Boor Singh Lalia

Fog-harvesting potential of lubricant-impregnated electrospun nanomats.

Hydrophobic PVDF-HFP nanowebs were fabricated by a facile electrospinning method and proposed for harvesting fog from the atmosphere. A strong adhesive force between the surface and a water droplet has been observed, which resists the water being shed from the surface. The water droplets on the inhomogeneous nanomats showed high contact angle hysteresis. The impregnation of nanomats with lubricants (total quartz oil and Krytox 1506) decreased the contact angle hysteresis and hence improved the roll off of water droplets on the nanomat surface. It was found that water droplets of 5 μL size (diameter = 2.1 mm) and larger roll down on an oil-impregnated surface, held vertically, compared to 38 μL (diameter = 4.2 mm) on a plain nanoweb. The contact angle hysteresis decreased from ~95 to ~23° with the Krytox 1506 impregnation.

Electrospun metallic nanowires: Synthesis, characterization, and applications

Metals are known to have unique thermal, mechanical, electrical, and catalytic properties. On the other hand, metallic nanowires are promising materials for variety of applications such as transparent conductive film for photovoltaic devices, electrodes for batteries, as well as nano-reinforcement for composite materials. Whereas varieties of methods have been explored to synthesize metal nanowires with different characteristics, electrospinning has also been found to be successful for that purpose. Even though electrospinning of polymeric nanofibers is a well-established field, there are several challenges that need to be overcome to use the electrospinning technique for the fabrication of metallic nanowires. These challenges are mainly related to the multi-steps fabrication process and its relation to the structure evolution of the nanowires. In addition to reviewing the literature, this article identifies promising avenues for further research in this area with particular emphasis on the applications that nonwoven metal wires confined in a nano-scale can open.

Photocatalytic activity of an electrophoretically deposited composite titanium dioxide membrane using carbon cloth as a conducting substrate

This is the first report where a polymer, namely poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP), has been used as a binder together with the electrophoretic deposition process. PVDF–HFP provided mechanical stability and membrane flexibility and, at the same time, eliminated the leaching of the electrophoretically deposited TiO2 particles in the solution during the water treatment process. Electrophoretic deposition of TiO2 particles containing different weight percentages of PVDF–HFP were conducted and the required concentration of PVDF–HFP in the solution to prevent the leaching of TiO2 was established. The obtained material finds applications in photocatalytic water treatment, as investigated under simulated solar light in aqueous solutions using 4-nitrophenol, caffeine, acetaminophen and uracil as target molecules. Results indicated the complete removal of 4-nitrophenol after 24 hours, a degradation percentage above 80% of acetaminophen and uracil and 60% for caffeine. Photodegradation of pre-adsorbed methylene blue (MB) both under simulated solar radiation and visible light was successfully achieved in dry conditions as confirmed by diffusion reflectance spectra.

Carbon nanostructures modified LiFePO4 cathodes for lithium ion battery applications: optimized porosity and composition

Lithium iron phosphate (LiFePO4) battery cathode was fabricated without using any metallic current collector and polymeric binder. Carbon nanostructures (CNS) were used as microbinders for LiFePO4 particles and at the same time as a 3D current collector. A facile and cost effective method of fabricating composite cathodes of CNS and LiFePO4 was developed. Thick electrodes with high loading of active material (20?25 mg cm?2) were obtained that are almost 2?3 folds higher than commercial electrodes. SEM images confirm that the 3D CNS conductive network encapsulated the LiFePO4 particles homogenously facilitating the charge transfer at the electrode?CNS interface. The composition, scan rate and porosity of the paper-like cathode were sequentially varied and their influence was systematically monitored by means of linear sweep cyclic voltammetry and AC electrochemical impedance spectroscopy. Addition of CNS improved the electrodes bulk electronic conductivity, mechanical integrity, surface area and double layer capacitance, yet compromised the charge transfer resistance at the electrode?electrolyte interface. Based on a range of the tested binder-free electrodes, this study proposes that electrodes with 20 wt% CNS having 49???2.5% porosity had realized best improvements of two folds and four folds in the electronic conductivity and diffusion coefficient, respectively.