Macroporous Nb2O5(MP‐Nb2O5) has been synthesized using dispersed polystyrene microspheres (PS) as template followed by annealing in air. The structural characterization showed that the diameters of the macropores are around 200 nm and the average particle size of the composition is 20–50 nm. XPS revealed the presence of low valence Nb4+and oxygen vacancies on the surface of the resulting product introduced during the pyrolysis of PS. Such a unique combination of macroporous nanostructure and tetravalent niobium ions enables the electrode with superior lithium ion insertion properties, such as high specific capacity (≈190 mA h g−1at 0.5C) and rate capability. Even at a current density of 1.6 A g−1, an average capacity of 129.2 mA h g−1can still be obtained. These findings demonstrate MP‐Nb2O5is a promising candidate for high‐rate lithium ion storage applications.
Atmospheric pressure plasma functionalization of polystyrene
Atmospheric pressure plasma jets (APPJs) are used to improve the adhesive and hydrophilic properties of commodity hydrocarbon polymers such as polypropylene, polyethylene, and polystyrene (PS). These improvements largely result from adding oxygen functional groups to the surface. PS functionalization is of interest to produce high value biocompatible well-plates and dishes, which require precise control over surface properties. In this paper, we discuss results from a computational investigation of APPJ functionalization of PS surfaces using He/O 2 /H 2 O gas mixtures. A newly developed surface reaction mechanism for functionalization of PS upon exposure to these plasmas is discussed. A global plasma model operated in plug-flow mode was used to predict plasma-produced species fluxes onto the PS surface. A surface site balance model was used to predict oxygen-functionalization of the PS following exposure to the plasma and ambient air. We found that O-occupancy on the surface strongly correlates with the O-atom flux to the PS, with alcohol groups and cross-linked products making the largest contributors to total oxygen fraction. Free radical sites, such as alkoxy and peroxy, are quickly consumed in the post-plasma exposure to air through passivation and cross-linking. O-atom fluences approaching 10 17 cm −2 saturate the O-occupancy on the PS surface, creating functionality that is not particularly sensitive to moderate changes in operating conditions.
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- PAR ID:
- 10339369
- Date Published:
- Journal Name:
- Journal of Vacuum Science & Technology A
- Volume:
- 40
- Issue:
- 4
- ISSN:
- 0734-2101
- Page Range / eLocation ID:
- 043001
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1116/6.0001850
