Carbothermal shock synthesis of high-entropy-alloy nanoparticles

Uniform, Scalable, High-Temperature Microwave Shock for Nanoparticle Synthesis through Defect Engineering

The field of nanotechnology has created great interest among researchers due to its remarkable outcomes in different fields of optoelectronics, medical, pharmaceuticals, chemical, and agricultural importance. It is an emerging cutting-edge technology involving different methodologies for the synthesis of nanoparticles of particular size and shapes. Development of experimental protocols for synthesis of metal nanoparticles of specific size and shape is a necessary advancement of nanotechnology. Although physical and chemical methods have been successfully used to synthesize metal nanoparticles, there is a persistent necessity to develop eco-friendly and sustainable techniques for the synthesis of nanoparticles. Biosynthesis of nanoparticles using a number of fungi, bacteria, actinomycetes, lichen, and viruses have been reported till date but the plant system has emerged as an efficient system due to its distinctive characters like easy availability, low cost, green approach, simpler downstream processing, etc. In the plant system, biosynthesis process is more useful if nanoparticles are produced extracellularly using plants or their extracts and in a controlled approach related to their size, dispersity, and shape. Plant system can also be suitably scaled up for large-scale synthesis of nanoparticles. However, some aspects like role of different biomolecules in synthesis of nanoparticles, understanding the biological mechanism of synthesis process needs to be considered elaborately. In this chapter, we have discussed briefly about plants as a prominent tool for the synthesis of metal nanoparticles. Moreover, different methods of synthesis of nanoparticles, different mechanisms involved in the synthesis process, and also the potential applications of metal nanoparticles have also been discussed.

One of the most important criteria of nanotechnology is the development of clean, nontoxic, and environmentally acceptable ''green chemistry'' procedures, involving organisms ranging from bacteria to fungi. The interactions between microbes and metals have been well documented and the ability of microorganisms to extract and accumulate metals is already employed in biotechnological processes such as bioleaching and bioremediation. The synthesis of chemical, photoelectrochemical, and electronic properties enables the synthesis of nanoparticles of different chemical compositions, well-defined sizes, and distinct morphologies. It is well known that many organisms can synthesize inorganic materials either intra- or extracellularly. The biological synthesis of nanoparticles is easy, efficient, and eco-friendly in comparison to chemical or physical synthesis. Physical and chemical synthesis procedures involve toxic solvents as well as high pressure, energy, and temperature, so in biological synthesis the best option is the synthesis of nanoparticles using microbes. The use of fungi in the synthesis of nanoparticles is a relatively recent addition to the list of microorganisms possessing nanoparticle biosynthesis "ability". The application of fungi to produce nanoparticles is potentially exciting because of their ability to secrete large amounts of enzymes. In comparison with other microbial syntheses, the fungal synthesis of silver nanoparticles (AgNPs) is very easy to handle at laboratory scale and fungi do contain larger proteins in their cell walls. Moreover, it is easy to harvest the mycelia. Nanomedicine is a burgeoning field of research with tremendous prospects for the improvement of the diagnosis and treatment of human diseases. Research is carried out in manipulating microorganisms at the genomic and proteomic levels. With the recent progress and the ongoing efforts in improving particle synthesis efficiency and exploring their biomedical applications, we are hopeful that the implementation of these approaches on a large scale and their commercial applications in medicine and healthcare will take place in the coming years.

The study of nanoparticles is currently an area of intense scientific interest due to a wide range of application possibilities in medical and biological fields. Therefore, national initiatives in the field of nanotechnology and nanoparticle research receive broad government support in many countries of the world. Nanoparticle synthesis methods are simple and can be carried out without special laboratory equipment. The very fact of the simplicity of the synthesis process from the technical side makes the synthesis and use of nanoparticles in medicine, biotechnology and other fields of human activity extremely attractive. Silver nanoparticles have a pronounced antibacterial effect against a wide range of bacterial pathogens. The antioxidant properties of cerium nanoparticles are described, which provide the prospect of their use in the therapy of tumor and viral diseases. That is why the purpose of the work is to analyze and compare possible methods of synthesis of silver and cerium nanoparticles and to single out the most promising method. The analysis of the known methods of synthesis of silver and cerium nanoparticles, as well as a comparison of their advantages and disadvantages, allowed us to conclude that the biological synthesis of nanoparticles is the most promising, in particular with the use of plant extracts. An important feature of the biological method of synthesis of nanoparticles is the absence of toxic reducing agents and the complex multi-stage process in comparison with the chemical method of synthesis. Moreover, the biological method of synthesis allows obtaining nanoparticles of a certain size and shape in a wide range of values, while the physical method is very limited. Regulation of the size and shape of nanoparticles obtained by biological synthesis is provided by a simple change of the synthesis conditions, namely the pH value, acidity, concentration of the corresponding metal salt, etc. Green synthesis is a safe ecological and cost-effective method of synthesis of silver and cerium nanoparticles.

Within the last two decades, the synthesis and application of nanoparticles has evolved as one of the most active fields of research and development, promising solutions to some of humanity’s most pressing needs in cases as diverse as cancer therapy, water purification, or energy storage (Duget et al., 2006; Bazito & Torresi, 2006; Centi & Perathoner, 2009; Feldmann & Goesmann, 2010; Goyal et al., 2011; Kim & van der Bruggen, 2010; Li et al., 2008; Moghimi et al., 2005; Prandeep & Anshup, 2009; Sanvicens & Pilar, 2008; Sides et al., 2002; Theron et al., 2007). Today, nanoparticles are predominantly being applied as particulate materials with enhanced properties as compared to the standard bulk material. One however envisions nanotechnology already in the near future to strongly increase in complexity, leading to the development of hierarchical nanosystems being capable of computing and robotic or even self-replicating tasks (Mallouk & Sen, 2009; Rasmussen et al., 2003; Requicha, 2003; Sanchez & Pumera, 2009). Most future applications are expected to be eventually realised via the so-called bottom-up approach, emanating from nanoparticles as tiny building blocks that self-assemble in a controlled and organised manner to a higher level of hierarchy (Shenhar & Rotello, 2003; Dong et al., 2007). The primary prerequisite for the realisation of this strategy is the availability of high-quality nanoparticles that can act as such building blocks, possessing a predefined and uniform size and shape. Consequently, research on the controlled preparation of nanoparticles has greatly intensified within the last two decades, mainly focusing on carbon-based nanostructures (Mostofizadeh et al., 2011), metals (Cushing et al., 2004; Guo & Wang, 2011), metal oxides (Cushing et al., 2004; Chen & Mao, 2007; Pinna & Niederberger, 2008), semiconductor nanostructures (Trindade et al., 2001) and organic or hybrid nanostructures (Biswas & Ray, 2001; Ballauff, 2003). Remarkable progress has been made in the synthesis of nanoparticles with defined and even complex shape for certain materials (Jun et al., 2006), although a general unterstanding of the formation processes of nanostructured materials appears to remain a long way off.

Green synthesis of metal nanoparticles is a very promising area of research. Silver nanoparticles are the most interesting type of nanoparticle in nanotechnology because they have varied properties, such as antibacterial, antioxidant, and antibiofilm forming properties. This review aims to establish which of the most common approaches for the biological synthesis of nanoparticles is the best. In this work, the methods of synthesis of silver nanoparticles using plant extracts, bacteria, and yeast are considered. Each of these methods has its advantages and disadvantages. The most common method of synthesis of silver nanoparticles is the method using plant extracts, however, stabilizing substances from plant extracts have their own direct biological activity, which can be both enhanced and suppressed by silver nanoparticles. Green synthesis of nanoparticles thanks to microorganisms makes it possible to use a wide range of bacterial strains, but it is important to remember of the pathogenicity of the strains and their danger to humans. From this perspective, the use of yeast for the synthesis of silver nanoparticles is the most promising method, as it allows obtaining a large amount of nanomaterial. The synthesis, thanks to yeast method, allows us to control the size and shape of the nanoparticles. Nanoparticles obtained from yeast lysates have effective antibacterial and antifilm-forming activity.

Nanotechnology is getting an incredible drive due to the potential of manipulating metals into their nano size particles. The synthesis and characterization of nano particles using green technology have many applications. The wet chemical techniques used presently in the synthesis of nano particles are deleterious along with flammable conditions. Silver nanoparticles have the capability of killing microbes in an effective manner. This paper explains about the green technology and pollution free methodology for synthesizing silver particles at nano scale using 1mM silver nitrate solution from the extracts of Carica papaya, Emblica officianalis, Azadirachta indica and Cocos nucifera. When the silver nanoparticles are synthesized the solution turns to brownish yellow colour. The tools used in the characterisation of silver nano particles are Ultra Violet - Visible absorption Spectroscopy and Field Emission Scanning Electron Microscopy. The solutions with silver nanoparticles showed the maximum absorption at 450 nm with Ultra Violet - Visible spectroscopy. It is found that C. Papaya and E. oficianalis showed the maximum absorbance of 0.578 and 0.59 respectively at 450 nm. The average range of the produced silver nano particles are analysed to be 5 – 70 nm with FESEM and the shape is examined to be spherical.

Our modern and technological society requests enhanced energy storage devices to tackle the current necessities. In addition, wearable electronic devices are being demanding because they offer many facilities to the person wearing it. In this manuscript, a historical review is made about the available energy storage devices focusing on super-capacitors and lithium-ion batteries, since they currently are the most present in the industry, and the possible polymeric materials suitable on wearable energy storage devices. Polymers are a suitable option because they not only possess remarkable mechanical resistance, flexibility, long life-times, easy manufacturing techniques and low cost in addition to they can be environmentally friendly, nontoxic, and even biodegradable too. Moreover, the electrical and electrochemical polymer properties can be tunning with suitable fillers giving to versatile conducting polymer composites with a good cost and properties' ratio. Although the advances are promising, there are still many drawbacks that need to be overcome. Future research should focus on improving both the performance of materials and their processability on an industrial scale, where additive manufacturing offers many possibilities. The sustainability of new energy storage devices should not

Facile synthesis of surfactant-free SiO2 nanoparticles via emulsion method

Biochar (BC)-supported graphene-encapsulated zero-valent iron nanoparticle composites (BC-G@Fe0) are promising engineering nanocomposites that can be used to scavenge heavy metal from wastewater. However, the production of BC-G@Fe0 through carbothermal reduction using biomass as a carbon source remains challenging because of biomass pyrolysis complications. Here, we examined two carbothermal reduction routes for preparing BC-G@Fe0 using bamboo as the carbon source. The first route impregnated Fe ions (Fe2+/3+) into unpyrolyzed bamboo particles initially, followed by carbonization at 600–1000 °C. This process produced BC-G@Fe0 dominated by iron carbide (Fe3C), which led to low heavy metal removal efficiency (i.e., Cu2+ capacity of < 0.3 mmol g−1). In the second route, bamboo particles were pyrolyzed (600 °C) to biochar first, followed by impregnating this biochar with Fe ions, and then carbonized at 600–1000 °C. This route produces zero-valent iron nanoparticles, which resulted in high heavy metal removal capacities (i.e., 0.30, 1.58, and 1.91 mmol g−1 for Pb2+, Cu2+, and Ag+, respectively). The effects of carbonization temperature (600–1000 °C), iron source (i.e., iron nitrates, iron sulfate, ferrous chloride, and ferric chloride), and iron loading (5–40%) on the morphology, structure, and heavy metal ion aqueous uptake performance of BC-G@Fe0 were also investigated. This study revealed the formation mechanisms of BC-G@Fe0 through biomass carbothermal reduction, which could guide the application-oriented design of multifunctional iron-BC composites for water remediation.Graphical

Synthesis of high purity rutile nanoparticles from medium-grade Egyptian natural ilmenite

This paper reports the green synthesis of Ag, Cu and AgCu nanoparticles at room temperature using palm leaves extract. The purpose of this study is to eliminate the use of chemicals in the synthesis of nanoparticles and evaluate the efficiency of the palm leaves extract as the reducing and stabilizing agents. The palm leaves extract was added to metal salt solution and continuously stirred until reaction completed. The produced nanoparticles were analyzed using atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The analyses revealed that palm leaves extract has efficiently reduced the silver ions, but not the copper ions. During synthesis of AgCu nanoparticles, simultaneous reduction was occurred leading to formation of alloyed nanoparticles. Biomolecules from the palm leaves extract adsorbed on the surface of nanoparticles forming a capping layer thus stabilized the nanoparticles. The produced Ag and Cu nanoparticles were predominantly spherical with the particle size of Cu nanoparticles were larger than Ag nanoparticles. The AgCu nanoparticles closely resembled the Ag nanoparticles due to high Ag content with average size of 13nm. Therefore, palm leaves extract has a potential to be a good reducing and stabilizing agents.

In recent years, there has been an increasing interest in the development of plant‐based nanoparticles due to their numerous benefits over conventional physio‐chemical methods, including sustainability and environmental safety. Green synthesis, a process that produces safe and sustainable goods without the use of harsh chemicals or other harmful processes, is gaining popularity. The current study focuses on the green synthesis of copper oxide nanoparticles using Piper nigrum leaf extracts, their characterization, and applications. The synthesis of nanoparticles was confirmed by changes in colour, further endorsed by UV–visible spectroscopy. Copper oxide (CuO) nanoparticles were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). CuO nanoparticle sizes ranged between 58.23 and 69.89 nm and were spherical in shape. FTIR results indicated a functional group capped on the nanoparticle surface. The antibacterial activity of the copper oxide nanoparticles was tested, and they exhibited the significant decrease in bacterial concentration and the largest zone of inhibition, making them an efficient disinfectant. Antimicrobial activity against Bacillus subtilis and Escherichia coli was observed. Furthermore, the synthesized CuO nanoparticles exhibited a high affinity for safranin dyes and demonstrated maximum removal efficiency. This makes them an effective agent for removing dyes in wastewater from industries such as clothing manufacturing. Safranin dye was successfully removed with an efficiency of 78% using nanoparticles. In conclusion, the green synthesis of copper oxide nanoparticles using plant extracts presents an eco‐friendly and sustainable approach for producing nanoparticles with a wide range of potential applications.

Controllable synthesis and structure analysis of VCxO1-x solid solution by experiment and first-principles calculation

In biomedical, toxicological, and optoelectronic applications, the size of nanoparticles is one of the decisive factors. Therefore, synthesis of nanoparticles with controlled sizes is required. The current methods for synthesis of larger gold nanoparticles (GNPs, ~200 nm) are complex and tedious, producing nanoparticles with a lower yield and more irregular shapes. Using ferrocene as a primary reducing agent and stabilizer, sodium citrate as a dispersant, and sodium borohydride as an accessory reducing agent, GNPs of 200 nm were synthesized in a one pot reaction. Besides the roles of reducing agent and GNP stabilizer, ferrocene also served a role of quantitative marker for ligand loading, allowing an accurate determinate of surface ligands.