Journal of Science: Advanced Materials and Devices
Abstract The present work reveals the green combustion preparation of the Ag-doped ZnO nanopartic... more Abstract The present work reveals the green combustion preparation of the Ag-doped ZnO nanoparticles (NPs) using turmeric root extract as a fuel. The structure and morphology of Ag-doped ZnO NPs were investigated by several analytical techniques such as XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), FTIR (Fourier Transform Infrared), Raman, XPS (X-Ray Photoelectron Spectroscopy), and UV-Visible Spectroscopy (UV–Vis). From XRD, the crystallite size was found to be about 45 nm which agrees with the TEM results. SEM micrographs reveal the spherical shaped agglomerated particles. XPS measurement anticipates that Ag is mainly in the metallic state and ZnO is in the Wurtzite structure. UV–Visible spectroscopy shows the absorbance peak at 368 nm. Biodiesel synthesis from Terminalia belerica oil with Ag ZnO as a nanocatalyst has been studied. Ag ZnO nanoparticles show hydrogen evolution up to 214 μmolg−1h−1. A convenient synthesis of Nα-protected formamides from protected amino acids was described using Ag ZnO as a catalyst. This method provides good yield of formamides with excellent purity after removal of the catalyst.
Addition of 2D GO to the TiO2 nanowires brings about progressive changes in the optical propertie... more Addition of 2D GO to the TiO2 nanowires brings about progressive changes in the optical properties and photochemical hydrogen production. The composition with progressive addition of GO played a dramatic role in making the material blue shift. The blue shift may happen due to transition from O2− anti-bonding orbital to the Ti4+ lowest empty orbital and also the process of band shifting towards lower wavelength is attributed to quantum confinement effect which occurs due to the transformation of bulk titanate to nanostructure titanate. In this article, we present the results of TiO2 nanowires and its rGO composites. TiO2 with 30 mg rGO nanocomposite exhibits good UV-light induced hydrogen production unlike bare TiO2. Current studies explain how rGO addition can be employed for better hydrogen production.
A CuS–TiO2–Pt showed improved H2 production (746 μmol h−1 g−1) compared to CuS–TiO2 (458 μmol h−1... more A CuS–TiO2–Pt showed improved H2 production (746 μmol h−1 g−1) compared to CuS–TiO2 (458 μmol h−1 g−1) under the irradiation of UV-Vis light which is due to charge separation by the addition of Pt.
Au/TiO2 NPs have been successfully prepared via ionic liquid assisted hydrothermal method and uti... more Au/TiO2 NPs have been successfully prepared via ionic liquid assisted hydrothermal method and utilizing Au/TiO2 NPs for photocatalytic hydrogen production and photochemical and electrochemical reduction of Cr6+ to Cr3+.
Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode ... more Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode materials for sensors and energy storage applications. In this article, we report a facile in situ method for the polymerisation of aniline resulting in the decoration of 1D conducting polyaniline (PANI) nanofibers onto the surface of 2D graphene oxide (GO) nanosheets followed by hydrogel formation at elevated temperature. The synthesized nanomaterial exhibits significant properties for the highly sensitive electrochemical determination as well as removal of environmentally harmful lead (Pb) ions. The square wave anodic stripping voltammetry (SWASV) determination of Pb ions showed good electroanalytical performance with two linear ranges in 0.2-250 nM (correlation coefficient = 0.996) and 250-3500 nM (correlation coefficient = 0.998). The developed protocol has shown a limit of detection (LOD) of about 0.04 nM, which is much lower than that of the World Health Organization (WHO) threshold limits. The prepared electrode showed an average of ∼99.4% removal of Pb ions with a relative standard deviation (RSD) of 3.4%. Selectivity of the electrode towards Pb ions were tested in presence of potential interferences such as Na, K, Ca, Mg, Cu, Cd, Hg, Zn, Co, Ni, Fe and Fe of similar and higher concentrations. The sensor showed good repeatability and reproducibility. The developed protocol was used to analyse samples from industrial effluents and natural water samples. The results obtained were correlated with atomic absorption spectroscopy (AAS).
Effective and low-cost photocatalysts have been synthesized by a simple hydrothermal process. In ... more Effective and low-cost photocatalysts have been synthesized by a simple hydrothermal process. In this process, the two CuO and TiO2 bound one over the other and formed a heterojunction CuO-TiO2 nanocomposite. CuO serves as electron reservoir by receiving electrons from TiO2, which suppresses the recombination of e−/h+ and transfers the received electron to split water, which results in enhanced H2 production. Heterojunction CuO-TiO2 nanocomposite material recorded a maximum of 9284 μmolg−1 H2 production for 2.5 h. The recorded result is 15 times higher than bare TiO2 and 16 times higher than bare CuO. The synthesized materials were characterized and analyzed using various analytical techniques such as XRD, FTIR, UV–vis spectra and the morphology was studied using SEM, TEM, and HRTEM images.
Abstract We report a novel graphene oxide-Cu(II) (GO-Cu 2 + ) composite electrode for electrochem... more Abstract We report a novel graphene oxide-Cu(II) (GO-Cu 2 + ) composite electrode for electrochemical determination of hydrogen peroxide (H 2 O 2 ) in neutral solution (pH = 7.4). Oxygen functional groups such as carboxylic acid, hydroxyl and epoxy present on GO are utilized for the formation of composite with Cu 2 + ions. The synthesized GO-Cu 2 + composite was characterized by X-ray diffraction (XRD) studies and cyclic voltammetry (CV). The surface morphology of the GO and GO-Cu 2 + composite materials was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Elemental analysis was performed using EDS. The prepared electrode showed a good electrocatalytic performance for reduction of H 2 O 2 and mechanistic pathway has been discussed. Amperometric determination for H 2 O 2 was carried out at a applied potential of − 0.25 V vs Ag/AgCl and the result showed a linear response range of 5 μM to 85 μM (correlation coefficient = 0.999) with a detection limit of 0.5 μM (S/N = 3). The sensitivity of the electrode was found to be 0.072 μA μM − 1 and the electrode selectively detected H 2 O 2 in the presence of other potential interferences such as oxygen, glucose, ascorbic acid (AA), dopamine (DA) and uric acid (UA).
We have successfully synthesized ZnO nanoparticles (NPs) from solution combustion method using co... more We have successfully synthesized ZnO nanoparticles (NPs) from solution combustion method using combustible fuel (Green gram). XRD pattern confirms that the prepared compound is composed of wurtzite hexagonal zinc-oxide. FTIR spectrum of ZnO NPs shows the band at ~ 417 cm-1 associated with the characteristic vibration of Zn - O . The UV-Vis spectrum shows a strong absorption band at ~ 365 nm which is blue shifted due to quantum confinement effect. TEM images show the average sizes of the nanoparticles are found to be almost ~ 15–30 nm. The as-synthesized product shows good electrochemical sensing of dopamine. Furthermore the antibacterial properties of ZnO NPs were investigated by their bactericidal activity against four bacterial strains using the agar well diffusion method.
Journal of Science: Advanced Materials and Devices
Abstract The present work reveals the green combustion preparation of the Ag-doped ZnO nanopartic... more Abstract The present work reveals the green combustion preparation of the Ag-doped ZnO nanoparticles (NPs) using turmeric root extract as a fuel. The structure and morphology of Ag-doped ZnO NPs were investigated by several analytical techniques such as XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), FTIR (Fourier Transform Infrared), Raman, XPS (X-Ray Photoelectron Spectroscopy), and UV-Visible Spectroscopy (UV–Vis). From XRD, the crystallite size was found to be about 45 nm which agrees with the TEM results. SEM micrographs reveal the spherical shaped agglomerated particles. XPS measurement anticipates that Ag is mainly in the metallic state and ZnO is in the Wurtzite structure. UV–Visible spectroscopy shows the absorbance peak at 368 nm. Biodiesel synthesis from Terminalia belerica oil with Ag ZnO as a nanocatalyst has been studied. Ag ZnO nanoparticles show hydrogen evolution up to 214 μmolg−1h−1. A convenient synthesis of Nα-protected formamides from protected amino acids was described using Ag ZnO as a catalyst. This method provides good yield of formamides with excellent purity after removal of the catalyst.
Addition of 2D GO to the TiO2 nanowires brings about progressive changes in the optical propertie... more Addition of 2D GO to the TiO2 nanowires brings about progressive changes in the optical properties and photochemical hydrogen production. The composition with progressive addition of GO played a dramatic role in making the material blue shift. The blue shift may happen due to transition from O2− anti-bonding orbital to the Ti4+ lowest empty orbital and also the process of band shifting towards lower wavelength is attributed to quantum confinement effect which occurs due to the transformation of bulk titanate to nanostructure titanate. In this article, we present the results of TiO2 nanowires and its rGO composites. TiO2 with 30 mg rGO nanocomposite exhibits good UV-light induced hydrogen production unlike bare TiO2. Current studies explain how rGO addition can be employed for better hydrogen production.
A CuS–TiO2–Pt showed improved H2 production (746 μmol h−1 g−1) compared to CuS–TiO2 (458 μmol h−1... more A CuS–TiO2–Pt showed improved H2 production (746 μmol h−1 g−1) compared to CuS–TiO2 (458 μmol h−1 g−1) under the irradiation of UV-Vis light which is due to charge separation by the addition of Pt.
Au/TiO2 NPs have been successfully prepared via ionic liquid assisted hydrothermal method and uti... more Au/TiO2 NPs have been successfully prepared via ionic liquid assisted hydrothermal method and utilizing Au/TiO2 NPs for photocatalytic hydrogen production and photochemical and electrochemical reduction of Cr6+ to Cr3+.
Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode ... more Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode materials for sensors and energy storage applications. In this article, we report a facile in situ method for the polymerisation of aniline resulting in the decoration of 1D conducting polyaniline (PANI) nanofibers onto the surface of 2D graphene oxide (GO) nanosheets followed by hydrogel formation at elevated temperature. The synthesized nanomaterial exhibits significant properties for the highly sensitive electrochemical determination as well as removal of environmentally harmful lead (Pb) ions. The square wave anodic stripping voltammetry (SWASV) determination of Pb ions showed good electroanalytical performance with two linear ranges in 0.2-250 nM (correlation coefficient = 0.996) and 250-3500 nM (correlation coefficient = 0.998). The developed protocol has shown a limit of detection (LOD) of about 0.04 nM, which is much lower than that of the World Health Organization (WHO) threshold limits. The prepared electrode showed an average of ∼99.4% removal of Pb ions with a relative standard deviation (RSD) of 3.4%. Selectivity of the electrode towards Pb ions were tested in presence of potential interferences such as Na, K, Ca, Mg, Cu, Cd, Hg, Zn, Co, Ni, Fe and Fe of similar and higher concentrations. The sensor showed good repeatability and reproducibility. The developed protocol was used to analyse samples from industrial effluents and natural water samples. The results obtained were correlated with atomic absorption spectroscopy (AAS).
Effective and low-cost photocatalysts have been synthesized by a simple hydrothermal process. In ... more Effective and low-cost photocatalysts have been synthesized by a simple hydrothermal process. In this process, the two CuO and TiO2 bound one over the other and formed a heterojunction CuO-TiO2 nanocomposite. CuO serves as electron reservoir by receiving electrons from TiO2, which suppresses the recombination of e−/h+ and transfers the received electron to split water, which results in enhanced H2 production. Heterojunction CuO-TiO2 nanocomposite material recorded a maximum of 9284 μmolg−1 H2 production for 2.5 h. The recorded result is 15 times higher than bare TiO2 and 16 times higher than bare CuO. The synthesized materials were characterized and analyzed using various analytical techniques such as XRD, FTIR, UV–vis spectra and the morphology was studied using SEM, TEM, and HRTEM images.
Abstract We report a novel graphene oxide-Cu(II) (GO-Cu 2 + ) composite electrode for electrochem... more Abstract We report a novel graphene oxide-Cu(II) (GO-Cu 2 + ) composite electrode for electrochemical determination of hydrogen peroxide (H 2 O 2 ) in neutral solution (pH = 7.4). Oxygen functional groups such as carboxylic acid, hydroxyl and epoxy present on GO are utilized for the formation of composite with Cu 2 + ions. The synthesized GO-Cu 2 + composite was characterized by X-ray diffraction (XRD) studies and cyclic voltammetry (CV). The surface morphology of the GO and GO-Cu 2 + composite materials was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Elemental analysis was performed using EDS. The prepared electrode showed a good electrocatalytic performance for reduction of H 2 O 2 and mechanistic pathway has been discussed. Amperometric determination for H 2 O 2 was carried out at a applied potential of − 0.25 V vs Ag/AgCl and the result showed a linear response range of 5 μM to 85 μM (correlation coefficient = 0.999) with a detection limit of 0.5 μM (S/N = 3). The sensitivity of the electrode was found to be 0.072 μA μM − 1 and the electrode selectively detected H 2 O 2 in the presence of other potential interferences such as oxygen, glucose, ascorbic acid (AA), dopamine (DA) and uric acid (UA).
We have successfully synthesized ZnO nanoparticles (NPs) from solution combustion method using co... more We have successfully synthesized ZnO nanoparticles (NPs) from solution combustion method using combustible fuel (Green gram). XRD pattern confirms that the prepared compound is composed of wurtzite hexagonal zinc-oxide. FTIR spectrum of ZnO NPs shows the band at ~ 417 cm-1 associated with the characteristic vibration of Zn - O . The UV-Vis spectrum shows a strong absorption band at ~ 365 nm which is blue shifted due to quantum confinement effect. TEM images show the average sizes of the nanoparticles are found to be almost ~ 15–30 nm. The as-synthesized product shows good electrochemical sensing of dopamine. Furthermore the antibacterial properties of ZnO NPs were investigated by their bactericidal activity against four bacterial strains using the agar well diffusion method.
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Papers by T. Ramakrishnappa