Iranian Journal of Materials Science and Engineering

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Indium tin oxide (ITO) nanoparticles were synthesized by green combustion method using indium (In) and tin (Sn) as precursors, and Carica papaya seed extract as novel fuel. This paper highlights effect of tin concentration (5%, 10% and 50%) on microstructural, optical and electrical properties of ITO nanoparticles (NPs). The indium nitrate and tin nitrate solution along with the fuel were heated at 600 °C for 1 h in muffle furnace and obtained powder was calcinated at 650 °C for 3 h to produce ITO NPs. The above properties were investigated using XRD, FTIR, UV-Vis spectroscopy, SEM, TEM and computer controlled impedance analyser. The XRD, SEM and TEM investigations reveals the synthesized NPs were spherical in shape with an increase in average grain size (17.66 to 35 nm) as Sn concentration increases. FTIR investigations confirms the In-O bonding. The optical properties results revealed that the ITO NPs band gap decreased from 3.21 to 2.98 eV with increase in Sn concentration. The ac conductivity of ITO NPs was found to increase with increase in Sn concentration. These synthesised ITO NPs showed the excellent properties for emerging sensor and optical device application.

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Green synthesis refers to the synthesis of nanoparticles using plants and microorganisms. It is preferred over conventional methods as its sustainable, eco-friendly, cost effective and rapid method. The phytochemicals and enzymes present in plants and microorganisms respectively acts as the reducing and capping agent for the synthesis of nanoparticles. Phytochemicals and enzymes have the ability to reduce precursor metal ions into nanoparticles. As the conventional methods involve the use of high energy and toxic chemicals which are harmful to both environment and organisms, these synthesis methods are discouraged. Of the nanoparticles, gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have gained lots of attention owing to their multiple applications and less toxicity. In addition, various in-vitro studies have reported the antimicrobial activity of AgNPs and AuNPs against various microbes. This particular review portrays the methods of nanoparticles synthesis, components of green synthesis, mechanism of green synthesis, antimicrobial activity, other applications and various factors affecting the green synthesis of AgNPs and AuNPs.

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Perovskite materials are widely studied for their super-conducting, magnetic, catalytic and electro-optic properties. Among them, barium stannate (BaSnO₃), finds applications in dielectric and optically active devices, thermally stable capacitors, humidity and gas sensors. In this study, BaSnO₃ was synthesized by chemical and greener methods and comparative analyses has been performed on their electrochemical, third order nonlinear, dye deactivation and bacterial suppression properties. Decreased crystallite size was realized for the green synthesized BaSnO₃. Energy band gaps were 3.23 and 3.04 eV for BaSnO₃ synthesized by normal and greener approach, respectively. The extract mediated sample exhibited increased specific capacitance value. Photocatalytic degradation efficiencies were 78.4% and 89.7%, respectively for BaSnO₃ synthesized by normal and greener approach against methyl violet after 90 min of UV light irradiation. Enhanced nonlinear optical parameters were obtained for the extract mediated BaSnO₃. Excellent antibacterial efficacy against Proteus vulgaris bacteria was realized for the greener BaSnO₃ NPs thanks to the domination of phytochemicals of M. olifera leaf extract.
 

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Researchers are increasingly focusing on green synthesis methods for silver nanoparticles due to their cost-effectiveness and reduced environmental impact. In this study, we utilized an edible bird's nest (EBN), a valuable economic resource, as the primary material for synthesizing silver nanoparticles using only water as the solvent. Metabolite profiling of the EBN extract was conducted using LC-QTOF-MS in positive mode (ESI+), revealing the presence of lipids, glycosides, peptides, polysaccharides, and disaccharides. Upon the addition of silver nitrate to the aqueous EBN extract, noticeable color changes from transparent to brown indicated the successful formation of AgNPs. Subsequent characterization of these silver nanoparticles involved UV-Visible spectroscopy, which revealed an absorption peak at 421 nm. Further characterization was carried out using FESEM, ATR-FTIR spectroscopy, and EDX analysis. The involvement of phenolic agents, proteins, and amino acids in reducing the silver particles was confirmed. The synthesized nanoparticles exhibited a spherical shape, and a particle size ranging from 10 to 20 nm. The presence of elemental silver was confirmed by a strong, intense peak around 3 keV in the EDX spectrum. To assess their potential, the antibacterial properties of the silver nanoparticles against Escherichia coli and Staphylococcus aureus were evaluated using the agar diffusion method.