Heyong Huang

Application of the soluble salt-assisted route to scalable synthesis of ZnO nanopowder with repeated photocatalytic activity

In this paper, the soluble salt-assisted route has been extended to the low-cost and scalable preparation of ZnO nanostructures via the simple oxidation of Zn-Na2SO4 mixture followed by washing with water. The as-prepared ZnO nanopowders are of nanoscaled size, hexagonal phase, and pure, without being stained by Na2SO4. Their optical band gap is 3.22 eV, exhibiting a red-shift of 0.15 eV in comparison with pure ZnO bulk, and their optical absorbance is strong in the region of 200-400 nm, suggesting their full utilization of most of the UV light in sunlight. The product shows evident photocatalytic activity in degradation of RhB under solar light irradiation, and then its solar light degradation efficiency is close to that under UV irradiation, indicating that there is a possibility of practical application. More importantly, the obtained ZnO nanoparticles, because of the quick precipitation by themselves in solution with no stirring, could be easily recycled without any accessorial means such as high-speed centrifuge. The low-cost and scalable preparation, high photocatalytic activity, and convenient recycling of this ZnO nanomaterial gives it potential in purifying waste water. Hence the interesting results in this study indicate the wide range of the soluble salt-assisted route for the industrial preparation of many other advanced nanomaterials.

Selective photoreduction of nitrobenzene to aniline on TiO2 nanoparticles modified with amino acid

The photoreduction of nitrobenzene (NB) on TiO(2) nanoparticles modified with asparagine (Asp), serine (Ser), phenylalanine (Phe) and tyrosine (Tyr), which were found to bind to TiO(2) via carboxyl group, have been investigated under high-pressure mercury irradiation. Modification of TiO(2) with Asp, Ser and Phe resulted in enhanced photocatalytic degradation rate of NB and high selective activity to aniline (AN) compared to using bare TiO(2). Furthermore, NB degradation followed a reductive approach over Asp, Ser, Phe-modified TiO(2) whether in additional of methanol or not. The result indicates that modification of TiO(2) with electron-donating groups is an effective way to enhance photoreduction of nitroaromatic compounds.

A soluble salt-assisted facile synthetic route to semiconducting GaN nanoparticles

By using the soluble salt as the dispersant, a facile synthetic route has been developed to prepare GaN nanoparticle powders on a large scale and in a high yield of 95.8% through the direct nitridation of Ga–Na2SO4 mixture at 700 °C and followed by washing with water. This preparation method is also applicable to some other low-melting-point-metal oxides. The simple preparation procedure and the range of potential applications of the products made this work both scientifically and technologically interesting.

Visible light photocatalytic reduction of Cr(VI) on Ag3PO4 nanoparticles

AbstractAg3PO4 nanoparticles of ∼300 nm were synthesized by an ion-exchange reaction between AgNO3 and (NH4)2HPO4 at ambient condition. X-ray powder diffraction, scanning electron microscopy, UV−Vis diffuse reflectance spectroscopy were employed to investigate the phase structure, morphology, and optical property of the Ag3PO4 nanoparticles. Nearly 80% of Cr(VI) ions was removed after visible-light irradiation in Ag3PO4 suspension, the excellent photocatalytic reduction performance due to the high separation efficiency of electron and hole pairs. In addition, the possible photoreduction mechanism of Cr(VI) in Ag3PO4 suspension was discussed. The system of Ag3PO4 may provide an alternative way for the efficient removal of Cr(VI) under visible-light irradiation.

Studies on the Photoinduced Interaction between Zn(II) Porphyrin and Colloidal TiO2

The interaction of Zn(II) porphyrin (ZnPP) with colloidal TiO2 was studied by absorption and fluorescence spectroscopy. The fluorescence emission of ZnPP was quenched by colloidal TiO2 upon excitation of its absorption band. The quenching rate constant () is M−1 s−1. These data indicate that there is an interaction between ZnPP and colloidal TiO2 nanoparticle surface. The quenching mechanism is discussed on the basis of the quenching rate constant as well as the reduction potential of the colloidal TiO2. And the mechanism of electron transfer has been confirmed by the calculation of free energy change by applying Rehm-Weller equation as well as energy level diagram.

Preparation and Characterization TiO2 Microspheres for the LiquidChromatography Stationary Phase

TiO2 microspheres with a uniform particle size distribution were synthesized by hydrothermal method. After being sintered, the titania microspheres that are obtained have an average diameter of 5 μm, a surface area of 383.5 m2/g, an average pore volume of 0.25 cm3/g, and an average pore diameter of 35.9 nm. Normal phase chromatography was separated the mixture of benzene, nitrobenzene and nitro-anisole, three substances were separated well on the titania column. The microspheres possess enough rigidity to withstand high packing pressure and are very useful as a new kind of chromatographic packing material for high performance liquid chromatography (HPLC).