Smart and robust electrospun fabrics of piezoelectric polymer nanocomposite for self-powering electronic textiles

The present work designs a piezoelectric nanogenerator (PENG) based on the electrospun nanofibers of the piezoelectric polymer, polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), by uniformly drawing the spun membranes containing cellulose nanocrystals (CNC, 2 wt%) and the Fe-doped nano ZnO (2 wt%). The hybrid nanocomposite fibers were made in double layers, with CNC/PVDF-HFP composite on one side and the Fe-doped ZnO/PVDF-HFP on the other side. This ferroelectric polymer composite exhibited maximum peak-to-peak output voltage of 12 V with a current density, 1.9 ?Acm?2, which are respectively higher by 60 and 2.3 times compared to the neat polymer fibers. The PENG is tested for its energy harvesting ability by exposing it to different environments such as ultrasound vibrations and human body movements during hand tapping, elbow movements and by attaching with the textile fabrics. While the finger tapping generated peak-to-peak output voltage of 6.5 V, elbow movements resulted in 5.5 V generation. In all sorts of movements, the nanogenerator shows good output performance indicating its compatibility with textile materials. The mechanical properties, breakdown strength and dielectric properties of the material are also in accordance with its possible applications in wearable electronic textiles. - 2019 The AuthorsThis publication is made possible by NPRP grant 6-282-2-119 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Designing carbon nanotube-based oil absorbing membranes from gamma irradiated and electrospun polystyrene nanocomposites

Carbon-based materials are outstanding candidates for oil spill clean-ups due to their superhydrophobicity, high surface area, chemical inertness, low density, recyclability, and selectivity. The current work deals with the fabrication of membrane oil absorbents based on carbon nanotube (CNT) reinforced polystyrene (PS) nanocomposites by electrospinning technique. The spun membranes are also irradiated with the gamma radiation to induce enough crosslinks and thus good polymer-filler interactions. The structural, morphological, and surface properties in addition to the oil/water separation efficiency were investigated by varying the concentration of CNT and the dose of γ-irradiation. Fabricated nanofiber membranes show superior hydrophobicity and selective oil absorption at 0.5 wt.% of CNT concentration. The best mechanical properties are also obtained at this particular concentration and at 15 KGy optimum γ-irradiation dosage. The gamma irradiated PS/0.5 wt.% CNT membrane also exhibits good antibacterial effects against the bacteria, Escherichia coli, in the form of bacterial inhibition rings around the membranes. The present study thus shows the environmental applicability of the fabricated PS/CNT membranes in treating oil-contaminated water

Sunlight-Driven Combustion Synthesis of Defective Metal Oxide Nanostructures with Enhanced Photocatalytic Activity

Synthesis of metal oxide nanostructures through combustion routes is a promising technique owing to its simplicity, rapidity, scalability, and cost-effectiveness. Herein, a sunlight-driven combustion approach is developed to synthesize pristine metal oxides and their heterostructures. Sunlight, a sustainable energy source, is used not only to initiate the combustion reaction but also to create oxygen vacancies on the metal oxide surface. ZnO nanostructures are successfully synthesized using this novel approach, and the products exhibit higher photocatalytic activity in the decomposition of methyl orange (MO) than ZnO nanostructures synthesized by the conventional methods. The higher photocatalytic activity is due to the narrower band gap, higher porosity, smaller and more uniform particle size, surface oxygen vacancies, as well as the enhanced exciton dissociation efficiency induced by the sunlight. Porous Fe3O4 nanostructures are also prepared using this environmentally benign method. Surprisingly, few-layer Bi2O3 nanosheets are successfully obtained using the sunlight-driven combustion approach. Moreover, the approach developed here is used to synthesize Bi2O3/ZnO heterostructure exhibiting a structure of few-layer Bi2O3 nanosheets decorated with ZnO nanoparticles. Bi2O3 nanosheets and Bi2O3/ZnO heterostructures synthesized by sunlight-driven combustion route exhibit higher photocatalytic activity than their counterparts synthesized by the conventional solution combustion method. This work illuminates a potential cost-effective method to synthesize defective metal oxide nanostructures at scale. Copyright - 2019 American Chemical Society.This study was supported by University Grants Commission, India, under University with Potential for Excellence (UPE) program at University of Mysore, UGC JRF (Award No. F.19-1/2013(SA-I)), and Deanship of Scientific Research (DSR) at King Fahd University of Petroleum & Minerals (KFUPM) through project no. DF181021.Scopu

Gas Sensing and Power Harvesting Polyvinylidene Fluoride Nanocomposites Containing Hybrid Nanotubes

Gas sensing properties at room temperature and energy harvesting performances are realized for the polyvinylidene fluoride (PVDF) nanocomposites containing titanium dioxide (TiO2) nanotubes grown in the presence of carbon nanotubes (CNT). While hydrothermal reaction is practiced for the development of TiO2/CNT hybrid nanotubes, spin coating is done for the nanocomposite films to be deposited on sensing electrodes. Influence of various filler concentrations and the synergistic combination of fillers on the sensing characteristics are studied by recording the response times and the stability of the results. Upon exposure to liquefied petroleum gas, the PVDF/TiO2-CNT (2.5 wt.%) gas sensor shows a sensing response of 0.45 s (400 ppm LPG), approximately nine times higher than the composite containing 2.5 wt.% of TiO2 or 2.5 wt.% CNT. The piezoelectric response of the samples is also recorded and correlated with the synergistic influence of the filler materials. The current study can stimulate a good trend in fabricating self-powered gas sensors from PVDF nanocomposites.Open Access funding provided by the Qatar National Library. This publication was made possible by NPRP Grant 6-282-2-119 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Piezoelectric properties of zinc oxide/iron oxide filled polyvinylidene fluoride nanocomposite fibers

Piezoelectric nanogenerators (PENG) with flexible and simple design have pronounced significance in fabricating sustainable devices for self-powering electronics. This study demonstrates the fabrication of electrospun nanocomposite fibers from polyvinylidene fluoride (PVDF) filled zinc oxide (ZnO)/iron oxide (FeO) nanomaterials. The nanocomposite fiber based flexible PENG shows piezoelectric output voltage of 5.9 V when 3 wt% of ZnO/FeO hybrid nanomaterial is introduced, which is 29.5 times higher than the neat PVDF. No apparent decline in output voltage is observed for almost 2000's attributed to the outstanding durability. This higher piezoelectric output performance is correlated with the ?-phase transformation studies from the Fourier transformation infrared spectroscopy and the crystallinity studies from the differential scanning calorimetry. Both these studies show respective enhancement of 3.79 and 2.16% in the ?-phase crystallinity values of PVDF-ZnO/FeO 3 wt% composite. Higher dielectric constant value obtained for the same composite (three times higher than the neat PVDF) confirms the increased energy storage efficiency as well. Thus the proposed soft and flexible PENG is a promising mechanical energy harvester, and its good dielectric properties reveals the ability to use this material as good power sources for wearable and flexible electronic devices.Open access funding provided by the Qatar National Library. This publication was made possible by UREP Grant 24-142-1-032 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Effect of anions on the structural, morphological and dielectric properties of hydrothermally synthesized hydroxyapatite nanoparticles

Synthetic nano hydroxyapatites (HA) have been considered as potential biomaterials for bone tissue engineering applications because of its excellent biological properties. The present work deals with the synthesis of HA nanoparticles from different anion source materials via autoclave assisted hydrothermal method. All the prepared HA nanoparticles were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectra, field emission scanning electron microscopy, energy dispersive spectra and high resolution transmission electron microscopy. The XRD patterns reveal the pure and hexagonal phase structure with smaller crystallite size for HA obtained from various calcium salt precursors. HA particles prepared from nitrate precursors show spherical morphology with 32 nm grain size whereas those derived from the acetate, chloride and egg shell precursors respectively show needle-like, irregular and oval morphology. The effect of different anions on the dielectric properties and alternating conductivity of HA is investigated, as a polarized surface can trigger biological reactions. For the particles obtained from nitrate, acetate, chloride and egg shell precursors respectively give dielectric constant (εʹ) values of 9.96, 13.22, 9.92 and 10.86 at 5 MHz. The εʹ and dielectric loss (εʹʹ) values for the HA nanoparticles decrease with increase in the applied frequency as well. The alternating current conductivity values confirm that the as-synthesized HA samples exhibit insulating behavior. In short this article provides the various applicability of HA particles in optoelectronics and drug delivery.Open access funding provided by the Qatar National LibraryScopu

Core-shell nanofibers of polyvinylidene fluoride-based nanocomposites as piezoelectric nanogenerators

Flexible piezoelectric nanogenerators (PENG) are widely applied to harvest sustainable energy from multiple energy sources. The rational and simple design of PENG have great potential in soft electronics. Here we design a highly flexible PENG using the polyvinylidene fluoride (PVDF) and its copolymer, polyvinylidene hexafluoropropylene (PVDF-HFP) with two nanoarchitectures of semiconducting metal oxides, TiO2 and ZnO. The nanotubes of TiO2 and nanoflowers of ZnO are embedded in these different polymeric media by solvent mixing, and new fiber mats are generated by coaxial electrospinning technique. This process aligns the dipoles of polymers and nanomaterials, which is normally a pre-requisite for higher piezo potential. With excellent mechanical strength and flexibility, the tailored lightweight fiber mats are capable of producing good output voltage (a maximum of 14 V) during different mechanical vibrations at various frequencies and in response to human motions. The hybrid nanocomposite PENG is durable and inexpensive and has possible applications in wearable electronics.This research was funded by Qatar National Research Fund grant number UREP24-142-1-032. The APC was funded by UREP24-142-1-032. The statements made herein are solely the responsibility of the authors. The SEM, TEM and EDS were accomplished in the Central Laboratories Unit, Qatar University.Scopu

Flexible pressure sensor based on PVDF nanocomposites containing reduced graphene oxide-titania hybrid nanolayers

A novel flexible nanocomposite pressure sensor with a tensile strength of about 47 MPa is fabricated in this work. Nanolayers of titanium dioxide (titania nanolayers, TNL) synthesized by hydrothermal method are used to reinforce the polyvinylidene fluoride (PVDF) by simple solution mixing. A hybrid composite is prepared by incorporating the TNL (2.5 wt %) with reduced graphene oxide (rGO) (2.5 wt %) synthesized by improved graphene oxide synthesis to form a PVDF/rGO-TNL composite. A comparison between PVDF, PVDF/rGO (5 wt %), PVDF/TNL (5 wt %) and PVDF/rGO-TNL (total additives 5 wt %) samples are analyzed for their sensing, thermal and dielectric characteristics. The new shape of additives (with sharp morphology), good interaction and well distributed hybrid additives in the matrix increased the sensitivity by 333.46% at 5 kPa, 200.7% at 10.7 kPa and 246.7% at 17.6 kPa compared to the individual PVDF composite of TNL, confirming its possible application in fabricating low cost and light weight pressure sensing devices and electronic devices with reduced quantity of metal oxides. Increase in the β crystallinity percentage and removal of α phase for PVDF was detected for the hybrid composite and linked to the improvement in the mechanical properties. Tensile strength for the hybrid composite (46.91 MPa) was 115% higher than that of the neat polymer matrix. Improvement in the wettability and less roughness in the hybrid composites were observed, which can prevent fouling, a major disadvantage in many sensor applications.Scopu

Progress of Advanced Nanomaterials in the Non-Enzymatic Electrochemical Sensing of Glucose and H2O2

Non-enzymatic sensing has been in the research limelight, and most sensors based on nanomaterials are designed to detect single analytes. The simultaneous detection of analytes that together exist in biological organisms necessitates the development of effective and efficient non-enzymatic electrodes in sensing. In this regard, the development of sensing elements for detecting glucose and hydrogen peroxide (H2O2) is significant. Non-enzymatic sensing is more economical and has a longer lifetime than enzymatic electrochemical sensing, but it has several drawbacks, such as high working potential, slow electrode kinetics, poisoning from intermediate species and weak sensing parameters. We comprehensively review the recent developments in non-enzymatic glucose and H2O2 (NEGH) sensing by focusing mainly on the sensing performance, electro catalytic mechanism, morphology and design of electrode materials. Various types of nanomaterials with metal/metal oxides and hybrid metallic nanocomposites are discussed. A comparison of glucose and H2O2 sensing parameters using the same electrode materials is outlined to predict the efficient sensing performance of advanced nanomaterials. Recent innovative approaches to improve the NEGH sensitivity, selectivity and stability in real-time applications are critically discussed, which have not been sufficiently addressed in the previous reviews. Finally, the challenges, future trends, and prospects associated with advanced nanomaterials for NEGH sensing are considered. We believe this article will help to understand the selection of advanced materials for dual/multi non-enzymatic sensing issues and will also be beneficial for researchers to make breakthrough progress in the area of non-enzymatic sensing of dual/multi biomolecules.Scopu

Multifunctional Oil Absorption with Macroporous Polystyrene Fibers Incorporating Silver-Doped ZnO

Hydrophobic microporous polystyrene (PS) fibers are fabricated by a solvent-induced phase-separation-assisted electrospinning method. Zinc oxide (ZnO) and silver-doped zinc oxide (Ag-ZnO) nanomaterials with variable morphologies are added to the PS fibers, to investigate the influence of multifunctional nanofiller addition on the porosity and consequent oil-adsorbing properties for different oil types. The doping of silver as well as the uniformity in particle distribution are confirmed by scanning electron microscopy and the energy-dispersive spectral analyses. The porosity of the fibers and their crystallinity effect depend on the hydrophobicity and surface properties of these microporous nanofilled fibers. Ag-ZnO, specifically in 2 wt %, enhanced the pore size and distribution in PS porous fibers, thereby enhancing the oil-adsorbing property and its hydrophobicity. In-depth analysis of the oil adsorption mechanism is done for the fibers, both qualitatively and quantitatively, to demonstrate its correlation with the structural integrity of the fibers. The PS/2Ag-ZnO composite also exhibits the highest antibacterial performance against Staphylococcus aureus, a general indication of antibiological fouling properties of these oil-separating films. The antifouling/antibacterial activity of the nanoparticles and high oil sorption capacity of the highly porous PS composites show great potential for use in water-treatment-related applications.This publication was made possible by NPRP grant 10-0127-170269 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The SEM, TEM, and EDS analyses were accomplished in the Central Laboratories Unit, Qatar University. A.A.E. acknowledges Qatar University for the support granted through Graduate Research Assistantship Program (GRA).Scopu