In
this work, we discovered a very efficient method of crystallization
of thermally evaporated rubrene, resulting in ultrathin, large-area,
fully connected, and highly crystalline thin films of this organic
semiconductor with a grain size of up to 500 μm and charge carrier
mobility of up to 3.5 cm2 V–1 s–1. We found that it is critical to use a 5 nm-thick organic underlayer
on which a thin film of amorphous rubrene is evaporated and then annealed
to dramatically influence the ability of rubrene to crystallize. The
underlayer property that controls this influence is the glass transition
temperature. By experimenting with different underlayers with glass
transition temperatures varying over 120 °C, we identified the
molecules leading to the best crystallinity of rubrene films and explained
why values both above and below the optimum result in poor crystallinity.
We discuss the formation of different crystalline morphologies of
rubrene produced by this method and show that field-effect transistors
made with films of a single-domain platelet morphology, achieved through
the aid of the optimal underlayer, outperform their spherulite counterparts
with a nearly four times higher charge carrier mobility. This large-area
crystallization technique overcomes the fabrication bottleneck of
high-mobility rubrene thin film transistors and other related devices
and, given its scalability and patternability, may lead to practical
technologies compatible with large-area flexible electronics.
In order to achieve the treatment of antibiotic pollutants by solid waste, and for the purpose of improving the selectivity while enhancing the photocatalytic efficiency, this work used fly-ash cenospheres (FC) (obtained from coal fly ash, a typical solid waste) as the carrier, o-phenylenediamine (OPD) as the imprinted functional monomer, a conductive polymerizable monomer, enrofloxacin hydrochloride (EH) as the molecular template and TiO 2 @magnetic floating fly-ash cenospheres (TMFFC) as the matrix material. A magnetic conductive imprinted photocatalyst (MCIP) was synthesized via surface imprinting technology and a one-pot photo-induced method. The as-prepared MCIP was extensively characterized by SEM, N 2 adsorption-desorption analysis with the Brunauer-Emmett-Teller (BET) method, FT-IR, elemental analysis, TGA, UV-vis and vibrating sample magnetometry (VSM). The results showed that the MCIP possessed a hollow spherical structure, floating and magnetic separation properties (Ms = 9.16 emu g 21 ), the conductive polymer (POPD) was successfully introduced into the surface-imprinted layer, and the electrical conductivity of MCIP was 0.359 us cm 21 . The photodegradation rate, pseudo-first-order constant and coefficient of selection were calculated in detail, and all these data indicated that the MCIP not only had higher photocatalytic efficiency for the degradation of EH compared with other photocatalysts (such as the traditional surface-imprinted photocatalysts and TMFFC), but also possessed better selection for adsorption and photodegradation of EH in single/binary antibiotic solution. The mechanism of selective photodegradation of EH was also investigated.
The low pH of magnesium potassium phosphate (MKPC) has raised concerns over its capability to protect reinforcing steel. The passivation of mild steel in MKPC pore solutions was investigated in this study via electrochemical measurements, XPS and Raman spectroscopy. Results show that the passivity of mild steel in MKPC was comparable or even better than that in Portland cement. Although the passivity was dominated by the pH of MKPC, 2 it also increases with increasing magnesium-to-phosphate (M/P) ratios. The formation of iron phosphate in the low pH MKPC (such as M/P 7) also made additional contributions to the passivity of steel.
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