Qingyi Lu

The assembly of semiconductor sulfide nanocrystallites with organic reagents as templates

An organic reagent-assisted method has been developed for the synthesis and assembly of copper sulfide, cadmium sulfide and silver sulfide nanocrystallites at low temperature under hydro- or solvothermal conditions. Nanowire-like aggregates (with an average diameter of 120 nm and length of 2 μm) assembled by digenite phase copper sulfide nanoparticles, nanotube-like aggregates (with diameters ranging from 40 to 200 nm and lengths from 400 nm to 4 μm) and nanovesicle-like aggregates (with size ranging from 50 to 180 nm) assembled using djurleite phase copper sulfide nanoparticles have been obtained using triethylenediamine, tramethylethylenediamine and di-n-butylamine as the linking agents, respectively. A cetyltrimethyl-ammonium bromide-assisted solvothermal process with CdCl2 and thiourea as the reactants and ethylenediamine as the solvent has been proposed to control the length of the CdS nanorods from 300 nm to 4.5 μm and construct novel CdS nanorod-based structures, including polydentate wire-like architectures and polydentate sphere-like architectures composed of dozens of CdS nanorods of 10 nm in width and 100 nm in length. A CH3(CH2)11SH-template method has been adopted to realize the synthesis and the simultaneous assembly of silver sulfide nanocrystallites with AgNO3 and Na2S as reactants. By changing the reaction temperature and the dodecylthiol concentration, two-dimensional orthogonal and hexagonal-like ordered silver sulfide nanoparticle arrays and quasi-orthogonal silver sulfide nanorod arrays can be obtained. This organic reagent-assisted route is very simple and can be extended to the synthesis and assembly of other semiconductor sulfide nanocrystals.

In situ adsorption method for synthesis of binary semiconductor CdS nanocrystals inside mesoporous SBA-15

Abstract Binary semiconductor CdS nanocrystals have been prepared inside the channels of mesoporous SBA-15 using an in situ adsorption method combining a surface modification scheme and a wet impregnation technique by functionalizing the SBA-15 surface with thiol groups, adsorbing cadmium cations, and calcining in N 2 atmosphere at 300 °C. The combined results of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) firstly reveal that CdS nanocrystals with uniform size of about 6 nm are formed and mono-dispersed inside the channels of mesoporous SBA-15. And a blue shift is observed in UV–Vis absorption spectrum and photoluminescence (PL) spectrum, indicating the quantum size effect of nanocrystalline CdS.

A template-free method for hollow Ag2S semiconductor with a novel quasi-network microstructure

Abstract A simple and convenient method, free of any template, has been proposed to synthesize hollow Ag2S semiconductor with a novel network-like microstructure under hydrothermal conditions with AgNO3, thiourea (Tu) and hydrochloric acid as reagents. The ratio of AgNO3 to Tu, the reaction temperature and the addition of hydrochloric acid are of importance to the formation of the hollow network-like microstructure.

Synthesis of germanium oxide mesostructures with a new intermediate state

Highly ordered hexagonal GeO2 mesostructure has been firstly synthesized by using surfactant-templated approach under basic hydrothermal conditions. The surfactant/inorganic species ratio is found to have a critical effect on the formation of GeO2 mesostructure. At low surfactant/inorganic species ratio, a new intermediate state of GeO2 mesostructure with novel bundle-like morphology has been obtained. By further controlling the surfactant concentration in a certain range, the length of the bundle-like structure can be adjusted from dozens of nanometers up to several micrometers. The possible synthetic mechanism has been proposed to simulate the formation of the new intermediate state.

Synthesis of mesoporous silica with novel structures using rigid bolaform ammonium surfactants

Mesoporous silica with a novel Structure (FDU-11) has been prepared for the first time by using a rigid bolaform tetra-head-group quaternary ammonium surfactant: [(CH3)(3)NCH2CH2CH2CH2N(CH3)(2) CH2(CH2)(11)OC6H4C6H4O(CH2)(11)CH2N(CH3)(2)CH2CH2CH2N(CH3)(3)](4+)center dot 4Br(-) under an alkaline condition. X-ray diffraction (XRD) and transmission electron microscope (TEM) studies show that the mesoporous silica FDU-11 may have a low symmetric tetragonal mesostructure with P4/mm:space group. N-2 sorption isotherms show that calcined mesoporous silica FDU-11 has the BET surface arc of 281 m(2)/g, pore size of 2.05 nm and the pore volume of 0.36 cm(3)/g. A phase transformation from FDU-1 into another unknown mesoporous silica structure by a hydrothermal treatment is observed, suggesting intermediate nature of the FDU-11 mesophase.

A one-step synthesis of monolithic silica/block copolymer/metal sulfide composites with ordered mesostructure

Abstract A generalized one-step synthesis strategy is proposed for preparing monolithic silica/block copolymer mesostructured composites doped with different metal sulfides. The materials were characterized by small-angel X-ray diffraction (XRD) and ultraviolet-visible diffused reflection spectra (UV-DRS). The results show that the long-range regularity of the mesostructured silica hosts and the quantum-confined effect of the small-sized semiconductive metal sulfides are well combined for the derived composites, which makes the composites possess tunable optical properties.