Synthesis and performance of bismuth trioxide nanoparticles for high energy gas generator use

A review on bismuth-based nanocomposites for energy and environmental applications

Bismuth, a heavy metal which is found to be inexpensive and at a reduced cost, is utilized in the synthesis of different nanomaterials with novel structure, remarkable physical and chemical properties, adjustable bandgap, notable efficiency for photothermal conversion. These characteristics have made this element desirable for various applications such as storage and conversion of energy, electronics, sensors, photocatalysis, and other biomedical applications. These review papers are the vital points for the students, this report guides them to the research papers which focus on the impressive development in the area of bismuth and similar nanostructures. The purpose of the present review is to discuss the various synthesis routes of bismuth-based nanomaterials along with green synthesis, different nanostructures of bismuth, their significant properties, diverse applications and directions for the upcoming research. Therefore, with these different tuneable synthesis methods of bismuth-based nanomaterials combined with their novel properties, would elucidate on the future devices based on various nanostructures of bismuth.

Energy Release Characteristics and Reaction Mechanism of PTFE/Al/Bi2O3 Reactive Materials under Drop-Hammer Test

To obtain the influence of the Bi₂O₃ particle content of a PTFE/Al/Bi₂O₃ reactive material (later referred to as PAB) on its shock-induced chemical reaction (SICR) characteristics, five kinds of PAB with different Bi₂O₃ contents were prepared; the reaction process in a drop-hammer test, recorded using a high-speed camera, was analyzed. The ignition and reaction mechanisms of PAB under mechanical impact were analyzed based on the thermochemical reaction characteristics and the microstructure. The results show that with an increase in Bi₂O₃ content, the shock-induced chemical reaction duration and the sensitivity of PAB increase, and then decrease. When the Bi₂O₃ content is 9%, the impact sensitivity is the highest and the reaction duration is the longest. The heating at the crack tip is responsible for PAB ignition under long-pulse low-velocity impact. During ignition, PAB undergoes several physicochemical changes such as the melting of PTFE, a PTFE/Bi₂O₃ reaction, an Al/Bi₂O₃ reaction, pyrolysis of the melted PTFE, and a C₂F₄/Al reaction; moreover, the presence of Bi₂O₃ decreases the excitation threshold of the reactive material, which facilitates the propagation of the reaction and improves the degree of the reaction and overall energy release of the reactive material.

From nanoparticles to on-chip 3D nanothermite: electrospray deposition of reactive Al/CuO@NC onto semiconductor bridge and its application for rapid ignition

Nanothermites composed of nano-fuels and oxidants are attractive energetic materials, which have potential applications in microscale energy-demanding systems. Herein, nano-Al/CuO with nitrocellulose (NC) binder have been bottom-up assembled on semiconductor bridge (SCB) chip by electrospray, from nanoparticles to three-dimensional (3D) deposited structure. The morphological and compositional characterization confirms the constituents in Al/CuO@NC are homogeneously mixed at nano scale and the 3D structure at micro scale is tunable. The as-deposited Al/CuO@NC exhibits excellent energy output and superior chemical reactivity. Specifically, the heat release of Al/CuO@NC (1179.5 J g^-1) is higher than that of random mixed Al/CuO (730.9 J g^-1). Benefiting from outstanding exothermic properties, the material integrated with SCB initiator chip (Al/CuO@NC-SCB) for potential ignition application was investigated. The Al/CuO@NC-SCB micro energetic initiator can be functioned rapidly (with delay time of 2.8 μs) and exhibits superb ignition performances with violent explosion process, high combustion temperature (4636 °C) and successful ignition of B/KNO₃ propellant, in comparison to SCB initiator. The strategy provides promising route to introduce nano reactive particles into various functional energy-demanding systems for potential energetic applications.

Highly Reactive Metastable Intermixed Composites (MICs): Preparation and Characterization

Highly reactive metastable intermixed composites (MICs) have attracted much attention in the past decades. The MIC family of materials mainly includes traditional metal-based nanothermites, novel core-shell-structured, 3D ordered macroporous-structured, and ternary nanocomposites. By applying special fabrication approaches, highly reactive MICs with uniformly dispersed reactants, "layer-by-layer" or "core-shell" structures, can be prepared. Thus, the combustion performance can be greatly improved, and the ignition characteristics and safety can be precisely controlled by using a certain preparation strategy. Here, the preparation and characterization of the MICs that have been developed during the past few decades are summarized. Traditional preparation methods for MICs generally include physical mixing, high-energy ball milling, sol-gel synthesis, and vapor deposition, while the novel methods include self-assembly, electrophoretic deposition, and electrospinning. Various preparation procedures and the ignition and combustion performance of different MIC reactive systems are compared and discussed. In particular, the advantages of novel structured MICs in terms of safety and combustion efficiency are clarified, based on which suggestions regarding the possible future research directions are proposed.

Core/shell CuO/Al nanorod thermite film based on electrochemical anodization

In this study, a new method was reported for the fabrication of the nanostructured CuO/Al thermite film on a Cu substrate. The CuO nanorod (NR) arrays grew vertically from the Cu surfaces by electrochemical anodization processes, followed by the deposition of an Al layer on the CuO NRs via magnetron sputtering to form a core/shell CuO/Al nanothermite film, whose component, structure and morphology were subsequently characterized. In addition, the energy-release characteristics of the obtained nanothermite film were investigated using thermal analyses and laser ignition tests. All evidence demonstrates that the obtained CuO/Al is of a uniform structure and has superb energy performance. Impressively, the resulting material is potentially useful in applications of functional energetic chips due to its easy integration with microelectromechanical systems (MEMS) technologies.

Aluminum nanopowder: A substance to be handled with care

Aluminum nanopowders are increasingly used in various areas of research in materials and physical chemistry. Their unconventional properties are still little understood and make their handling sometimes quite hazardous. In this article, we report the case of apparently benign mixtures of Al with sulfuric acid (H₂SO₄), which violently explode when they are exposed to a flame. The explosions of 100mg samples were observed by high speed video (60000fr/s). These experiments have showed a three-step mechanism, in which the primary hydrogen combustion ignites and disperses the nano-Al/H₂SO₄ paste in clusters with high velocities (∼100m/s). The combustion of the paste increases the hydrogen release and initiates the explosion of the H₂/air mixture, which propagates at high velocities (760-1060m/s). This effect was not observed with micron-sized Al powders, and it is a good illustration of new hazards with nano-Al. Extreme caution is hence recommended to chemists who handle such materials.

Nanothermite with Meringue-like Morphology: From Loose Powder to Ultra-porous Objects

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. Nanothermites are combustible materials made up of inorganic fuel and an oxidizer. In nanothermite foams, aluminum is the fuel and aluminum phosphate and tungsten trioxide are the oxidizing moieties. The highest flame propagation velocities (FPVs) in nanothermites are observed in loose powders and FPVs are strongly decreased by pelletizing nanothermite powders. From a physical standpoint, nanothermite loose powders are metastable systems. Their properties can be altered by unintentional compaction induced by shocks or vibrations or by the segregation of particles over time by settling phenomena, which originates from the density differences of their components. Moving from a powder to an object is the challenge that must be overcome to integrate nanothermites in pyrotechnic systems. Nanothermite objects must have both a high open porosity and good mechanical strength. Nanothermite foams meet both of these criteria, and they are prepared by dispersing a nano-sized aluminothermic mixture (Al/WO3) in orthophosphoric acid. The reaction of aluminum with the acid solution gives the AlPO4 "cement" in which Al and WO3 nanoparticles are embedded. In nanothermite foams, aluminum phosphate plays the dual role of binder and oxidizer. This method can be used with tungsten trioxide, which is not altered by the preparation process. It could probably be extended to some oxides, which are commonly used for the preparation of high performance nanothermites. The WO3-based nanothermite foams described in this article are particularly insensitive to impact and friction, which makes them far safer to handle than loose Al/WO3 powder. The fast combustion of these materials has interesting applications in pyrotechnic igniters. Their use in detonators as primers would require the incorporation of a secondary explosive in their composition.

Thermal behavior of nitrocellulose-based superthermites: effects of nano-Fe2O3 with three morphologies

Superthermites with three Fe₂O₃ morphologies (rod-like, polyhedral, and olivary) were synthesized. The morphological effects of Al/Fe₂O₃ on the thermal decomposition property of nitrocellulose (NC) were investigated.

A novel nano-energetic system based on bismuth hydroxide

We report the first study of gas generation and thermal wave behavior during the performance of a novel nano-energetic system based on aluminum and bismuth hydroxide Al–Bi(OH)₃.

Sulfates-based nanothermites: an expanding horizon for metastable interstitial composites

Metal sulfates (Ba, Bi, Ca, Cu, Mg, Mn, Na, Zn, Zr) were used as oxidizers in reactive compositions with Al nanopowder. These new kinds of nanothermites have outstandingly high reaction heats (4-6 kJ g(-1) ) compared to conventional Al/metal oxides (1.5-4.8 kJ g(-1) ) and also have good combustion velocities (200-840 m s(-1) vs 100-2500 m s(-1) ). These compositions are extremely insensitive to friction making their preparation and handling easy and safe. The sulfate hydration water increases the reaction heats and has a significant effect on the sensitivity to impact and to electrostatic discharge. The reaction of Al with water is easier to initiate than the one with sulfate which leads to two possible decomposition modes for samples exposed to an open flame. The pyrotechnical properties observed with sulfates have also been found for other sulfur oxygenates (SO3 (2-) , S2 O3 (2-) , S2 O8 (2-) ) which opens up new horizons in the domain of metastable interstitial composites.

Combustion characterization and modeling of novel nanoenergetic composites of Co3O4/nAl

Novel Co₃O₄nanobelts based bulk nanoenergetic systems have been developed which are able to generate mild to moderate peak pressure and pressurization rates as demanded in shock wave mediated biomedical applications.

Nanostructured energetic composites: synthesis, ignition/combustion modeling, and applications

Nanotechnology has stimulated revolutionary advances in many scientific and industrial fields, particularly in energetic materials. Powder mixing is the simplest and most traditional method to prepare nanoenergetic composites, and preliminary findings have shown that these composites perform more effectively than their micro- or macro-sized counterparts in terms of energy release, ignition, and combustion. Powder mixing technology represents only the minimum capability of nanotechnology to boost the development of energetic material research, and it has intrinsic limitations, namely, random distribution of fuel and oxidizer particles, inevitable fuel pre-oxidation, and non-intimate contact between reactants. As an alternative, nanostructured energetic composites can be prepared through a delicately designed process. These composites outperform powder-mixed nanocomposites in numerous ways; therefore, we comprehensively discuss the preparation strategies adopted for nanostructured energetic composites and the research achievements thus far in this review. The latest ignition and reaction models are briefly introduced. Finally, the broad promising applications of nanostructured energetic composites are highlighted.

Genotoxic effects of Bismuth (III) oxide nanoparticles by Allium and Comet assay

Genotoxic effects of Bismuth (III) oxide nanoparticles (BONPs) were investigated on the root cells of Allium cepa by Allium and Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at five different concentrations (12.5, 25, 50, 75, and 100ppm) for 4h. Exposure of BONPs significantly increased mitotic index (MI) except 12.5ppm, total chromosomal aberrations (CAs) in Allium test. While stickiness chromosome laggards, disturbed anaphase-telophase and anaphase bridges were observed in anaphase-telophase cells, pro-metaphase and c-metaphase in other cells. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan's multiple range test was performed. These results indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells.