Xiang Qing Li

Facile Preparation of AgIn5S8 Pompon-like Microspheres with High Visible Light Photocatalytic Activity

The pompon-like microspheres of AgIn5S8 with a cubic phase were prepared in a low temperature aqueous solution using mercaptoacetic acid as capping agent and thioacetamide as sulfur source and characterized with XRD, UV-vis absorption spectra, SEM and BET analysis. It is interesting that the microspheres are quite open and puffy. More importantly,the obtained microspheres showed remarkable photocatalytic activity for the degradation of methyl orange under visible light irradiation, which is probably due to the pompon-like morphology for providing reactive sites and facilitating the charge transfer between the target pollutant and the photocatalyst. This method could be extended to the synthesis of other functional micro/nano materials.

An Efficient Visible Photocatalytic System Containing Eosin Y, Multiwalled Carbon Nanotubes and CuO for H2 Evolution from Water

In this work, a visible photocatalytic system containing Eosin Y, multiwalled carbon nanotubes and CuO was prepared. The photocatalytic hydrogen evolution from water over this system was studied using triethanolamine (TEA) as a sacrificial reagent. The results indicated that it was an efficient photocatalyst with an average rate of H2 evolution of 373 mmol·h-1·g-1 during first three hours under visible irradiation.

Visible Light Photocatalytic Hydrogen Evolution from Water Reduction Using Eosin y Containing Trace Vitamin B12 as a Light Harvesting Unit

A visible light photocatalytic system consisting of Eosin Y containing trace vitamin B12 (VB12) as a light harvesting unit, multiwalled carbon nanotubes (MWCNTs) as an electron transfer channel and CuO as a hydrogen evolution center (abbreviated to Eosin Y/VB12-MWCNTs-CuO) was prepared on the basis of the synergistic effect between Eosin Y and VB12 under visible light irradiation. The Eosin Y/VB12-MWCNTs-CuO system exhibits a higher photocatalytic activity of hydrogen evolution than the Eosin Y-MWCNTs-CuO system. The improvement of the photocatalytic activity is probably due to the effective transfer of photogenerated electrons and stabilization of VB12 to excited Eosin Y.

One-Pot Synthesis and Visible Light Photocatalytic Activity of AgIn5S8/AgInS2 Composite

A composite of AgIn5S8/AgInS2 was prepared in aqueous solution by a simple low temperature process using mercaptoacetic acid as capping agent and thioacetamide as sulfur source. The composite was characterized by Xray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The obtained AgIn5S8/AgInS2 composite showed high visible photocatalytic activity for the degradation of methyl orange with 97.5% of degradation efficiency of methyl orange under visible irradiation for 10 min. Under same conditions, furthermore, the AgIn5S8/AgInS2 composite displayed better stability than that of pure AgIn5S8 and AgInS2.

Influence of Copper as a Co-Catalyst of Potassium Hexaniobate Nanotubes on the Photocatalytic Hydrogen Evolution from a Methanol Aqueous Solution

In the presence of Cu2+ ions, the photocatalytic hydrogen evolution from a methanol aqueous solution was achieved when potassium hexaniobate nanotubes were used as the catalyst. It was found that there existed a photo-induced period in the initial reaction stage. Furthermore, the photo-induced period was prolonged by increasing the amount of Cu2+ ions. After that, the rate of hydrogen evolution was dramatically improved. Combined with the reaction phenomena and the result of the photocatalytic hydrogen evolution, it was deduced that the Cu2+ ions captured the photo-generated electrons of potassium hexaniobate nanotubes in the photo-induced period. Consequently, the Cu2+ ions were reduced and deposited on the potassium hexaniobate nanotubes. When the mass ratio of Cu to potassium hexaniobate nanotubes was 3 wt%, the rate of hydrogen evolution over the catalyst reached 21.9 mmol·g-1·h-1, which could almost match with Pt as a co-catalyst. These results showed that Cu was an effective alternative to Pt as a co-catalyst of potassium hexaniobate nanotubes for the photocatalytic hydrogen evolution from the methanol aqueous solution.

Photocatalytic Degradation Activity of TiO2 Nanotubes for Cr(VI)

TiO2 nanotubes were obtained by calcining at various temperatures. The influence of calcination temperature on the degradation activity of TiO2 nanotubes for Cr (VI) was investigated under UV light irradiation. It was found that the photocatalytic activity of TiO2 nanotubes calcinated at 350 °C was the highest. Furthermore, the photocatalytic activity of TiO2 nanotubes was higher than that of the P25 TiO2 nanoparticles. Importantly, the stability of TiO2 nanotubes for the degradation of Cr (VI) was high, and degradation efficiency can still reach 72.4% after 8 recycles. Consequently, a highly stable and active photocatalyst for degradation of Cr (VI) was achieved.

Facile Preparation and Photocatalytic Activity of TiO2 Microspheres with a Diameter of 1-8 μm

TiO2 microspheres were prepared in a solvothermal process without involving any templates. Meanwhile, the photocatalytic activity of TiO2 microspheres was studied using p-nitrophenol as a probe. The results indicate that the anatase TiO2 microspheres with a diameter of 1-8 μm can be obtained using this simple method. Moreover, the as-prepared TiO2 microspheres display relatively high visible photocatalytic activity with 35.6% of degradation ratio of p-nitrophenol after 150 min irradiation.

Preparation of HgS Nanoparticles with Adjustable Dispersibility at Water/n-butyl Alcohol Interface

HgS nanoparticles with adjustable dispersibility have been synthesized at the water/n-butyl alcohol interface and characterized with Xray diffraction, transmission electron microscopy. Meanwhile, the dispersibility of the asprepared HgS nanoparticles in water and nbutyl alcohol were measured, respectively. The results indicate that the cubic HgS nanoparticles could be obtained; and the dispersibility of the HgS nanoparticles can be simply tuned. When Hg (CH3COO)2 aqueous solution and nbutyl alcohol solution of thioacetamide are used, the asprepared HgS nanoparticles can be dispersed in water to form a solutionlike suspension. In contrast, when thioacetamide aqueous solution and nbutyl alcohol solution of Hg (CH3COO)2 are used, the oil dispersible HgS nanoparticles are obtained. Moreover, the mechanism about the adjustable dispersibility of HgS nanoparticles is discussed.

Effect of Grinding on the Photocatalytic Activity of Commercial ZnO Powder

The effect of grinding on the photocatalytic activity of commercial ZnO powder was explored using methyl orange as a model pollutant and the corresponding mechanism was discussed tentatively. The results indicate that the photocatalytic activity of the ZnO powder grinded decreases obviously in comprison with that of the ZnO powder untreated. This phoenomenon might be ascribed to the decrease of surface defects of ZnO induced by grinding, suggesting that the further treatment leading to the change of surface states of ZnO powder as a photocatalyst ought to be avoided.

Loading of HgS Nanoparticles on the Silica Microspheres

HgS nanoparticles were loaded on the silica microspheres by an improved layer-by-layer self-assembled technique following low temperature heat-treatment. The optical properties of HgS nanoparticles on the silica microspheres were characterized with UV-vis and fluorescence spectra. The results suggested that the HgS nanoparticles were formed on the silica microspheres, and the average size of particles was approximately 15 nm. The direct band gap of the loaded HgS nanoparticles was calculated to be 2.4 eV from the absorption spectrum, which was blue-shifted by 0.4 eV from its bulk value due to quantum size effect. The photoluminescence showed a broad emission around 440 nm from sulfur vacancies. These results indicate that the optical properties of HgS nanoparticles loaded on the silica microspheres are similar to those of free HgS nanoparticles, which is encouraging for potential applications.