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Research Papers

  • The rapid industrial growth has led to the large production of oily wastewater. Treatment of oily wastewater is an inevitable challenge to manage the greater demand of clean water for the rapidly growing population and economy. In the present work, we have developed a smart surface mesh with reversible wetting properties via a simple, ecofriendly, and scalable approach for on-demand oil–water separation. ZnO nanowires (NWs) obtained from the chemical vapor deposition method were coated on a stainless steel (SS) mesh. The as-synthesized ZnO-NWs-coated mesh shows superhydrophilic/underwater superoleophobic behavior. This mesh works in “water-removing” mode, where the superhydrophilic as well as underwater superoleophobic nature allows the water to permeate easily through the mesh while preventing oil. The wetting property of ZnO-NWs-coated mesh can be switched easily from …

  • Photomechanical actuation is the conversion of light energy into mechanical energy through some smart materials. Infrared-responsive smart materials have become an emerging field of research due to easy availability and eco-friendly nature of their stimulus in the form of sunlight, which contains about 50% of near-infrared(nIR) making these materials useful at macro-scale photoactuator applications. Here, we demonstrate fabrication of highly versatile nIR triggered photoactuators based on graphene oxide/polycarbonate bilayers that offers fast, low-cost fabrication, large deflection, reversible actuation and wavelength-selective response. The photoactuators are realized by vacuum filtration of graphene oxide/water dispersion through polycarbonate membrane resulting graphene oxide/polymer bilayer structure. The photoactuation response was measured in the form of deflection from equilibrium position as a …

  • We demonstrate the fabrication of highly versatile photomechanical actuators based on graphene-polymer/metal bilayers that offers fast, low-cost fabrication, large deflection, reversible actuation under zero applied pre-strain, and wavelength-selective response. The photomechanical actuator consists of a graphene nanoplatelet (GNP)-polydimethylsiloxane (PDMS) nanocomposite with a thin chromium metal coating of 35 nm thickness on the backside of the structure. The photomechanical response of the GNP-PDMS/Cr photomechanical actuator was measured by recording the variation of the bending angle upon infrared (IR) light illumination. The bending in the bilayer actuator is caused by the generation of thermal stress due to the large mismatch (the ratio being 1/20) of the thermal expansion coefficient between the two layers as a result of IR absorption by GNPs and a subsequent increase in the local …

  • Herein, we report an intelligent mesh for dual mode reversible separation of immiscible heavy/light oil water mixture and both oil-in-water as well as water-in-oil emulsions. ZnO nanowires coated stainless steel mesh with pore size 50 μm and 10 μm were fabricated successfully. The wettability of mesh can be reversibly switched between “oil-blocking” and “water-blocking” modes by alternatively annealing the smart mesh at about 210 °C for about 20 min in presence of poly (dimethyl siloxane) vapors and at 300 °C for 25 min in air, respectively. The “oil-blocking” mode was suited for the efficient separation of light oil/water mixture and oil-in-water emulsion, while “water-blocking” mode was found to be suitable for the separation of heavy oil/water mixture and water-in-oil emulsion. This work provides a simple, cost effective, eco-friendly and time saving approach applicable for separation of both form of oil/water …

  • Zig-Zag Ag2S nanostructures for superior optical absorption and photoelectrochemical water splitting performance

    with Jyoti Yadav, Parul Raturi, Sarjana Yadav, J. P. Singh *

    Here, we report synthesis of AgS nanostructures of zig-zag geometry to achieve the improved photoelectrochemical (PEC) water splitting response for hydrogen generation. A two-step process was utilized for the fabrication of working electrodes. The synthesis of zig-zag nanorods was carried out using glancing angle deposition followed by sulfurization. The PEC performance was studied by varying the number of zig-zag arms of AgS. The as-prepared four arm AgS zig-zag electrodes exhibited superior optical absorption, as well as photocurrent density of 3.04 mA/cm2 (at 1 V vs Ag/AgCl), compared to one arm AgS nanorods with minimum charge transfer resistance at the semiconducting electrode/electrolyte interface. The improved photocurrent density of four arm AgS zig-zag nanorods electrode was attributed to increased optical trapping and hence, effective absorption of light due to its wavy structure. The …

  • In the present work, we have investigated the oil and water wetting properties of strontium titanate nanoparticles. The as-synthesized nanoparticles were coated on the stainless steel mesh to investigate wetting properties. The coated mesh was found to have superhydrophilic and superoleophilic behavior with a contact angle value of nearly zero degree for both water as well as oil. Further underwater oil contact angle was measured, showing underwater superoleophobic behavior of the coated mesh. The underlying mechanism was studied for the wetting behavior of strontium titanate coated mesh. The coated mesh was then utilized for the gravity-driven separation of different oil/water mixtures. The separation mesh can be used multiple times showing its antifouling property along with recyclability. Further, a capillary pressure based model was developed to explain the wettability contrast for water and oil as well as …