Lijun Han

Controlled synthesis of CdS micro/nano leaves with (0001) facets exposed: enhanced photocatalytic activity toward hydrogen evolution

Two-dimensional CdS micro/nano leaves have been synthesized via a controlled hydrothermal process. The dimensions of the leaves is in the range of 4–6 μm and the thickness of the leaves is 30–50 nm. The surface of the leaves is smooth and composed of several parallel laminar layers with multi-steps. The SAED and HRTEM images indicated that the surface of the leaves was mainly composed of (0001) plane and all the leaves had single-crystallinity. The morphology of the as-prepared products could be controlled by adjusting the concentration of hydrofluoric acid (HF). The effects of HF concentration, reaction temperature and time were investigated. A possible formation mechanism is proposed based on the intrinsic crystal structure and selected adsorption processes. In addition, the as-prepared CdS pinnate leaves showed enhanced photocatalytic activity toward hydrogen evolution under visible light irradiation. The efficiency of micro/nano leaves was more than 6 times greater than normal CdS microparticles.

A strategy for synthesis of ionic metal-organic frameworks.

For the first time, we designed and synthesized a new kind of ionic metal-organic framework with lanthanide ions and a carboxyl-functionalized ionic liquid, including [Er(4)(mu(3)-OH)(4)(mu(2)-O)(0.5)OL(4)(H(2)O)(3)] x Br(2.90) x Cl(1.10) x 2 H(2)O (MOF-1) and [PrL(H(2)O)(4)Cl] x Br x H(2)O(MOF-2).

Controlled synthesis of double-shelled CeO2 hollow spheres and enzyme-free electrochemical bio-sensing properties for uric acid

A simple solvothermal method has been used to synthesize novel double-shelled CeO2 hollow spheres (HSs) in a mixed solvent of PEG-400 and H2O. The structure and morphology of the CeO2 HSs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption isotherms. The SEM and TEM images indicated that the as-prepared double-shelled CeO2 (about 400–500 nm in diameter) were aggregates of nanoparticles with sizes of about 15 nm. The shape and composition of the as-obtained products could be controlled by adjusting the ratio of PEG-400 and H2O in the solvothermal process. The effects of PEG-400/H2O ratio, solvothermal temperature and reaction time on the morphology evolution of as-prepared products were investigated, and the possible formation mechanism was proposed based on nucleation and the Ostwald ripening process as well as the soft-template function of PEG-400. In addition, the double-shelled CeO2 HSs show high electrocatalytic activity towards uric acid (UA) oxidation and thus exhibit good biosensor activities toward the detection of trace amounts of UA.

Photocatalytic reduction of CO2 with H2O on CuO/TiO2 catalysts

ABSTRACT Carbon dioxide was photocatalytically reduced to produce methanol and ethanol in the presence of CuO-loaded titania powders suspended in water containing Na2SO3 as the hole scavenger. The photocatalysts were synthesized by an impregnation method using P25 (Degussa) as support. At the optimum amount of copper oxide loading (3 wt%), the methanol and ethanol yields were 12.5 and 27.1 μmol/g-catal., respectively, following 6 h of UV illumination. The redistribution of photogenerated charge carriers in CuO/TiO2 facilitates electron trapping and prohibits the recombination of electrons and holes, which significantly increases photoefficiency. The addition of Na2SO3 promotes the formation of ethanol.

Batch analysis of H-2-rich gas production by coal gasification using CaO as sorbent

ABSTRACT In this study, a clean coal gasification technology was developed for production of H2-rich gas from coal with CaO as sorbent. The conditions including [CaO]:[C] ratios, reaction temperature, and reaction time for the coal gasification process were optimized. The products were H2, CH4, CO, and CO2. The highest H2 percentage (82.66%) for bituminous coal was obtained at [CaO]:[C] = 2:1 and T = 1203 K. Meanwhile, the highest H2 percentages for high-sulfur coal and high-sulfur coke were 77.41 and 81.57% at [CaO]:[C] = 1:4 and T = 1203 K, respectively. Moreover, the residual H2S were 0.28 and 2.19%, correspondingly.

Study on the hydrotreatment of C9 aromatics over supported multi-metal catalysts on gamma-Al2O3

With the dramatic increasing of economy, the conflict between the lack of petroleum resource and sharply increasing demand for gasoline and diesel has restricted the continuous development of economy and energy of our world. The catalytic conversion of C9 aromatics into clean fuel was studied in our laboratory using hydrotreating catalysts which were prepared by new synthesis technologies that combine vacuum-impregnation and temperature-programmed calcinations. Characterization results indicate that these catalysts have a high surface area, and the activity sites dispersed well on the supporter. Hydrogenation performance of reaction conditions was carried out in two-stage fixed beds. Products of gasoline (<180 °C) and diesel (180–360 °C) fractions were separated from intermediate products via distillation, and the analysis results demonstrate that S/N content, density, and viscosity decreased. However, the H/C molar ratio increased. The main reactions of isomerization, disproportionation, and dealkylation occurred during the conversion of C9 aromatics and the activity order accorded the mechanism of carbenium ion reaction. This study indicates that C9 aromatics could be considerably upgraded through catalytic hydroprocessing to high-quality fuel in the presence of high-performance catalysts and appropriate reaction conditions. Thus, they are promising catalytic technologies and materials. Furthermore, the products could substitute gasoline and diesel partly.