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Polyaniline (PANI)/Cu–ZnS composites with porous microspheres are prepared by a hydrothermal and in situ polymerization method. The structural, optical, and morphological properties are characterized by X-ray powder diffraction, FTIR, UV-vis, scanning electron microscope, transmission electron microscope. The XRD results confirmed that the PANI/Cu–ZnS composite is formed. The morphological analyses exhibited that the PANI/Cu–ZnS composite comprises the porous microspherical structures. The emission peaks obtained in photoluminescence spectra confirm the presence of surface defects in the prepared composite. The UV-DRS study shows that the bandgap of the samples is found to decrease for the PANI/Cu–ZnS composite compared to the pure Cu–ZnS sample. The calculated band gap (Eg) value of PANI/Cu–ZnS composite is 2.47 eV. Furthermore, the fabricated gas sensor based on PANI/Cu–ZnS can perform at room temperature and exhibits good gas sensing performance toward CO2 gas. In particular, PANI/Cu–ZnS sensor shows good response (31 s) and recovery time (23 s) upon exposure to CO2 gas. The p/n heterojunction, surface defects, and porous nature of the PANI/Cu–ZnS composite microsphere enhanced sensor performance. Other information Published in: RSC Advances License: http://creativecommons.org/licenses/by-nc/3.0 See article on publisher's website: http://dx.doi.org/10.1039/d0ra04991c

Over the past decade, piezoelectric nanogenerator have attracted much attention to harvest mechanical energy from abundant resources in nature. Here, the ZnS microspheres is prepared by hydrothermal method and core-shell structured PANI/ZnS microspheres are synthesized by in situ polymerization method and then used as filler for the preparation of flexible [P(VDF-HFP)] based piezoelectric nanogenerator. The flexible P(VDF-HFP)/PANI-ZnS piezoelectric nanogenerator is prepared by Electrospinning technique. The core-shell PANI/ZnS composite improves the content of electroactive phase in [P(VDF-HFP)] and significantly improves the interfacial polarization between the PANI/ZnS particles and polymer matrix. Among all the samples, [P(VDF-HFP)]/2 wt% PANI-ZnS composite nanofibers exhibited the high piezoelectric peak-to-peak output voltage of 3 V compared with the neat [P(VDF-HFP)] (~ 120 mV). In addition, the high dielectric constant is observed for the [P(VDF-HFP)]/2 wt% PANI-ZnS composite nanofibers. These results implies that the fabricated flexible and efficient piezoelectric nanogenerator can be utilized for energy harvesting system.Other Information Published in: Journal of Materials Science: Materials in Electronics License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s10854-021-05352-4

Metals, including austenitic steels and alloys, have been extensively applied in industrial and engineering applications. Passive films on metal surfaces are very important for corrosion protection. However, localized attack, such as passive film breakdown and the initiation of pits, is found upon exposure of such metals to aggressive ion-containing environments, leading to material failure and prominent adverse economic and safety concerns. For several decades, the mechanism of passivity breakdown and pit nucleation during pitting corrosion has been widely studied. The present article provides a detailed review of passive film breakdown on metal surfaces and the effects of complicated conditions, such as chloride- and sulfide-ion concentrations, temperature, and solution pH, on passivity breakdown. The possible mechanism for passivity breakdown is reviewed and discussed. The composition, structure, and electronic properties of passive layers are of conclusive importance to understand the leading corrosion mechanism, and they have been investigated with different techniques. Furthermore, we aim to present the structure, chemical composition, and electronic properties of passive films on metal surfaces by using X-ray photoelectron spectroscopy and energy-dispersive spectroscopy. Additionally, the surface morphology of passive films is analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques. Finally, the effect of chloride- and sulfide-ion concentrations, pH, and temperature on passivity breakdown is discussed in detail.Other Information Published in: Emergent Materials License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s42247-021-00194-6

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.Other Information Published in: SN Applied Sciences License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s42452-019-1807-3

In this work, stable hydrophobic nanocomposites are made from electrospun fibers of polystyrene (PS) containing a hybrid filler combination of (i) hexagonal boron nitride (hBN) and (ii) cobalt oxide (Co3O4) nanomaterials. Good synergistic interaction is observed between the nanomaterials, since the growth of Co3O4 was carried out in presence of white graphene nanosheets. Filler synergy modifies the PS surfaces, by enhancing the filler-polymer interfacial interactions and provides good tensile strength. The hydrophobic films are gamma irradiated to improve crosslinking within the polymer nanocomposites. Since gamma irradiation enhances the surface roughness, its hydrophobicity/oleophilicity increases much and the final nanofibers show good oil-water separation efficiency. The nanofibers act as sponge clothing to skim the oil from a mixture of oil and water. Durability of the fibers in hot water and in presence of ultrasonic waves is also tested and good response is achieved. Contact angle studies are performed to investigate the surface properties and to check the influence of gamma irradiation on the surface wettability. The gamma-irradiated PS nanocomposite fiber shows a contact angle of 152&deg, &plusmn, 2&deg, compared to the 140&deg, 1&deg, of the neat PS fiber, evidencing the superhydrophobicity. Both the effects of crosslink density enhancement and hybrid filler distribution make the composite fibers stronger in oil absorption application even at higher operation temperatures. The fibers are reported to be robust and durable, in addition.