Chalcogenide nanocomposite electrodes grown by chemical etching of Ni-foam as electrocatalyst for efficient oxygen evolution reaction

We report on the synthesis of NiSSe nanocomposite by chemical etching of Ni-foam using simple solvothermal technique and investigated it as an electrocatalyst for the oxygen evolution reaction (OER). Different morphologies such as nanograins, branched mesh-like architecture, and agglomerated nanograins with nanoporous are obtained for NiSSe, NiSe, and NiS, respectively. The overpotentials of 247, 266, and 329 mV (vs RHE) are obtained to attain a current density of 30 mA cm⁻² for NiSSe, NiS, and NiSe nanocomposites, respectively. Interestingly, ternary nanocomposite reaches a high current density of 100 mA cm⁻² by operating only at an overpotential of 342 mV. The low Tafel slope of 175.7 mV dec⁻¹ reveals that the ternary nanocomposite consists of most favorable catalytic kinetics for mass and electron transport during the OER reaction. The improved catalytic performance of NiSSe nanocomposite is attributed to the synergy between electrochemcial surface area and improved electronic conductivity.     

Deposition of Thin Lipid Films Prepared by Electrospraying

An efficient way to apply coatings on complex surfaces is electrospraying. We report on coating of porous model surfaces with well-defined properties using a multiple nozzle electrospraying system to spray sunflower oil and butter-based coating materials. Selected model surfaces were nickel membranes with large rectangular straight-through pores (13 μm width), polyether sulfone membranes (PES) with small, interconnected pores (0.2 μm) and dense cellulose membranes. The coating materials penetrated the pores of PES and nickel membranes, filling them up and thereby significantly decreasing the water vapour permeation flux through the substrate. Once the pores were (partially) filled, application of additional coating material caused only minor further flux reduction. For the cellulose membrane, the materials accumulated on the membrane surface; the resulting reduction in water vapour permeation rate was much lower as for the other membranes. Surface coverage during deposition was simulated using a Monte Carlo approach and appeared in agreement with experimental values at lower amounts of applied coating material (<0.03 kg/m²). After deposition of larger amounts, using repeated electrospraying, the water vapour permeation flux reduction was larger than expected from the simulations. This was explained by re-melting and fusion of droplets, which indicated that repeated electrospraying of lipids could be an attractive method to create thin coatings with excellent barrier properties for, e.g. foods and pharmaceuticals that typically have such complex, porous surfaces.     

Electrochemical investigations on spray deposited tin oxide thin films

Tin oxide (SnO₂) thin films were prepared by a simple and inexpensive spray pyrolysis technique from an aqueous solution at various substrate temperatures viz. 300, 400 and 500 °C, and their electrochemical studies have been carried out. The thin films have been optically and electrochemically characterized by means of transmittance, cyclic voltammetry and chronoamperometry. The mechanism of reduction and oxidation reactions that took place during the potential cycling is presented. The samples deposited at 500 °C exhibit better performance in terms of coloration efficiency, reversibility, contrast ratio and response time.     

Strong photo-response in a flip-chip nanowire p-Cu2O/n-ZnO junction

Cu(2)O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing ambient annealing protocol. ZnO nanorods are grown on ITO coated glass by a low temperature chemical route. The electronic and photo-response properties of the p-Cu(2)O/n-ZnO flip-chip heterojunction are then studied and analyzed. We show that the I-V characteristic is rectifying and the junction exhibits a good photoresponse (～120% under 1 V reverse bias) under AM 1.5 (1 Sun) illumination. This nano-heterojunction photo-response is far stronger as compared to that of a pulsed laser deposited thin film p-Cu(2)O/n-ZnO heterojunction, which can be attributed to higher junction area in the former case.     

Effect of post annealing treatment on electrochromic properties of spray deposited niobium oxide thin films

Niobium oxide thin films were deposited on the glass and fluorine doped tin oxide (FTO) coated glass substrates using simple and inexpensive spray pyrolysis technique. During deposition of the films various process parameters like nozzle to substrate distance, spray rate, concentration of sprayed solution were optimized to obtain well adherent and transparent films. The films prepared were further annealed and effect of post annealing on the structural, morphological, optical and electrochromic properties was studied. Structural and morphological characterizations of the films were carried out using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques. Electrochemical properties of the niobium oxide thin films were studied by using cyclic-voltammetry, chronoamperometry and chronocoulometry.     

Spray deposited titanium oxide thin films as passive counter electrodes

Titanium dioxide (TiO₂) thin films were deposited from methanolic solution onto fluorine doped tin oxide coated conducting glass substrates by spray pyrolysis technique. The electrochemical properties of TiO₂ thin films were investigated using cyclic voltammetry, chronoamperometry, chronocoulometry and iono-optical studies, in 0.1N H₂SO₄ electrolyte. Performance of the films deposited at three different substrate temperatures, viz. 350, 400 and 450 °C is discussed in view of their utilization in electrochromic devices, as counter electrode. The magnitude of charge storage capacity, Q/t (4.75-6.13 × 10⁻³ mC/(cm² nm)) and colouration efficiency (3.2-4.3 cm²/mC) of TiO₂ rank these films among the promising counter electrodes in electrochromic devices.     

Electrochromism in composite WO<Subscript>3</Subscript>–Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> thin films synthesized by spray pyrolysis technique

Composite WO₃–Nb₂O₅ thin films were deposited on the glass and fluorine-doped tin oxide (FTO)-coated glass substrates using simple and inexpensive spray pyrolysis technique. The process parameters, like nozzle-to-substrate distance, spray rate, concentration of sprayed solution, etc., were optimized to good quality films. The films were characterized for the structural, morphological, optical, and electrochromic properties. Structural and morphological characterizations of the films were carried out using scanning electron microscopy and X-ray diffraction techniques. Electrochemical properties of the Composite WO₃–Nb2O₅ thin films were further studied using cyclic-voltammetry, chronoamperometry, chronocoulometry, and electrochemical Impedance spectroscopy.     

Comprehensive Review on Silicon-enhanced Green Nanocomposites Towards Sustainable Development

Silicon - The demand for the development of high-performance and eco-friendly nanocomposites is soaring up. This is because of their desired mechanical, thermal, electrical, magnetic, catalytic,...     

Synthesis and characterization of zinc stannate thin films prepared by spray pyrolysis technique

The zinc stannate thin films were synthesized by simple and inexpensive spray pyrolysis technique on the glass and fluorine doped tin oxide coated conducting glass substrates. The as deposited films were further annealed at 500 °C temperature for 12 h. The structural optical and morphological characterization of as prepared and annealed films was carried out by XRD, UV–Vis spectroscopy, SEM and AFM techniques respectively. The structural analysis shows that films are polycrystalline and crystallized in cubic inverse spinel crystal structure. SEM studies show that grain size increases after annealing and exhibits spherical morphology. AFM study shows that roughness is higher for the post annealed film. Further the samples were tested for testing their applicability for dye sensitized solar cells. The as prepared, annealed and CNT doped samples exhibits photoconversion efficiencies 2.7, 2.8 and 3.1 % respectively.