are successfully synthesized by a facile hydrothermal method.

Copper vanadates/polyaniline composites as anode materials for lithium-ion batteries

Constructed by a simple dip-and-dry process, Cu₅(VO₄)₂(OH)₄·H₂O/PANI and Cu₅V₂O₁₀/PANI core–shell nanocomposites exhibit excellent electrochemical performance as the anode materials in lithium-ion batteries.

Facile synthesis of Mn6.87(OH)3(VO4)3.6(V2O7)0.2 microtubes and their application as an anode material for lithium-ion batteries

Mn_6.87(OH)₃(VO₄)_3.6(V₂O₇)_0.2 microtubes have been fabricated by a simple one-step hydrothermal procedure.

Synthesis of curved Si flakes using Mg powder as both the template and reductant and their derivatives for lithium-ion batteries

Mg powder was used as both active template for SiO₂ shell coating and reductant to subsequently reduce SiO₂ sheaths into Si to obtain curved Si flakes for lithium storage.

Atomic-scale imaging of cation ordering in inverse spinel Zn2SnO4 nanowires

By using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with density functional theory (DFT) calculations, we demonstrate the atomic-level imaging of cation ordering in inverse spinel Zn2SnO4 nanowires. This cation ordering was identified as 1:1 ordering of Zn(2+) and Sn(4+) at the octahedral sites of the inverse spinel crystal with microscopic symmetry transition from original cubic Fd3̅m to orthorhombic Imma group. This ordering generated a 67.8% increase in the elastic modulus and 1-2 order of magnitude lower in the electric conductivity and electron mobility compared to their bulk counterpart.

Band gap tunable Zn2SnO4 nanocubes through thermal effect and their outstanding ultraviolet light photoresponse

This work presents a method for synthesis of high-yield, uniform and band gap tunable Zn₂SnO₄ nanocubes. These nanocubes can be further self-assembled into a series of novel nanofilms with tunable optical band gaps from 3.54 to 3.18 eV by simply increasing the heat treatment temperature. The Zn₂SnO₄ nanocube-nanofilm based device has been successfully fabricated and presents obviously higher photocurrent, larger photocurrent to dark current ratio than the previously reported individual nanostructure-based UV-light photodetectors, and could be used in high performance photodetectors, solar cells, and electrode materials for Li-ion battery.

CuGeO₃ nanowires covered with graphene as anode materials of lithium ion batteries with enhanced reversible capacity and cyclic performance

A facile one-step route was developed to synthesize crystalline CuGeO₃ nanowire/graphene composites (CGCs). Crystalline CuGeO₃ nanowires were tightly covered and anchored by graphene sheets, forming a layered structure. Subsequently, CGCs were exploited as electrode materials for lithium ion batteries (LIBs). The reversible formation of Li₂O buffer layer and elastic graphene sheets accommodated the volume change during the charge and discharge processes. CGC containing 37 wt% graphene exhibited a superior electrochemical performance, that is, a remarkable reversible capacity (1265 mA h g(-1) for the first cycle), an outstanding cyclic performance (853 mA h g(-1) after 50 cycles under a current density of 200 mA g(-1)), a high coulombic efficiency, and an excellent rate capability. Clearly, CGCs may stand out as a promising anode material for LIBs.

Selective formation of carbon-coated, metastable amorphous ZnSnO₃ nanocubes containing mesopores for use as high-capacity lithium-ion battery

Mesoporous and amorphous ZnSnO3 nanocubes of ~37 nm size coated with a thin porous carbon layer have been prepared using monodisperse ZnSn(OH)6 as the active precursor and low-temperature synthesized polydopamine as the carbon precursor. The small single nanocubes cross-link with each other to form a continuous conductive framework and interconnected porous channels with macropores of 74 nm width. Because of its multi-featured nanostructure, this material exhibits greatly enhanced integration of reversible alloying/de-alloying (i.e., transformation of Li(4.4)Sn and LiZn to Sn and Zn) and conversion (i.e., oxidation of Sn and Zn to ZnSnO3) reaction processes with an extremely high capacity of 1060 mA h g(-1) for up to 100 cycles. A high reversible capacity of 650 and 380 mA h g(-1) can also be delivered at rates of 2 and 3 A g(-1), respectively. This excellent electrochemical performance is attributed to the small particle size, well-developed mesoporosity, the amorphous nature of the ZnSnO3 and the continuous conductive framework produced by the interconnected carbon layers.

Effects of interface states on photoexcited carriers in ZnO/Zn(2)SnO(4) type-II radial heterostructure nanowires

Type-II band alignment of heterostructure contributes to spatially separate electrons and holes leading to an increase in minority carrier lifetime, which has much more advantages in photocatalytic activities and photovoltaic device applications. Here, Zn2SnO4-sheathed ZnO radial heterostructure nanowires were constructed to investigate systematically interfacial charge separation. The lattice mismatch between ZnO and Zn2SnO4 induces interface states to exist at their heterointerface. At low pump fluence, photoexcited charges are localized within the ZnO core rather than separated due to the large interface barrier. Correspondingly, only ZnO-related bandedge ultraviolet (UV) and green emissions are dominated in photoluminescence spectra. At high pump fluence, however, impurities are ionized and electrons trapped in interface states are excited, resulting in a decrease in interface barrier, which makes photogenerated charges efficiently separated at their heterointerface by direct tunneling, and, consequently, an additional blue-violet emission, attributed to the heterointerface recombination of electrons in Zn2SnO4 conduction band (CB) and holes in ZnO valence band. Additionally, the heterointerface can separate effectively photoexcited carriers and form a photovoltaic effect. Our results provide the localization/separation condition of photogenerated charges for the type-II band alignment of core/shell heterostructure, which should be very useful for the realization of underpinned mechanism of the developed optoelectronic devices.

Zn2SiO4urchin-like microspheres: controlled synthesis and application in lithium-ion batteries

Three-dimensional Zn₂SiO₄urchin-like microspheres have been fabricated by a one-step hydrothermal procedure.

Surfactant-free synthesis of Zn2SnO4 octahedron decorated with nanoplates and its application in rechargeable lithium ion batteries

We demonstrate the fabrication of a Zn₂SnO₄ octahedron decorated with nanoplates via a facile surfactant-free hydrothermal method.

Zn2SnO4 nanowires versus nanoplates: electrochemical performance and morphological evolution during Li-cycling

Zn2SnO4 nanowires have been synthesized directly on stainless steel substrate without any buffer layers by the vapor transport method. The structural and morphological properties are investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of Zn2SnO4 nanowires is examined by galvanostatic cycling and cyclic voltammetry (CV) measurements in two different voltage windows, 0.005-3 and 0.005-1.5 V vs Li and compared to that of Zn2SnO4 nanoplates prepared by hydrothermal method. Galvanostatic cycling studies of Zn2SnO4 nanowires in the voltage range 0.005-3 V, at a current of 120 mA g(-1), show a reversible capacity of 1000 (±5) mAh g(-1) with almost stable capacity for first 10 cycles, which thereafter fades to 695 mAh g(-1) by 60 cycles. Upon cycling in the voltage range 0.005-1.5 V vs Li, a stable, reversible capacity of 680 (±5) mAh g(-1) is observed for first 10 cycles with a capacity retention of 58% between 10-50 cycles. On the other hand, Zn2SnO4 nanoplates show drastic capacity fading up to 10 cycles and then showed a capacity retention of 80% and 70% between 10 and 50 cycles when cycled in the voltage range 0.005-1.5 and 0.005-3 V, respectively. The structural and morphological evolutions during cycling and their implications on the Li-cycling behavior of Zn2SnO4 nanowires are examined. The effect of the choice of voltage range and initial morphology of the active material on the Li-cycleabilty is also elucidated.