Investigation on structural, thermal, optical and sensing properties of meta-stable hexagonal MoO3 nanocrystals of one dimensional structure

Hexagonal molybdenum oxide (h-MoO3) was synthesized by a solution based chemical precipitation technique. Analysis by X-ray diffraction (XRD) confirmed that the as-synthesized powder had a metastable hexagonal structure. The characteristic vibrational band of Mo–O was identified from Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images clearly depicted the morphology and size of h-MoO3. The morphology study showed that the product comprises one-dimensional (1D) hexagonal rods. From the electron energy loss spectroscopy (EELS) measurement, the elemental composition was investigated and confirmed from the characteristic peaks of molybdenum and oxygen. Thermogravimetric (TG) analysis on metastable MoO3 revealed that the hexagonal phase was stable up to 430 °C and above this temperature complete transformation into a highly stable orthorhombic phase was achieved. The optical band gap energy was estimated from the Kubelka–Munk (K–M) function and was found to be 2.99 eV. Finally, the ethanol vapor-sensing behavior was investigated and the sensing response was found to vary linearly as a function of ethanol concentration in the parts per million (ppm) range

Surface-Sulfurized Zn-MOF Grown on Ni-Foam with Various Sulfurizing Agents for Aqueous Hybrid Supercapacitor Device Fabrication

Metal–organic frameworks (MOFs) are an emerging material with a high specific surface area, desired morphology, and tunable pore size. However, MOFs suffer due to low electrical conductivity. Transition-metal sulfides are excellent supercapacitor materials because of their large storage capacity and electrical conductivity. To preserve a high surface area and obtain high electrical conductivity, Zn-MOF is directly grown on Ni-foam, and its surface is modified through various sulfurizing agents. The as-fabricated Zn-MOF on Ni-foam exhibits a vertically oriented triangular rod-like morphology. Banana blossom, fiber, and rod-like morphologies are obtained due to the surface etching and surface sulfurization process by sulfurizing agents thioacetamide (TAA), sulfur (S), and thiourea (TU), respectively. The role of iR compensation in cyclic voltammetry analysis with higher mass-loading electrodes is established. The variations in its charge storage mechanism and charge-transfer kinetics corresponding to various sulfurizing agents are examined. Compared to other commonly used sulfurizing agents, TAA-assisted surface-sulfurized Zn-MOF provided excellent charge storage performance. It exhibits a maximum areal capacity of 4484 mC cm–2 (specific capacity of 747.3 C g–1) at a current density of 10 mA cm–2. The as-fabricated aqueous hybrid supercapacitor device exhibits a maximum specific energy of 77.8 W h kg–1 at a specific power of 0.73 kW kg–1, even with a higher mass loading of 12.2 mg. The role and importance of mass loading are described by using an expanded Ragone plot

Surface-Sulfurized Zn-MOF Grown on Ni-Foam with Various Sulfurizing Agents for Aqueous Hybrid Supercapacitor Device Fabrication

Metal–organic frameworks (MOFs) are an emerging material with a high specific surface area, desired morphology, and tunable pore size. However, MOFs suffer due to low electrical conductivity. Transition-metal sulfides are excellent supercapacitor materials because of their large storage capacity and electrical conductivity. To preserve a high surface area and obtain high electrical conductivity, Zn-MOF is directly grown on Ni-foam, and its surface is modified through various sulfurizing agents. The as-fabricated Zn-MOF on Ni-foam exhibits a vertically oriented triangular rod-like morphology. Banana blossom, fiber, and rod-like morphologies are obtained due to the surface etching and surface sulfurization process by sulfurizing agents thioacetamide (TAA), sulfur (S), and thiourea (TU), respectively. The role of iR compensation in cyclic voltammetry analysis with higher mass-loading electrodes is established. The variations in its charge storage mechanism and charge-transfer kinetics corresponding to various sulfurizing agents are examined. Compared to other commonly used sulfurizing agents, TAA-assisted surface-sulfurized Zn-MOF provided excellent charge storage performance. It exhibits a maximum areal capacity of 4484 mC cm–2 (specific capacity of 747.3 C g–1) at a current density of 10 mA cm–2. The as-fabricated aqueous hybrid supercapacitor device exhibits a maximum specific energy of 77.8 W h kg–1 at a specific power of 0.73 kW kg–1, even with a higher mass loading of 12.2 mg. The role and importance of mass loading are described by using an expanded Ragone plot

Fabrication of corrosion resistant, bioactive and antibacterial silver substituted hydroxyapatite/titania composite coating on Cp Ti

The present work is aimed at developing a bioactive, corrosion resistant and anti bacterial nanostructured silver substituted hydroxyapatite/titania (AgHA/TiO(2)) composite coating in a single step on commercially pure titanium (Cp Ti) by plasma electrolytic processing (PEP) technique. For this purpose 2.5 wt% silver substituted hydroxyapatite (AgHA) nanoparticles were prepared by microwave processing technique and were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) methods. The as-synthesized AgHA particles with particle length ranging from 60 to 70 nm and width ranging from 15 to 20 nm were used for the subsequent development of coating on Cp Ti. The PEP treated Cp Ti showed both titania and AgHA in its coating and exhibited an improved corrosion resistance in 7.4 pH simulated body fluid (SBF) and 4.5 pH osteoclast bioresorbable conditions compared to untreated Cp Ti. The in vitro bioactivity test conducted under Kokubo SBF conditions indicated an enhanced apatite forming ability of PEP treated Cp Ti surface compared to that of the untreated Cp Ti. The Kirby-Bauer disc diffusion method or antibiotic sensitivity test conducted with the test organisms of Escherichia coli (E. coli) for 24 h showed a significant zone of inhibition for PEP treated Cp Ti compared to untreated Cp Ti. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Comparative study on the magnetic properties of iron oxide nanoparticles loaded on mesoporous silica and carbon materials with different structure

Here we demonstrate the fabrication of magnetic iron oxide nanoparticles in SBA-15, KIT-6, hexagonally ordered mesoporous carbon (CMK-3), and carbon nanocage (CNC), and compare their unusual magnetic properties. We also demonstrate that pore diameter of the mesoporous silica supports dictates the particle diameter of the iron oxide nanoparticles confined in the porous matrix. The effect of the structure, composition, and the textural parameters of the mesoporous supports on the magnetic properties of the iron oxide nanoparticles has been clearly demonstrated. It has also been found that the interaction between the iron oxide nanoparticles, nature of the mesoporous supports, and the size of the nanoparticles play a critical role in controlling their magnetic properties. Among the mesoporous supports studied, carbon nanocage is found to be superior over CMK-3, SBA-15, and KIT-6 for the fabrication of highly super-paramagnetic iron oxide nanoparticles. Typical saturation magnetization for magnetic nanoparticles confined to CNC, CMK-3, KIT-6, and SBA-15 are 40, 27.18, 11.15, and 10.62 emu/g, respectively. An important finding is that our silica-hybrid magnetic materials exhibit larger values of coercivities than the carbon based supports, which may be due to the difference in the insulation properties of the supports. Coercivities values range from 500 Oe [CNC, carbon-based] to 3500 Oe [SBA-15, silica-based]. It has been also found that the particle–particle interaction is maximum for the magnetic particles confined to CNC