Interfacial bonding in a CdS/PVA nanocomposite: A Raman scattering study

Rudko, G. Yu.; Kovalchuk, Andrii; Fediv, V. I.; Chen, Weimin; Buyanova, Irina

doi:10.1016/j.jcis.2015.04.020

Cited by 21 publications

(18 citation statements)

References 23 publications

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“…The OH peak from 15 kV nanofibers shifted from 3175 to 3155 cm −1 , and the OH peak of 45 kV nanofibers shifted from 3165 to 3150 cm −1 . These trends indicate hydrogen bonding between TiO 2 nanoparticles and PVA OH groups …”

Section: Resultsmentioning

confidence: 92%

“…Compared to 15 kV nanofibers, 45 kV nanofibers showed strong Raman peaks at 1072 to 1095 cm −1 , which are assigned to saturated secondary alcohols . These strong CO Raman peaks at 1072 and 1095 cm −1 relate to amorphous polymer.…”

Section: Resultsmentioning

confidence: 94%

“…Amorphous TiO 2 formed along the 45 kV nanofibers, as noted by the low intensity Raman peaks between 100 and 800 cm −1 ( Figure ). Incomplete hydrolysis of TTIP as shown by the CH and OH bending peak at 1440 cm −1 as well as strong CH 2  peak at 2880–2980 cm −1 indicates amorphous TiO 2 . Residual TTIP alkoxy groups stem from incomplete hydrolysis and behave as structural impurities that hinder TiO 2 crystallization .…”

Section: Resultsmentioning

confidence: 99%

“…Raman spectra were collected using the 532 nm laser at 150 mW power, 10X objective lens, 20 scans, and 1 s exposure time. Peaks were normalized by the 2910 cm −1 peak which represent CH stretching of multiple CH 2  groups …”

Section: Methodsmentioning

confidence: 99%

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Titanium Oxide Sol–Gel Induced Wrinkling of Electrospun Nanofibers

Park

Ford

2018

Macro Chemistry & Physics

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TiO2 sol–gel reaction induces nanowrinkling along the surface of electrospun poly(vinyl alcohol) (PVA) nanofibers. Nanowrinkling along nanofibers is influenced by electrospinning voltage, degree of nanofiber crosslinking, and the repetitive immersion of nanofibers in TiO2 precursors. Crosslinked nanofibers are dipped in alternating solutions of titanium tetraisopropoxide (TTIP) and water for up to five cycles. Interestingly, nanowrinkles only form along nanofibers that are spun at 45 kV and treated with three or more cycles of sol–gel precursor. Spectroscopy reveals that more PVA hydroxyl groups populate the nanofiber surface when electrospinning occurs at 45 kV than at 15 kV. In turn, surface PVA hydroxyl groups appear to nucleate TiO2 growth. Scanning probe phase micrographs confirm modulus differences between the attached TiO2 particles and PVA's surface. Those moduli differences result in wrinkling, as TTIP‐treated nanofibers undergo repetitive cycles of water swelling and isopropanol deswelling.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Titanium Oxide Sol–Gel Induced Wrinkling of Electrospun Nanofibers

Park

Ford

2018

Macro Chemistry & Physics

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“…A more likely reason for the photoenhancement could be an improved crystallinity of the polymer and the NC/polymer interface, as suggested in the DPL photoenhancement study [32] of CdSe/PVA NCs similar to those in our work. In particular, it was suggested that in the NC/PVA composite, the individual functional groups of PVA as well as the fragments of the partially-broken polymer chains can passivate under-coordinated surface atoms of the NCs with the formation of chemical complexes between the -C=O group of the PVA matrix and the Cd 2+ ions on the NC surface [32,53]. However, if the specific bonding were dominant and common to all NC/polymer samples studied in this work, we would observe more similarity in the photoinduced behavior of different in situ and ex situ embedded NCs in the same polymers, on the one hand, and less similarity between similar NCs embedded in different polymers.…”

Section: Excitation Power Dependence Of the Pl Spectra Of Ncsmentioning

confidence: 99%

Photoinduced Enhancement of Photoluminescence of Colloidal II-VI Nanocrystals in Polymer Matrices

et al. 2020

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The environment strongly affects both the fundamental physical properties of semiconductor nanocrystals (NCs) and their functionality. Embedding NCs in polymer matrices is an efficient way to create a desirable NC environment needed for tailoring the NC properties and protecting NCs from adverse environmental factors. Luminescent NCs in optically transparent polymers have been investigated due to their perspective applications in photonics and bio-imaging. Here, we report on the manifestations of photo-induced enhancement of photoluminescence (PL) of aqueous colloidal NCs embedded in water-soluble polymers. Based on the comparison of results obtained on bare and core/shell NCs, NCs of different compounds (CdSe, CdTe, ZnO) as well as different embedding polymers, we conclude on the most probable mechanism of the photoenhancement for these sorts of systems. Contrary to photoenhancement observed earlier as a result of surface photocorrosion, we do not observe any change in peak position and width of the excitonic PL. Therefore, we suggest that the saturation of trap states by accumulated photo-excited charges plays a key role in the observed enhancement of the radiative recombination. This suggestion is supported by the unique temperature dependence of the trap PL band as well as by power-dependent PL measurement.

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Modulating ZnO Growth Structures for Maximum Power Output of Hybrid Piezo/Triboelectric Nanogenerator

Lim

Koay

Zhao

et al. 2022

Adv Funct Materials

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Hybrid piezo/triboelectric nanogenerators (H-P/TENGs) are developed to compensate the drawbacks of a single nanogenerator by synergizing high triboelectric output voltage and piezoelectric output current in continuous contact-separation cycles. In particular, piezoelectric zinc oxide (ZnO) has been widely used due to its excellent orientation along the c-axis and tunable growth structures. Herein, various growth structures of ZnO, unoriented, oriented, and hierarchical structures, are incorporated in H-P/TENGs, enhancing their power densities from 6 to 17 times. Particularly, oriented ZnO nanorod/ PVA (ZnR) achieves a maximum power density of 15.9 W m −2 (≈17-fold increment compared to pristine PVA). The highly oriented ZnO growth along the c-axis enables large deformation upon a vertical compression, subsequently generating a large piezoelectric polarization. Moreover, the enhancement mechanism via piezoelectric polarization is elucidated using a modified overlapped electron cloud model supported with Kelvin probe force microscopy measurements. The polarization of ZnO nanocomposites enlarges the difference in the highest electron energies (ΔE) between the two triboelectric layers, driving more electrons to transfer during contact electrification, thereby enriching their surface charge densities. This study highlights the significance of growth structure control in maximizing the piezoelectric responses of ZnO, consequently improving the output performances of H-P/TENGs.

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Interfacial bonding in a CdS/PVA nanocomposite: A Raman scattering study

Cited by 21 publications

References 23 publications

Titanium Oxide Sol–Gel Induced Wrinkling of Electrospun Nanofibers

Titanium Oxide Sol–Gel Induced Wrinkling of Electrospun Nanofibers

Photoinduced Enhancement of Photoluminescence of Colloidal II-VI Nanocrystals in Polymer Matrices

Modulating ZnO Growth Structures for Maximum Power Output of Hybrid Piezo/Triboelectric Nanogenerator

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