Functionalized graphene quantum dot (GQD) based materials play an important role in the development of high-performance, low-cost, large-area optoelectronic devices. The progress, however, is impeded by the poor understanding of the physical mechanism for GQDs in these devices. In this paper, chlorine doped GQD (Cl-GQD) based photovoltaic photodetectors have been fabricated using a solution process, and it was found that the presence of Cl-GQDs can significantly enhance the performance of the device. The improved performance of Cl-GQD based devices has been investigated by systematically studying the structural, morphological, optical, electrical, electrochemical and photoelectrical properties. The important photovoltaic detectors parameters such as the saturation current densities (J 0 ), barrier heights (F b ), built-in potentials (V bi ), carrier concentrations (N) and depletion layer widths (W d ) have been calculated and discussed by studying the I-V and C-V characteristics under different illuminations. The frequency dependent capacitance and conductance have also been discussed. The results provide guidance for developing high-performance graphene based optoelectronic devices.

Micrometer–nanometer hydrophobic titania–fluoroalkylsilane composite coatings were prepared on substrates based on liquid‐phase deposition. Coatings and crystallization forms were characterized with instruments of surface analyses. Experimental facilities of pool boiling were established to evaluate heat and mass transfer on coated surfaces in deionized water and saturated calcium carbonate solution. Obvious pool boiling enhancement was observed on thinner microscale–nanoscale hydrophobic titania–fluoroalkylsilane composite films at higher heat fluxes compared to that on thicker titania–fluoroalkylsilane coatings or on titania coatings and stainless steel surfaces. Lower fouling resistance was obtained on titania–fluoroalkylsilane coatings in pool boiling of saturated calcium carbonate solution and crystal form was aragonite, which was different from calcite on titania coatings. Results of inhibition of fouling and enhancement of heat transfer on titania–fluoroalkylsilane coatings were contributed to special surface microscale–nanoscale structure and material wettability. Asymptotic model was used to fit experimental data of fouling resistance, and reasonable agreement was obtained. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2662–2678, 2013

Corrosion and scaling phenomena often appear simultaneously and act synergistically in geothermal water system. We prepared the nano-ZrO2–TiO2 composite coatings on the AISI type 304 stainless steel with the chemical liquid phase deposition method. Surface morphology, crystal form, and chemical elements of the coatings were investigated with field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy analyzer, X-ray diffraction, and thermal gravimetric/differential thermal analyses instruments, respectively. Corrosion behaviors and scale properties were tested by potentiodynamic polarization and electrochemical impedance spectroscopy measurements in the simulated geothermal water at 50 °C. The results reveal that the anticorrosion performance of the ZrO2–TiO2 composite coating is markedly improved compared to the austenitic stainless steels. A pitting corrosion and scale deposition mechanism was proposed for the ZrO2–TiO2 composite coating in the simulated geothermal water. These findings have potential implication for the protection of the austenitic stainless steel against the geothermal water corrosion.

Fouling deposition and localized corrosion on the heat‐transfer surfaces of the stainless steel equipments often simultaneously exist, which can introduce additional thermal resistance to heat‐transfer and damage heat‐transfer surfaces. It is a good anticorrosion way to coat a barrier layer of certain materials on the metal surface. In this article, the TiO2 coatings with nanoscale thicknesses were obtained by liquid‐phase deposition method on the substrates of AISI304 stainless steel (ASS). The coating thickness, surface roughness, surface morphology, crystal phase, and chemical element were characterized with the film thickness measuring instrument, roughmeter, atomic force microscopy, field emission scanning electron microscopy, X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy analyzer, respectively. Corrosion behavior of the TiO2 coatings was evaluated by potentiodynamic polarization, cyclic voltammograms scanning, and electrochemical impedance spectroscopy tests with the mixed corrosion solution composed of 3.5 wt. % NaCl and 0.05 M NaOH. It is shown that the TiO2 coating is composed of the nanoparticles with smooth, crack‐free, dense, and uniform surface topography; the roughness of coating surface increases slightly compared with that of the polished ASS substrate. The anatase‐phase TiO2 coatings are obtained when sintering temperature being varied from 573.15 to 923.15 K and exhibit better anticorrosion behavior compared with ASS surfaces. The corrosion current density decreases and the polarization resistance increases with the increase of the coating thickness. The corrosion resistance of the TiO2 coatings deteriorates with the increase of the corrosion time. The capacitance and the resistance of the corrosion product layer between the interface of the ASS substrate and the TiO2 coating are found after the corrosion time of 240 h. A corrosion model was introduced, and a possible new explanation on the anticorrosion mechanisms of the TiO2 coating was also analyzed. The corrosion mechanism of the TiO2 coating might comply with the multistage corrosion process. © 2011 American Institute of Chemical Engineers AIChE J, 58: 1907–1920, 2012