Minlin Yang

Nanowires of α- and β-Bi2O3: phase-selective synthesis and application in photocatalysis

This paper is focused on the first selective synthesis of α-and β-Bi2O3 nanowires by an oxidative metal vapour transport deposition technique. The nanowires growth conditions have been systematically investigated, providing insights into the mechanism of nanowires formation. We make a critical comparison of photocatalytic properties of the α- and β-Bi2O3 nanowires by the photo-degradation of Orange G under visible light. The β-Bi2O3 nanowires have shown the highest photo-catalytic activity under visible light of all the tested samples of Degussa TiO2 P25 and α-/β-Bi2O3 nanowires, which can be interpreted by the narrowest band gap of the β-Bi2O3 nanowires for the most effective harvest of the visible light as well as their smallest size for the most facile transfer of photo-excited electrons and the consequent most effective electron-hole separation.

Electrodeposition of manganese dioxide film on activated carbon paper and its application in supercapacitors with high rate capability

In this research magnesium dioxide (MnO2) is electrodeposited over activated carbon paper (ACP) to form a composited MnO2/ACP material. The as-prepared MnO2/ACP shows excellent capacitance performance with a high specific capacitance of 485.4 F g−1 calculated from a discharge curve with current density 2.0 A g−1, owing to its enlarged specific surface area and improved electronic conductivity. Moreover, the MnO2/ACP possesses remarkable rate capability due to the easy access of electrolytic ions, leading to complete utilization of MnO2 active material for supercapacitors. To summarize, the electrodeposition of MnO2 thin film on activated carbon paper is reported for the first time, and the composited MnO2/ACP is a promising electrode material for building up efficient supercapacitors.

Chitosan as green kinetic inhibitors for gas hydrate formation

The kinetic inhibiting effect of a number of chitosans on hydrate formation was investigated using methane and methane/ethane gas mixtures. The results indicated that chitosan was a good kinetic inhibitor. The induction time of gas hydrate formation evidently increased with the degree of deacetylation (DD), however, when DD was higher than 80%, the effect of DD on the induction time was negligible. Moreover, it was found that the molecular weight (MW) of chitosan and the addition of polyethylene oxide (PEO) had little effect on the induction time. The optimal concentration of chitosan was found to be 0.6 wt%. Finally, the mechanisms of the kinetic inhibitor on the hydrate formation were discussed.

Effects of the Random Distributions on the Laminar Flow and Heat Transfer in a Quasi-Counter Flow Parallel-Plate Membrane Channel

ABSTRACT An internally cooled parallel-plate membrane contactor has been employed for liquid desiccant air dehumidification. The contactor is comprised of a series of quasi-counter flow parallel-plate membrane channels (QCPMC). The processing air and the liquid desiccant (solution) streams are separated by the membranes. Cooling tubes are installed in the solution channel to take away the absorption heat. The laminar flow and heat transfer in the QCPMC with the cooling tubes in the solution side (QCPMCC) are studied based on a unit cell containing the sandwiched domain outside the cooling tubes between two neighboring membranes. This paper is focused on the effects of the random distributions in the height direction on the transport phenomena in the QCPMCC. The governing equations of the momentum and thermal transports are built up together with a uniform wall temperature boundary condition. The product of the mean friction factor and Reynolds number and the mean Nusselt number are then calculated. Effects of the various random distributions in the height direction on the product of the mean friction factor and Reynolds number and the mean Nusselt number are analyzed. Compared to the regular arrangement, the mean Nusselt number for the random distribution is larger than that for the regular one when the Reynolds number is less than 68.5. However when the Reynolds number is larger than 68.5, the mean Nusselt number for the random distribution is smaller than that for the regular one.