Jay Prakash Pandey

Sol-gel derived spinel MxCo3−xO4 (M=Ni, Cu; 0≤x≤1) films and oxygen evolution ☆

Spinel-type binary transition metal oxides of cobalt and nickel (or copper) with composition MxCo3−xO4 (where M=Ni, Cu; 0≤x≤1) were synthesized in film forms by a sol-gel route and their physicochemical and electrocatalytic properties have been investigated using SEM, XRD, cyclic and stationary voltammetries. The roughness factors, RF, of electrodes made of these films were determined by AC-impedance and cyclic voltammetry (CV). The two procedures compared well, and enabled the discrimination between apparent and true (real) electroactivity towards the oxygen evolution reaction (OER). Intermediate compositions showed a higher activity despite a lower real surface area, and laboratory tests at 70°C in 30 wt% KOH good practical performances.

Preparation and characterization of thin films of LaNiO3 for anode application in alkaline water electrolysis

LaNiO3 electrodes were prepared, in the form of thin films on platinum by the methods of spray pyrolysis and sequential coating of mixed metal nitrate solutions followed by thermal decomposition. The films were adherent and of p-type semiconducting. Cyclic voltammetric studies indicated the formation of a quasireversible surface redox couple, Ni(iii)/Ni(ii), on these films before the onset of oxygen evolution in 1 m KOH. The anodic Tafel slopes were ∼40 and ∼65 mV decade−1, on the sprayed LaNiO3 film and on the film obtained by a layer method, respectively. The reaction order with respect to OH− was found to be 2.2 on the sprayed oxide film and 1.2 on the layer film. The sprayed oxide film was found to be electrocatalytically more active. It is suggested that the oxygen evolution reaction proceeds on both the film electrodes via the formation of the physisorbed H2O2 as an intermediate in the rate determining step.

Voltammetric Studies of Some Oxo‐Uranium (VI) Complexes of Dithio Ligands at Thin Film Semiconducting ZnO / Acetonitrile Interface for Photosensitizer Applications

Le comportement redox de deux complexes oxo duranium(VI) dans leur etat fondamental est etudie par voltammetrie cyclique dans lacetonitrile avec une electrode a couche mince doxyde de zinc afin de tester leur interet comme materiau photosensible

Extension of the spectral response of sprayed ZnO thin film electrodes induced by nickel and cobalt doping

In this work the influence of the dopants Ni and Ni+Co on the photoresponse of sprayed ZnO thin film electrodes in acetonitrile solution was studied. In the case of an Ni-doped ZnO electrode, the photocurrent spectrum showed the extension up to a wavelength of light of 580 nm, while the (Ni+Co)-doped electrode exhibited an extension up to around 700 nm. These extensions are attributed to the dopant energy bands lying in the bandgap region of ZnO.

Spectral sensitization of sprayed thin filmn-ZnO electrodes by 4-p-dimethylaminobenzylidene-1,2-diphenyl-2-imidazoline-5-one in acetonitrile solution

A photoelectrochemical cell based on a thin filmn-ZnO electrode sensitized by 4-p-dimethylaminobenzylidene-1,2-diphenyl-2-imidazoline-5-one (subsequently referred to as 5-imidazolone) has been studied in acetonitrile medium using hydroquinone as supersensitizer. The redox behaviour of 5-imidazolone at Pt and ZnO electrodes has been studied in the same medium through cyclic voltammetry. The redox potentials of 5-imidazolone coupled with the flat-band potential of the ZnO electrode (obtained from the potential for photocurrent onset) have been used to determine their respective energy levels. Transient open circuit photovoltage-time profile and transient photocurrent-time profiles at fixed biased potentials have been recorded to determine the obtainable photovoltage and photoresponse behaviour of the ZnO electrode in the presence of 5-imidazolone. The quantum efficiency of the sensitized photocurrent was found to be ∼7% at 455 nm (λmax), the wavelength of monochromatic light. The long-term stability of the ZnO electrode in the medium of investigation was tested in the presence of this compound and was found to give a quite stable photocurrent for 10 h of continuous operation at lower light intensity. The power efficiency of ZnO/5-imidazolone in a acetonitrile/Pt photocell was also determined without any external applied potential.

Sesbania gum based hydrogel as platform for sustained drug delivery: An ‘in vitro’ study of 5-Fu release

The purpose of this study is to fabricate 5-Fluorouracil sustained release matrix based on a novel, nontoxic, eco-friendly modified biopolymer. The sesbania gum based hydrogel has been prepared by microwave assisted method using acrylamide as a monomer and N,N Methylenebisacrylamide as a crosslinker. The crosslink copolymerization has been confirmed by several modern techniques such as FTIR, SEM, XRD, TGA, DSC, elemental analysis etc. The bioactive 5-Fluorouracil has been encapsulated via solvent swelling method and its release rate has been investigated in various pH dissolution medium through USP standard protocol. The synthesized hydrogel with higher degree of crosslinking exhibited slower release rate than that of hydrogel having lower degree of crosslinking. Thus, resulting higher t25 value, the release rate increases with increase in pH of the medium. Release kinetics suggests the non-Fickian release behaviour of the hydrogel.

A Novel Biodegradable Cinnamic Acid Grafted Carboxymethyl Cellulose Based Flocculant for Water Treatment

Cinnamic acid grafted carboxymethyl cellulose (CMC-g-P (CA)) has been synthesized by microwave assisted technique, which is an alliance of microwave radiation with chemical free radical initiator (CAN) to commence grafting. The novel graft copolymer has been characterized by physicochemical techniques – FTIR spectroscopy, intrinsic viscosity measurement, elemental analysis (C, H and N), SEM micrograph and TGA study. The flocculation efficacy and range of turbidity during the sedimentation stage for synthesized material has been investigated in kaolin suspension by ‘Jar test’ procedure. The optimal dosage of CMC-g-P (CA) as flocculant in kaolin suspension is at 10 ppm and it showed lowest range of turbidity (176-61 NTU) during sedimentation stage.

Photoelectrochemistry of ZnO thin film electrode sensitized by an oxouranium (VI) complex in an acetonitrile photocell

The photosensitizing ability of tetraethylammoniumbis-(isomaleonitrilo) dioxouranate(VI), (Et4N)2[UO2(i-MNT)2], studied at then-ZnO/acetonitrile interface, is shown by the enhancement observed in photocurrent with (Et4N)2[UO2(i-MNT)2] in comparison to that obtained without the sensitizer. The flat-band potential is −0·40V vs SSCE. (Et4N)2[UO2(i-MNT)2] acts as an acceptor-type sensitizer as concluded from the energy-level diagram constructed using its redox potential coupled with its excitation energy and the flat-band potential of ZnO electrode. Long-term stability of the photocurrent under continuous illumination of the electrode is also studied.

Biosorptive removal of arsenite and arsenate from aqueous medium using low-cost adsorbent derived from ‘Pods of green peas’: Exploration of kinetics, thermodynamics and adsorption isotherms

The present work explores the biosorption characteristics of pods of green peas (PGP) for arsenite [As(III)] and arsenate [As(V)] removal from aqueous medium. Optimization of adsorption parameters like contact time, arsenic concentration, temperature, biosorbent dose and pH through batch mode of experiments was studied. Among the different isotherm models, Langmuir for As(III) and Temkin for As(V) provided the best fit for the obtained data of arsenic sorption onto PGP. D-R mean free energy (E) indicates the process is physisorption. Thermodynamics studies were found to be endothermic, feasible and spontaneous. Kinetically, adsorption follows the pseudo-second-order kinetics in sorption of As(III) and As(V) both. The desorption studies of exhausted PGP show 81% of As(III) and 72% of As(V) could be leached out. Reusability of biosorbent up to 7th cycles of incessant operation supports their commercial importance with very little effects of common ions on sorption capacity.

Grafted sesbania gum: A novel derivative for sugarcane juice clarification

This work describes the significance of graft copolymer induced flocculation process in sugarcane juice clarification. The naturally occurring cinnamic acid has been successfully incorporated into the structure of sesbania gum through microwave assisted technique (hybrid of conventional and microwave based method) to develop novel, non-toxic, eco-friendly product with highly extended structure. The customized structure of gum derivative has been characterized by a number of modern techniques like 13C NMR, FTIR, SEM, XRD, TGA, DSC, elemental and viscometric analysis. The separation of suspended colloidal impurities from cane juice has been achieved through the application of synthesized gum derivative as a flocculant. The clarification performance of the graft copolymer has been evaluated in terms of turbidity, absorbance, and degree brix (°bx). The flocculant exhibited maximum efficiency at 1.0ppm (optimized dose) without altering the nutritional parameters (% sugar content). The clarified juice thus obtained may be used as a beverage for direct consumption or for the manufacture of white sugar.