New routes towards the formation of tin oxide inverted opals for charge storage applications

New routes to formation of tin oxide inverted opals with unique morphologies are presented. Inverted opals with walls formed from assemblies of tin oxide nanocrystals are formed from tin acetate precursor, while mesoporous walls are formed when tin alkoxide precursors are used. The inverted opals are investigated by a variety of techniques in order to determine their structure and the dependence of electrochemical properties on the type of precursor used. We found that the initial discharge capacity of the inverted opal based batteries reaches 1200 mAhg-1 but quickly fades afterwards, as it is typical for tin oxide based anodes. Careful investigation of processes occurring in the tin oxide inverted opal anodes may lead to improvement of their performance improvement, and further development of self-supported tin oxide based anodes

Structuring materials for Lithium-ion batteries: Advancements in nanomaterial structure, composition, and defined assembly on cell performance

This review outlines the developments in the structure, composition, size, and shape control of many important and emerging Li-ion battery materials on many length scales, and details very recent investigations on how the assembly and programmable order in energy storage materials have not only influenced and dramatically improved the performance of some Li-ion batteries, but offered new routes toward improved power densities. This review also describes and discusses material aspects of hybrid and multiphasic materials including silicon, germanium, a wide range of metal oxides, alloys and crystal structures, carbons and other important materials. Methods including engineered porosity that offer the energy density of Li-ion batteries and the power density of pseudocapacitors are also highlighted. Recent developments in the analytical methods, electrochemical response, and the structure, composition, size, shape and defined assembly of active materials for a wide range of Li-ion cathodes and anodes are compared and assessed with respect to cell performance. Perspectives on the future development of energy storage materials based on structure as well as chemistry are also outlined

Investigations into structure and chemistry of 1D, 2D and 3D structured vanadium oxide nanomaterials for Li-ion batteries

Routes towards the formation of inverted opal vanadium oxide electrodes are presented. Different methods of template infiltration using an IPA diluted solution of vanadium triisopropoxide are discussed and the resulting morphologies investigated using scanning electron microscopy. The effect of different heat treatments and method of sphere removal on morphology and structure is also considered. Solvent template removal retains thehydrolysed amorphous V2O5 structure. Raman scattering spectroscopy identifies the degree of V2O5 crystallinity that results from the different heat treatments. For a thicker inverted opal formed using a polystyrene template as opposed to a monolayer PMMA template, under similar conditions a different phase of vanadium oxide is observed evident by variations inRaman scattering response

Synthetic routes for the preparation of ordered vanadium oxide inverted opal electrodes for Li-ion batteries.

Synthetic routes for the formation of opal assemblies as templates for the inverted opal vanadium oxide electrodes are presented. A method for the formation of monolayer opal templates on gold substrates is discussed and the formation of multilayer opal templates on conductive substrates by electrophoretic deposition is also described, with order defined by angle resolved light scattering measurements. Inverted opals are formed from a diluted solution of IPA and vanadium alkoxide precursor, infiltrated into the templates by several methods. The effect of different heat treatments and method of polymer template removal on the resulting inverse opal morphology and structure is investigated

Light scattering investigation of 2D and 3D opal template formation on hydrophilized surfaces.

We demonstrate the formation of 2D photonic crystals (opals) on gold coated silicon substrates by dip-coating at a high rate of 1 mm/min when the surfactant sodium dodecyl sulphate (SDS) is added to the solution above its critical micelle concentration. The dependence of substrate hydrophillicity is demonstrated to influence the formation of 3D templates on glass substrates using 700 nm diameter PMMA spheres. Other routes towards directing opal assembly are also discussed. Angle-resolved reflectance shows 2D and 3D light scattering characteristics from the fast-rate dip-coated monolayer 2D 3D photonic crystals grown on hydrophillized glass respectively, with a high degree of surface ordering

Three-dimensionally ordered hierarchically porous tin dioxide inverse opals and immobilization of palladium nanoparticles for catalytic applications

A high surface area 3D ordered SnO2 inverted opal with walls composed of interconnected nanocrystals is reported using a facile approach with tin acetate precursors. The hierarchically porous structure exhibits porosity on multiple lengths scales (cm down to nm). The thickness of the IO wall structure comprising nanocrystals of the oxide can be tuned by multiple infilling of the precursor. Using highly monodisperse Pd nanoparticles, we show how the SnO2 IO can be functionalized with immobilized Pd NP assemblies. We show that the Pd NP size dispersion is controlled by utilizing weak ligand–metal interactions and strong metal-oxide interactions for the immobilization step. The resulting SnO2–Pd IOs were investigated X-ray photoelectron spectroscopy indicating electronic interactions between the Pd and SnO2 and alterations to NP surface chemistry. Pd NPs assembled with excellent dispersion on the ordered SnO2 IOs show superior catalytic performance for liquid phase chemical synthesis via Suzuki coupling reactions and allow easy removal of the catalyst substrate post reaction. Higher mass electrocatalytic activity is also demonstrated for formic acid oxidation, compared to commercial Pd/C catalysts, which is shown to be due to better access to the catalytically active sites on SnO2–Pd IOs. The high surface area interconnected phase-pure SnO2 IO, with programmable porosity forms a functional material for catalytic applications

Ordered 2D colloidal photonic crystals on gold substrates by surfactant-assisted fast-rate Dip coating

Surfactant induced ordering of 2D and 3D colloidal crystal photonic crystals is possible on metallic substrates by dip‐coating at fast rates (≈1 mm/min). Ordered monolayer opals on conductive gold‐coated silicon substrates behave as a 2D diffraction grating. The method allows high throughput, ordered colloidal crystal formation useful as nanomaterials templates for energy storage or functional materials

Core-shell tin oxide, indium oxide, and indium tin oxide nanoparticles on Si with tunable dispersion: Electrochemical and structural characteristics as a hybrid Li-ion battery anode

Tin oxide (SnO2) is considered a very promising material as a high capacity Li-ion battery anode. Its adoption depends on a solid understanding of factors that affect electrochemical behavior and performance such as size and composition. We demonstrate here, that defined dispersions and structures can improve our understanding of Li-ion battery anode material architecture on alloying and co-intercalation processes of Lithium with Sn from SnO2 on Si. Two different types of well-defined hierarchical Sn@SnO2 core–shell nanoparticle (NP) dispersions were prepared by molecular beam epitaxy (MBE) on silicon, composed of either amorphous or polycrystalline SnO2 shells. In2O3 and Sn doped In2O3 (ITO) NP dispersions are also demonstrated from MBE NP growth. Lithium alloying with the reduced form of the NPs and co-insertion into the silicon substrate showed reversible charge storage. Through correlation of electrochemical and structural characteristics of the anodes, we detail the link between the composition, areal and volumetric densities, and the effect of electrochemical alloying of Lithium with Sn@SnO2 and related NPs on their structure and, importantly, their dispersion on the electrode. The dispersion also dictates the degree of co-insertion into the Si current collector, which can act as a buffer. The compositional and structural engineering of SnO2 and related materials using highly defined MBE growth as model system allows a detailed examination of the influence of material dispersion or nanoarchitecture on the electrochemical performance of active electrodes and materials

Rechargeable Li-ion battery anode of indium oxide with visible to infra-red transparency

Unique bimodal distributions of single crystal epitaxially grown In2O3 nanodots on silicon are shown to have excellent IR transparency greater than 87% at 4 μm without sacrificing transparency in the visible region. These broadband antireflective nanodot dispersions are grown using a two-step metal deposition and oxidation by molecular beam epitaxy, and backscattered diffraction confirms a dominant (111) surface orientation. We detail the growth of a bimodal size distribution that facilitates good surface coverage (80%) while allowing a significant reduction in In2O3 refractive index. The (111) surface orientation of the nanodots, when fully ripened, allows minimum lattice mismatch strain between the In2O3 and the Si surface. This helps to circumvent potential interfacial weakening caused by volume contraction due to electrochemical reduction to lithium, or expansion during lithiation. Cycling under potentiodynamic conditions shows that the transparent anode of nanodots reversibly alloys lithium with good Coulombic efficiency, buffered by co-insertion into the silicon substrate. These properties could potentially lead to further development of similarly controlled dispersions of a range of other active materials to give transparent battery electrodes or materials capable of non-destructive in-situ spectroscopic characterization during charging and discharging

Semiconductor nanostructures for antireflection coatings, transparent contacts, junctionless thermoelectrics and Li-ion batteries

Porous semiconductors structured top-down by electrochemical means, and from bottom-up growth of arrays and arrangements of nanoscale structures, are shown to be amenable to a range of useful thermal, optical, electrical and electrochemical properties. This paper summarises recent investigations of the electrochemical, electrical, optical, thermal and structural properties of porous semiconductors such as Si, In2O3, SnO2 and ITO, and dispersions, arrays and arrangements of nanoscale structures of each of these materials. We summarize the property-inspired application of such structurally engineered arrangements and morphologies of these materials for antireflection coatings, broadband absorbers, transparent contacts to LEDs that improve transmission, electrical contact and external quantum efficiency. Additionally the possibility of thermoelectric performance through structure-mediated variation in thermal resistance and phonon scattering without a p-n junction is shown through phonon engineering in roughened nanowires. Lastly, we show that bulk crystals and nanowires of p- and n-type doped Si are promising for use as anodes in Li-ion batteries