Development of reliable and eco-accommodating methods for the synthesis of nanoparticles is a vital step in the field of nanotechnology. Silver nanoparticles are important because of their exceptional chemical, physical, and biological properties, and hence applications. In the last decade, numerous efforts were made to develop green methods of synthesis to avoid the hazardous byproducts. This review describes the methods of green synthesis for Ag-NPs and their numerous applications. It also describes the comparison of efficient synthesis methods via green routes over physical and chemical methods, which provide strong evidence for the selection of suitable method for the synthesis of Ag-NPs.

Various methods for the synthesis of copper nanoparticles employing chemical, physical and biological techniques considering bottom-up and top-down methods synthesis have been studied. The properties of copper nanoparticles depend largely on their synthesis procedures. The results from various investigations performed by di®erent scientists using these methods have been summarized. The applications, characterization techniques, advantages and disadvantages of each synthesis method are also the point of discussion. A detailed study of the results reveals that chemical reduction methods are most suitable for the synthesis of copper nanoparticles. Chemical reduction of copper salts using ascorbic acid (Vitamin C) is a new and green approach in which ascorbic acid is used both as the reduction and capping agent. This approach is the most e®ective and is also economical. Wide applications have been reported in various¯elds, including heat transfer, catalyst production, electronics and medicine at a commercial scale. This process is nontoxic, environment-friendly and economical. The applications, characterization techniques, advantages and disadvantages of each synthesis method have been presented.

Chemical Reduction technique was employed to prepared highly stable and dispersed Copper nanoparticles using L-Ascorbic Acid (Vitamin C) as reducing as well as capping agent. In this technique, cupric chloride was used as precursor. The effects of different molar ratios of L-Ascorbic Acid on the concentration and size of copper nanoparticles were studied. The Copper nanoparticles were characterized by X-Ray Diffraction, Atomic Absorption Spectrometry, and Fourier Transform Infrared Spectrometry. The results show that with the increase in the molar ratio of L-ascorbic acid the concentration of Copper nanoparticles were also increased. The average particles size of copper nanoparticle was found in the range of 50-60 nm. The product was kept in ambient conditions for three month but no sedimentation or separation was observed. The use of ascorbic acid makes the process a non-toxic, cost effective and environmental friendly green method.

Summary The energy crisis has reached to an alarming situation due to increase in population. To overcome the shortfall of energy, solid oxide fuel cell (SOFC) being cheap, clean, and efficient renewable energy source is getting attention for electricity generation. Out of the three main components as anode, electrolyte, and cathode; anode/fuel electrode is an important component of SOFC because it allows the flow of electrons via external circuit to cathode generating the electric current and hence requires high electrical conductivity. In this review, anode materials synthesized until now are reviewed and by careful analysis categorized on the basis of operating temperature, conductivity, electrode polarization resistance, and structure. This comparison and categorization will provide selection criteria for state‐of‐the‐art and highly efficient anode materials for SOFC. In addition, the synthesis methods have been reviewed on the basis of their pros and cons, which will further facilitate the researchers to select the best synthesis method so as to get optimized properties of materials.

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Nickel ferrite thin films were synthesized by pulsed laser deposition. It was determined that the monotonic increase in saturation magnetization and the non-monotonic increase in electrical conductivity depend on the oxygen partial pressure during the growth of the thin films. A substantial reduction in magnetization was found which ranged between 0.4% and 40% of the bulk value as the oxygen partial pressure increased from 0.2 × 10−6 Torr to 500 mTorr during the deposition of the films. There was a three orders of magnitude increase in conductivity for the sample prepared under the most oxygen deficient environment (partial pressure of oxygen 0.2 × 10−6 Torr). These variations in saturation magnetization and conductivity are described within the framework of cation/oxygen vacancies in an inverse spinel nickel ferrite structure. The changes in the electronic structure due to the presence of the vacancies were investigated using x-ray photoelectron spectroscopy, which confirmed the formation of lower valent Ni for the samples prepared in an oxygen deficient atmosphere.

The ablation of Cd has been performed by employing Q-switched Nd: YAG 10 ns laser pulses with a central wavelength of 1064 nm for a pulsed energy of 200 mJ under various ambient environments of argon, air and helium. The optical emission spectroscopy of Cd plasma has been studied under different filling pressures of shield gases ranging from 5 torr to 760 torr using LIBS spectrometer system. The effect of different gases and their pressures on the intensity of spectral emission, electron temperature and density of the laser-produced plasma has been investigated. SEM analysis has been performed to investigate the dependence of surface morphological changes of an irradiated target on the nature and pressure of an ambient gas. A strong correlation has revealed the vital role of electron temperature and density of laser-induced plasma for the surface modification of Cd. These results strongly indicate that the nature and pressure of the ambient atmosphere is one of the controlling factors of the plasma characteristics, as well as the factors related to the laser energy absorption for surface modification.

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