S. Vadivel

Facile synthesis of novel CaFe2O4/g-C3N4 nanocomposites for degradation of methylene blue under visible-light irradiation.

Hybrid organic/inorganic nanocomposites comprised of calcium ferrite (CaFe2O4) and graphitic carbon nitride (g-C3N4) were prepared via a simple two-step process. The hybridized CaFe2O4/g-C3N4 heterostructure was characterized by a variety of techniques, including X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, electrochemical impedance spectroscopy (EIS), and photoelectrochemical studies. Photocatalytic activity of the prepared samples was evaluated against degradation of methylene blue (MB) under visible-light irradiation. The photocatalytic activity of CaFe2O4 30%/g-C3N4 nanocomposite, as optimum photocatalyst, for degradation of MB was superior to the pure CaFe2O4 and g-C3N4 samples. It was demonstrated that the photogenerated holes and superoxide ion radicals were the two main reactive species towards the photocatalytic degradation of MB over the nanocomposite. Based on the experimental results, a possible photocatalytic mechanism for the MB degradation over the nanocomposite was proposed. This work may provide some inspiration for the fabrication of spinel ferrites with efficient photocatalytic performance.

Fine cutting edge shaped Bi2O3rods/reduced graphene oxide (RGO) composite for supercapacitor and visible-light photocatalytic applications

Bi2O3 rods/RGO composite has been synthesized by a simple precipitation and calcination method. The crystallnity, structural, and morphological features were studied by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM) techniques. The supercapacitor behavior was studied using cyclic voltammetry, galvanostatic charge discharge and impedance analysis, respectively. The Bi2O3 rods/RGO nanocomposite exhibits a maximum specific capacitance of 1041Fg-1 at a current density of 2Ag-1. The photocatalytic activity of Bi2O3 rods/RGO composite was evaluated by photocatalytic degradation of methylene blue (MB) dye under visible-light irradiation. The enhancement of photocatalytic properties of Bi2O3 rods/RGO composite attributed to the synergistic effect between Bi2O3 rods and graphene sheets which effectively prevents recombination of the photogenerated electron-hole pairs in Bi2O3 rods. The present study provides a new approach in improving the performance of Bi2O3 rods/RGO composite in energy and environmental applications.

Constructing novel Ag nanoparticles anchored on MnO2 nanowires as an efficient visible light driven photocatalyst

In this study, novel Ag@MnO2 nanowires were constructed, using a one step hydrothermal method, which exhibited excellent efficiency towards the photodegradation of organic contaminants under visible-light driven irradiation. The resulting Ag@MnO2 nanowires were systematically characterized using various spectroscopic and microscopic techniques. Morphological characterizations show that the Ag nanoparticles are well anchored on the surface of the MnO2 nanowires. The N2 adsorption/desorption studies revealed that the as prepared photocatalyst possesses mesoporosity. The optical properties and energy band gap structures were studied using UV-visible diffuse reflectance spectroscopy. The photocatalytic activity enhancement of the Ag@MnO2 (5%) nanowires could be ascribed to the efficient separation of the photogenerated electron–hole pairs compared to other Ag@MnO2 nanowires and pure MnO2. The possible photocatalytic mechanism was proposed for this enhanced charge separation performance using photoluminescence spectra analysis, electrochemical impedance spectroscopy (EIS) spectra and photocurrent density. Furthermore, photocatalytic mechanism investigations demonstrate that ˙OH and O2˙− play a key role and h+ plays a minor role in the photocatalytic process. We believe that our findings can open a new avenue for the photocatalytic applications of Ag@MnO2 nanowires.

Biomolecule-assisted solvothermal synthesis of Cu2SnS3 flowers/RGO nanocomposites and their visible-light-driven photocatalytic activities

Elimination of organic pollutants from wastewaters under visible-light irradiation is a venerable challenge in the fields of environmental and material science. In this work, we present a facile eco-friendly method to fabricate novel Cu2SnS3 flowers/RGO (Cu2SnS3/RGO) nanocomposites via a solvothermal method using L-cysteine as a sulphur source and linker. The crystal structure, morphology, purity, spectroscopic, and charge carrier separation properties of the synthesized samples were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and X-ray energy-dispersive spectroscopy (EDS), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and electrochemical impedance spectroscopy (EIS). The photocatalytic performance of the Cu2SnS3/RGO nanocomposites was evaluated by photocatalytic decolorization of eosin under visible-light irradiation. Results showed that the Cu2SnS3/RGO (3%) nanocomposite exhibits enhanced photocatalytic activity compared with the pure Cu2SnS3. The improved photocatalytic activity of the nanocomposite was mainly attributed to the formation of well-defined interface between Cu2SnS3 and graphene sheets, which greatly enhance the charge carrier separation efficiency in the Cu2SnS3 semiconductor.

Supercapacitors studies on BiPO4 nanoparticles synthesized via a simple microwave approach

Abstract BiPO4 nanomaterial was synthesized using EDTA (ethylene diamine tetra acetic acid) as the surfactant via a simple microwave method. The structure and morphology of BiPO4 were systematically characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (FE-SEM) studies. The obtained BiPO4 nanoparticles were, on average, 150–300 nm. The electrochemical results showed that the specific capacitance of BiPO4 obtained using the microwave route was up to 104 Fg−1 at a current density of 1 Ag−1 with a large potential window of 1.7 V. The material showed excellent cycling stability (92% capacitance retention) after 500 cycles at a current density of 1 Ag−1.

Preparation and characterization of WO3 bonded imidazolium sulfonic acid chloride as a novel and green ionic liquid catalyst for the synthesis of adipic acid

A novel nano WO3-bonded imidazolium-sulfonic acid chloride (WO3-IL) was prepared, and characterized by FT-IR, XRD, SEM, TEM, EDX and BET. The as synthesized WO3 nanoparticle supported ionic liquid is studied as a heterogeneous catalyst for the liquid phase oxidation of cyclohexene to adipic acid. Apart from cyclohexene, a few other six-eight membered cyclic alcohols and ketones are converted into their dicarboxylic acids in high yields and in short reaction times employing the same reaction protocol. The synergy between the WO3 and ionic liquid is assumed to play a significant role towards its very high catalytic activity. The recyclability of the catalyst is proved to be noteworthy as the catalyst exhibits no significant change in its catalytic activity even after five cycles of reuse.

Facile Solvothermal Synthesis of Novel CuCo2S4/g-C3N4 Nanocomposites for Visible-Light Photocatalytic Applications

In this work, we synthesized a series of CuCo2S4/g-C3N4 (CSC) nanocomposites by a facile solvothermal approach using D-penicillamine as sulphur source. The phase structure, morphology, chemical composition, and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activities of the synthesized CSC nanocomposites were evaluated using degradation of methylene blue (MB) dye under visible-light irradiation. The light absorption capacity and photocatalytic activity of CuCo2S4 were enhanced by the successful incorporation with g-C3N4. The nanocomposite with 30% loading of g-C3N4 in CuCo2S4 exhibited maximum degradation efficiency compared to the pure CuCo2S4 towards the degradation of MB dye under the light irradiation. A possible mechanism for enhanced photocatalytic activity towards the pollutant degradation by the nanocomposites was proposed.