Polyol-mediated zinc oxide nanoparticles using the refluxing method as an efficient photocatalytic and antimicrobial agent

Nanomaterials have attracted more curiosity recently because of their wide-ranging application in environmental remediation and electronic devices. The current study focuses on zinc oxide nanoparticles’ (ZnO NPs) simple production, characterization, and applications in several fields, including medicinal and photocatalytic degradation of dyes. The non-aqueous-based reflux method is helpful for ZnO NP synthesis; the procedure involves refluxing zinc acetate dihydrate precursor in ethylene glycol for 3 hours in the absence of sodium acetate, in which the refluxing rate and the cooling rate are optimized to get the desired phase, and the unique morphology of polyol-mediated ZnO NPs; it has been achieved using the capping agent TBAB (tetra-butyl ammonium bromide) and precursor zinc acetate dihydrate. UV–Vis, FTIR, XRD, and FESEM structurally characterized polyol-mediated ZnO-NPs. The results show that the material is pure and broadly aggregated into spherical nanoparticles with an average particle size of 18.09 nm. According to XRD analysis, heat annealing made the crystallites more prominent and favored a monocrystalline state. These results and the low cost of making polyol-mediated ZnO NPs demonstrate photocatalytic and antimicrobial properties

Hybrid AgNP–TiO2 thin film based photoanode for dye sensitized solar cell

This article addresses two major issues in the plasmonic dye solar cell; (i) protection of plasmonic nanoparticles from electrolyte attack and (ii) design of appropriate molecular dye to harvest photon near the plasmonic resonance. This report reveals the synthesis of D-π-A carbazole dye and incorporation of plasmonic Ag nanoparticles (AgNPs) into TiO2 film using Ag–TiO2 gel. We have designed and synthesized an efficient D-π-A carbazole dye molecule whose absorption maxima matches the plasmonic resonance of AgNPs leading to augmented near field effect, enhancing photon harvesting property of dye molecule. This article also describes a strategy to incorporate AgNPs into the TiO2 photoelectrode by Ag–TiO2 gel. The plasmonic photoanode was characterized using SEM and optical spectroscopy. Dye solar cells were characterized by J–V characteristics and electrochemical impedance technique in order to take insight into photovoltaic performance and electron transfer kinetic. This engineered DSSC achieves 45% enhancement in current due to the plasmon enhanced near field effect at thin film (3 μm)

Structured Growth of Metal–Organic Framework MIL-53(Al) from Solid Aluminum Carbide Precursor

The conventional synthesis of metal–organic frameworks (MOFs) through soluble metal-salt precursors provides little control over the growth of MOF crystals. The use of alternative metal precursors would provide a more flexible and cost-effective strategy for direction- and shape-controlled MOF synthesis. Here, we demonstrate for the first time the use of insoluble metal–carbon matrices to foster directed growth of MOFs. Aluminum carbide was implemented as both the metal precursor and growth-directing agent for the generation of MIL-53­(Al). A unique needle-like morphology of the MOF was grown parallel to the bulk surface in a layer-by-layer manner. Importantly, the synthesis scheme was found to be transferrable to the production of different linker analogues of the MOF and other topologies. Given the variety of metal carbides available, these findings can be used as a blueprint for controlled, efficient, and economical MOF syntheses and set a new milestone toward the industrial use of MOFs at large-scale

Functionalized membranes for membrane chromatography

The focus of this thesis is synthesis and quantification of homopolymer and block copolymer grafts and understanding controlled polymer growth. The homopolymer and block copolymer grafts were synthesized through sequential cationic polymerization of styrene and substituted styrene monomers chloromethylstyrene (CMS) and 4-ethoxystyrene (ES) in the pores of microfiltration polyethersulfone (PES) membrane. Polymer growth aspects like kinetics of reaction, amount of monomer reacted, ion-exchange capacity (IEC), and graft length were studied with respect to initiator contact time and monomer feed concentration. Functionalization of the microfiltration membrane was achieved by a two step procedure. The first step was to introduce sulfonic acid initiator sites by mild sulfonation with 0.5N H2SO4. This was followed by cycling through each type of monomer solution (styrene and substituted styrenes). Successful introduction of homopolymer and block copolymer grafts was confirmed by material balances on the monomer/toluene permeate solutions. Analytical techniques used for quantification of polymer grafting include UV-Visible spectroscopy, gas chromatography and atomic absorption. The functionalized membrane showed a steep decrease in membrane permeability compared to the raw membrane indicating the presence of polymeric chains in the membrane flow path. Functionalized membranes prepared by this method have as many as 125 repeat units per chain. Given the initiator concentration, this equates to an IEC of 4.9 meq/g, indicating high dynamic and equilibrium binding capacity. Pseudo-first-order kinetic expression correlated well with the experimental data for each monomer reacted. At lower initiator surface density, graft length and IEC were impacted by both monomer feed concentration and initiator contact time. However, for higher initiator surface density, monomer feed concentration parameter dominates. Block copolymer formation is the first step to synthesizing an analog of the phenylalanine/tyrosine dipeptide structure in protein A, which is shown in literature for selective adsorption of immunoglobulin G (IgG). This work will lead to further development of functionalized membranes as membrane adsorbers for high throughput production of monoclonal antibodies for new cancer therapies. In addition, it will lead to discoveries in sequential polymerization to generate customized structures and design of synthetic affinity ligands. (Published By University of Alabama Libraries

Anisotropic One-Dimensional Aqueous Polymer Gel Electrolyte for Photoelectrochemical Devices: Improvement in Hydrophobic TiO₂–Dye/Electrolyte Interface

Aqueous photoelectrochemical devices have emerged recently as promising area because of their economic and ecological friendliness. In the present work, we have expedited surface active amphiphilic quasi-solid aqueous polymer gel electrolyte (PGE) with hydrophobic sensitizer SK3 in water-based dye sensitized solar cell (DSSC). PGE was prepared from amphiphilic block copolymer (PEO)–(PPO)–(PEO) with iodide–triiodide couple in pure aqueous media without any organic solvent. This block copolymer, with iodide-triiodide salt exhibits 1D-lamellar microcrystalline phase which shows stability in the temperature range of 25–50 °C. Parallel (||^al) and perpendicular (⊥^ar) alignment of anisotropic lamellar microcrystalline phase pertaining by PGE were characterized and applied in quasi-solid DSSC. Temperature dependency of ionic conductivity, triiodide diffusion, differential scanning calorimetry, viscosity, and 1-D lamellar anisotropic behavior were studied. Surface active effect of PGE at the hydrophobic dye sensitized photoanode was investigated and compared with liquid water based electrolyte. Because of the amphiphilic nature and thermoreversible sol–gel transition of PGE at a lower temperature (0 to −2 °C) allowing PGE to penetrate efficiently inside the hydrophobic surface of dye–TiO₂ and resulted in a fused contact between dye–TiO₂/PGE interface. This aqueous PGE successfully enhances the performance of DSSCs over liquid water based devices by improving their <i>V</i>_oc and stability. Under 0.5 sun illumination, DSSC with 1-D lamellar perpendicularly align PGE shows an efficiency of 2.8% and stability up to 1000 h at 50 °C