Spray-Assisted Method of Synthesis of Anode Materials for Lithium-Ion Battery

The current energy and environment challenges demand an emerging renewable energy sources and green electrical transportation implementation. Both of these require rechargeable batteries to store energy and provide power. However, lithium-ion batteries (LIBs) with graphite-based anode, which is the most used anode material for current LIB technologies, cannot meet the requirements for new generation electric vehicles of different type (hybrid, plug-in or pure) and other applications such as modern communication systems, because they require two to five times more energy density than what LIBs with graphite-based anode can offer. Thus, there is an extreme need for introduction of novel materials for next generation anode for LIBs. The spinel-structured lithium titanium oxide Li4Ti5O12 (LTO) is one of the most effective active matrices for silicon (Si) to form anode and enhance the advantageous properties of both materials. One of the possibilities to efficiently combine Si and LTO, keeping their advantages and overcoming drawbacks, is to apply nanomixing. Moreover, in order to enhance conductivity of the composite, sucrose and polyethylene glycol (PEG) were added into the material as a carbon source, and their effect on its electrochemical performance was compared. One of the most suitable and promising method of LTO synthesis is the spray pyrolysis technique as there are promising opportunities to establish a continuous preparation process

Simple Method to Synthesize Functionalized Carbon Nanotubes Employing Cobalt Nitrate and Acetone by Using Spray Pyrolysis Deposition Technique

Recently alcohols and ketones have been employed to sensitize CNT by CVD. A study has shown the importance of the chemical nature of those carbon precursors on the characteristics of the CNT (carbon nanotubes) obtained. In the present work we show the influence of the catalyst employed on the synthesis of functionalized multiwall carbon nanotubes (MWCNTs) utilizing acetone as carbon source and cobalt nitrate Co(NO3)2 as catalyst

Novel Nanostructured Materials for Solar Fuel Production and Advanced Rechargeable Batteries

Non-renewable fossil fuels are the major sources to meet the energy, electricity and transportation demands of today\u27s world. The over consumption of fossil fuels will lead to the increasing energy crisis and disastrous effects such as air pollution, global warming etc. The primary greenhouse gas is CO2 mainly emits from the combustion of fossil fuels. Photocatalytic reduction of CO2 using sunlight as the energy input is a promising way to reduce CO2 level in the atmosphere and in the meantime produce alternative fuels such as CO, methane, methanol, etc. Among the various photocatalyst materials reported, nanomaterial TiO2 is the most widely studied due to its suitable band positions, high chemical stability, non-toxic nature, and low cost. However, the energy conversion efficiency using TiO2 for CO2 photoreduction is still low, mainly due to the reasons of (1) high probability of recombination of photo-induced electron-hole pairs, (2) fast backward reaction of hydrogen and oxygen to form water, and (3) limited ability of visible light utilization. Another efficient way to decrease CO2 emissions is to reduce fossil fuels consumption. The invention of hybrid electric vehicles (HEVs) and electric vehicles (EVs) are great promise of replacing traditional gasoline driven automobiles. As one of the new generation high energy density batteries, lithium-sulfur (Li-S) battery is very attractive because sulfur has a high theoretical capacity of 1,675 mA h g-1. However, the practical realization of Li-S batteries is limited by several problems: (1) poor electrical conductivity of sulfur (2) dissolution of the lithium polysulfide intermediates into the electrolyte, and (3) large volume expansion of sulfur during cycling. One objective of this study is to demonstrate high-efficiency photocatalysts using innovative hybird nanostructures that consist of Ce doped TiO2 dispersed on mesoporous silica (SBA-15) or noble-metal nanoparticles Ag supported on TiO2 or MgAl-LDOs (layered double oxides) grafted on TiO2 (TiO2-MgAl LDOs). The use of Ce doping could result in smaller TiO2 nanocrystals and facilitate electron-hole separation, while SBA-15 provides good dispersion of TiO2 and a strong interaction between TiO2 and the substrate. And Ag species on TiO2 facilitate electron trapping and transport to the catalyst surface, and thus, can potentially enhance multi-electron transfer processes. TiO2-MgAl LDOs is favorable for CO2 species adsorption on the photocatalyst, therefore, compensating the weakened CO2 adsorption ability at higher temperature in the presence of H2O vapor. The other objective of this study is to find alternative materials as anode for Li-ion battries and demonstrate high-performance Li-S battery electrodes using hybrid nanomaterials consist of sulfur infiltrated porous micrsophere carbon (PMC). Carbon/TiO2 was found to be promising as anode alternative to replace graphite materials to avoid safety issues for Li-ion batteries. Cathodes made of sulfur infiltrated in such a multi-modal porous carbon framework provide advantageous properties that guaranttee the superior electrochemical performance. Ce-doped TiO2 on SBA-15, Ag deposited TiO2 (Ag/TiO2) and MgAl-LDOs grafted on TiO2 (TiO2-MgAl LDOs) were synthesized and characterized for applications in CO2 photoreduction with H2O. Ce-doped TiO2 were synthesized using sol-gel method and SBA-15 was then added to the sol to prepare Ce-doped TiO2 on SBA-15 nanocomposites. Modification of TiO2 with Ce significantly stabilized the TiO2 anatase phase and increased the specific surface area, which contributed to an improvement of CO production from CO2 reduction. Dispersing Ce-TiO2 nanoparticles on the mesoporous SBA-15 support further enhanced both CO and CH4 production. The superior catalytic activity may be related to the partially embedded Ce-TiO2 nanoparticles in the ordered 1-D pores in SBA-15 that form synergies between the different components of the catalysts and enhance the diffusion and adsorption of CO2. Ag/TiO2 nanocomposites were synthesized by spray pyrolysis technique. This work has demonstrated the feasibility of syngas (H2 and CO) production from a gas mixture of CO2, H2O and CH3OH hrough a photocatalytic reduction process on Ag/TiO2 nanocomposite catalysts under solar irradiation.The material property analysis and photocatalytic activity results showed that the ultrasonic spray pyrolysis method is much superior to conventional wet impregnation process with the advantages of smaller Ag nanoparticles, a better Ag dispersion on TiO2, and a higher fraction of metallic Ag species, which facilitate charge transfer and improve photocatalytic activity. TiO2-MgAl LDOs were synthesized by hydrothermal and coprecipitation method. As the MgAl LDOs concentration increases, TiO2 crystal size was increased. MgAl LDOs grafting on TiO2 cuboids may help improve the adsorption ability of CO2 onto TiO2 which improves the photocatalytic activity of CO2 reduction. Our work also entails the synthesis and characterization of carbon coated TiO2 for the application of Li-ion batteries and sulfur infiltrated porous microsphere carbon (PMC/S) for the application of Li-S batteries. Carbon decorated on commercial TiO2 nanoparticles (P25 and P90) composites with optimized carbon concentration and structure were fabricated by a facile process employing carbonization method. The electrochemical performance of C-P90 was superior to C-P25 because of its higher specific surface area and larger anatase fraction that can accommodate more lithium ions. 1.9% carbon was found to form an optimized carbon layer on TiO2 that can improve the electronic conductivity. The PMC was synthesized by spray pyrolysis method. Then PMC/S was fabricated via a liquid phase infiltration. The novel-structured porous carbon microspheres possess a controllable multi-modal pore size distribution, i.e., a combination of interconnected micropores, mesopores and macropores, which is beneficial for Li-S batteries electrochemical performance. Future work includes further improvement of PMC/S composites to inhibit shuttle effect and improve the electrode performance including the cyclability and rate capability

REVIEW : Synthesis of nanoparticles and nanocomposite of WO3

Tungsten oxide (WO3) is a semiconductor that can be used in a wide variety of applications such as semiconductor gas devices, electronic devices, and photocatalysts. WO3 can be proposed as a substitute for TiO2 because it has a narrow bandgap property, which makes this material active in the UV-Vis spectrum. The purpose of writing this paper is to conduct a literature review on the synthesis of WO3 nanoparticles and nanocomposites using a review method on 50 literature from 2000 to 2020 by reviewing several methods such as hydrothermal methods, sol-gel, low-temperature hydrolysis and, water-in-oil microemulsion in sucrose esters, calcination, flame-assisted spray pyrolysis, ultrasonic, and microwave irradiation. Besides, it is also reviewed based on several starting materials such as sodium tungsten dihydrate, AMT (ammonium metatungsten), ammonium tungstate hydrate, H2WO4, phosphotungsten acid, Cl6W, and W powder

Evolution of Carbon Nanotubes, Their Methods, And Application as Reinforcements in Polymer Nanocomposites: A Review

The demand for increased performance in structural materials has drawn attention to the use of fiber materials as a means of reinforcement to provide structural integrity. Carbon nanotube (CNT) reinforced polymer nanocomposites have become the go-to materials due to their superior properties. CNTs possess a strength 10-100 times higher than steel yet are lighter in weight. Additionally, CNTs have a remarkable thermal stability of up to 2800°C in a vacuum, and an electrical conductivity of 103 S/cm. It also has an electric-current-carrying capacity 1000 times higher than other materials and a thermal conductivity of around 1900 W m-1 K-1, which is almost double that of diamond. This article explores the potential of Carbon Nanotubes (CNTs) to reinforce structural composite materials, improve sensing, and enhance responsiveness. It also examines its structure and classification as single and multi-walled, its synthesis, including laser ablation methods, arc discharge methods, chemical vapor deposition methods, and spray pyrolysis. Additionally, it discusses the applications, structural benefits, and challenges of composite materials

Thermal characterization of plain and carbon nanotube reinforced syntactic foams

Syntactic foams are composite materials in which the matrix phase is reinforced with hollow particles called microballoons. They possess properties such as low moisture absorption, low thermal conductivity and high damage tolerance because of their compositions. Traditionally, syntactic foams are used for many high strength applications and as insulating materials. But for applications demanding better heat dissipation from syntactic foam, conductive filler materials need to be added while maintaining its property of low density. Carbon nanotubes although extremely conductive, have issues of agglomeration in the matrix. In this research, a new approach to the problem of dispersion of nanotubes was attempted by growing the nanotubes on the surface of glass microballoons. S22 glass microballoons with low density were used in this work. Chemical vapor deposition was used for growing nanotubes on the microballoons using nickel as a catalyst. Nickel coating on microballoons was obtained via an electroless plating process. Observations were made on the nickel coating and nanotube growth processes with the help of a Scanning Electron Microscope (SEM). Thickness of the catalyst layer, growth temperature, gas flow rates and the quality of palladium activation were found to be the determining steps for nanotube growth. Transmission Electron Microscopy (TEM) was used to characterize the growth of nanostructures. Multi-walled carbon nanotubes of 6 – 20 nm were grown in this research. The thermal conductivity of nanotube-grown syntactic foam was tested on a Flashline thermal analyzer utilizing a flash method. For comparison purposes, plain and nanotube-mixed syntactic foams were fabricated and tested for conductivity. The effect of amount of nanotube and microballoon on the conductivity of the material was studied. The conductivity increments were low due to thermal boundary resistance occurring at the interface of nanotubes and resin. Nanotube-grown foams increase the thermal conductivity of plain syntactic foam by 86%, as opposed to nanotube-mixed ones which showed lower conductivity values than plain syntactic foam. TEM images showed that the mixing method had nanotubes being highly agglomerated whereas the growing method was successful in creating a well dispersed network of nanotubes

Synthesis of modified zinc oxide nanoparticles using pneumatic spray pyrolysis for solar cell application

In this work, the pneumatic spray pyrolysis was used to synthesize un-doped and carbon doped zinc oxide (ZnO) nanoparticles. The zinc acetate, tetrabutylammonium bromide and ethanol were used as starting materials for the desired ZnO nanoparticles and the prepared samples were annealed at 400 oC in the furnace. The as synthesized un-doped and carbon doped ZnO NPs were evaluated using X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive x-ray spectroscopy (EDX), High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and Ultraviolet-visible spectroscopy (UV-Vis). XRD analysis of the synthesized NPs revealed peaks at 31.90°, 34.50°, 36.34°, 47.73°, 56.88°, 63.04°, 68.20°, and 77.33° belonging to the hexagonal Wurtzite ZnO crystal structure. The incorporation of C species into ZnO lattice was cross examined by monitoring the peak positions of the (100), (002) and (001) planes. These three main peaks of C-ZnO NPs show a peak shift to higher 2θ values which indicates substitutional carbon doping in ZnO NPs. SEM analysis has revealed that the as synthesized NPs have spherical shape and the morphology of the NPs change as the concentration of carbon increases. The EDX spectra of both un-doped and doped ZnO nanoparticles have revealed prominent peaks at 0.51 keV, 1.01 keV, 1.49 keV, 8.87 keV and 9.86 keV. Peaks at, X-ray energies of 0.51 keV and 1.01 keV respectively represent the emissions from the K-shell of oxygen and L-shell of zinc. The L-shell emission at 1.01 keV is considered as convolution of Zn 2p3/2 and Zn 2p1/2 photoelectron energies. The occurrence of these peaks in the EDX endorses the existence of Zn and O atoms in the PSP prepared samples. HRTEM analysis has revealed NPs size modal range from 6.65-14.21 nm for the PSP synthesized samples which is in mutual agreement with the XRD data calculated values. More over the selected area diffraction images displaying the fact that only the diffraction planes of (101), (002) and (100) are responsible for the diffraction pattern belonging to Wurtzite ZnO. RS analysis has revealed that the un-doped ZnO and doped ZnO samples have characteristic Raman vibration modes at 325 cm-1, and 434 cm-1 belonging to Wurtzite ZnO structure. Moreover, the prominent peak at 434 cm-1 which is the characteristic peak of E2(2) (high) mode of the Wurtzite ZnO and the E2(2) (high) has been red shifted by 4 cm-1, as compared to that found in the bulk ZnO. Additionally, the effect of carbon doping through Raman spectroscopy peak shifts of the E2(2) (high) mode, A1(LO) mode and multi-phonon has also been considered and discussed in detail. UV-Vis diffuse reflectance spectroscopy has revealed a red shift of the absorption edge with increase in C doping. Finally, the effect of nano-crystallite size and gradual prominence of C into ZnO lattice due to increase in C doping concentration in the PSP prepared nanoparticles was meticulously elaborated through Raman Spectroscopy analysis