Photocatalytic degradation of fluoroquinolone antibiotics using chitosan biopolymer functionalized copper oxide nanoparticles prepared by facile sonochemical method.

Photocatalytic degradation is an excellent method for removing pharmaceutical residues due to their simplicity, ecological benignity, high efficiency, and exceptional stability. Herein, we demonstrate the sonochemically synthesised chitosan biopolymer functionalized copper oxide nanoparticles as an efficient photocatalyst for the degradation of fluoroquinolone-based antibiotics. The X-ray diffraction Rietveld refinement revealed the formation of single-phase copper oxide (CuO) with a monoclinic structure. The presence of biopolymer functionalization was corroborated by Fourier Transform Infrared spectroscopy by observing the -NH2 and -OH functional groups. The high-resolution transmission electron microscopic images inferred that Chitosan functionalized copper oxide (C-CuO) particles are nano-sized with a smooth texture and aggregation-free particles. The strong absorbance and the broad photoluminescence emission in the ultraviolet-visible region confirm the suitability of CuO and C-CuO nanoparticles for photocatalytic applications. The catalytic activity was studied against fluoroquinolone-based antibiotics such as ciprofloxacin and norfloxacin under direct sunlight illumination. Interestingly, the C-CuO catalyst demonstrated 71.07 % (@140 min.) and 71.9 % (@60 min.) of degradation for ciprofloxacin and norfloxacin, respectively. The obtained photocatalytic activity of the prepared CuO and C-CuO catalysts was superior to the CuO particles prepared by the coprecipitation method (CC-CuO).

Studies on the Synthesis and Physico-Chemical Properties of Porous LiFe0.9M0.1P2O7 (M = Fe, Co, Mn, Ni) Nanoparticles.

The nano-porous LiFe0.9M0.1P2O7 (M = Fe, Co, Mn, Ni) particles were successfully prepared by simple microwave assisted combustion method and studied its detailed physico-chemical properties. The phase purity, crystallinity, functional group identification was revealed through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. The presence of nanoporous was identified through transmission electron microscopic (TEM) images. The electrical conductivity results illustrated that LiFe0.9Ni0.1P2O7 has higher conductivity (2.85 x 10⁻7 S cm⁻¹) among the studied systems owing to their negligible grain boundary effect. The normal dielectric behaviour was observed for all the LiFe0.9M0.1P2O7 (M = Fe, Co, Mn, Ni) materials. The paramagnetic behaviour and the Fe³âº state of LiFe0.9M0.1P2O7 were obtained from VSM and Mössbauer spectral analysis respectively. The cyclic voltammogram suggested that the good electrochemical lithium intercalation/de-intercalation behaviour of LiFe0.9M0.1P2O7 (M = Fe, Co, Mn, Ni) electrodes in aqueous electrolytes. The obtained diffusion coefficient value is comparable with carbon based materials.

Impact of Si4+ Ions Doping on the Electrochemical Cycling Performance of NiTiO3 as Anodes for Li-Lon Batteries.

Pristine and Si4+ doped NiTiO3 are successfully synthesized by molten salt method and electrochemically characterized for its use as an anode material for Li-ion batteries. The X-ray diffraction (XRD) results enumerates that the lattice parameter and the cell volume decreases upon the addition of Si4+ due to its smaller ionic radius. The presence of Si4+ in NiTiO3 structure was also confirmed using FTIR analysis, which showed the stretching vibrations of Si-O at -1008 cm(-1). The SEM images reveal that the NiTiO3 particles are in micrometer range and the size of the particle is found to be decrease after Si4+ addition. The electrical studies infers an enhancement in the conductivity from 4.4 x 10(-7) S x cm(-1) to 1.7 x 10(-6) S x cm(-1) on dopant addition. The initial discharge capacity of NiTiO3 is found to be 1257 mA h g(-1) and there is a capacity fading on consecutive cycles. NiTi0.9Si0.1O3 enhances the cyclic performances and a constant capacity around 400 mA h g(-1) is maintained, a very good reversibility with almost 100% efficiency is observed elucidating the fact that almost all the Li ions intercalated are successfully de-intercalated during the discharge process.

Nanocrystalline Pyrochlore La2Sn1.6Zr0.4 as a New Candidate for Supercapacitor Electrodes.

Nanocrystalline La2Sn1.6Zr0.4O7 is synthesized by microwave assisted combustion method. The phase formation and morphological features of La2Sn1.6Zr0.4O7 are characterized by X-ray diffrac- tion (XRD), X-Ray photoelectron spectroscopy (XPS), Fourier Transform Infrared (FT-IR) spectrum and Transmission Electron Microscopy (TEM) respectively. XRD pattern shows the formation of cubic Pyrochlore structure of La2Sn1.6Zr0.4O7. FTIR studies attributed the presence of characteristic functional groups of La-O, Sn-O and Zr-O. TEM image reveals that the size of La2Sn1.6Zr0.4O7 particle exhibits from 50 nm to 100 nm and the observed d-spacing from HRTEM is matched well with the XRD d-spacing. The SAED pattern shows the polycrystalline behaviour of La2Sn1.6Zr0.4O7. The room temperature electrical conductivity of La2Sn1.6Zr0.4O7 is 3.12 x 10(-6) S cm(-1). The synthe- sized La2Sn1.6Zr0.4O7 particle is explored as electrodes for supercapacitor and the performances are studied by cyclic voltammetric and charge discharge studies using 1 M H2SO4 electrolyte. From charge-discharge analysis the specific capacitance was found to be 74 Fg(-1) at 1 mA cm(-2). The resistive behaviour of the electrodes is studied through electrochemical impedance spectroscopy. Also the cycling stability is studied by performing the 100 charge-discharge cycles. It reveals that there is almost 100% cycling stability is achieved. Hence nanocrystalline La2Sn1.6Zr0.4O7 pyrochlore can have the feasibility as an electrode material for supercapacitor application.

High performance solid-state electric double layer capacitor from redox mediated gel polymer electrolyte and renewable tamarind fruit shell derived porous carbon.

The activated carbon was derived from tamarind fruit shell and utilized as electrodes in a solid state electrochemical double layer capacitor (SSEDLC). The fabricated SSEDLC with PVA (polyvinyl alcohol)/H2SO4 gel electrolyte delivered high specific capacitance and energy density of 412 F g(-1) and 9.166 W h kg(-1), respectively, at 1.56 A g(-1). Subsequently, Na2MoO4 (sodium molybdate) added PVA/H2SO4 gel electrolyte was also prepared and applied for SSEDLC, to improve the performance. Surprisingly, 57.2% of specific capacitance (648 F g(-1)) and of energy density (14.4 Wh kg(-1)) was increased while introducing Na2MoO4 as the redox mediator in PVA/H2SO4 gel electrolyte. This improved performance is owed to the redox reaction between Mo(VI)/Mo(V) and Mo(VI)/Mo(IV) redox couples in Na2MoO4/PVA/H2SO4 gel electrolyte. Similarly, the fabricated device shows the excellent capacitance retention of 93% for over 3000 cycles. The present work suggests that the Na2MoO4 added PVA/H2SO4 gel is a potential electrolyte to improve the performance instead of pristine PVA/H2SO4 gel electrolyte. Based on the overall performance, it is strongly believed that the combination of tamarind fruit shell derived activated carbon and Na2MoO4/PVA/H2SO4 gel electrolyte is more attractive in the near future for high performance SSEDLCs.