MCM-41-CdS nanoparticle composite material: Preparation and characterization

Abstract

The preparation and characterization of a hierarchical material constituted by a mesoporous silica MCM-41 whose mesochannels contain CdS nanoparticles capped with both bis(2-ethylhexyl) amine and bis(2-ethylhexyl) sodium sulfosuccinate is reported. MCM-41 powder was synthesized by using the LCT methodology. CdS nanoparticles were obtained within the inversed micelle core of a water/AOT/n-heptane microemulsion. Nanoparticles growth was followed by means of UV–Vis spectroscopy and was inhibited by BEA addition. The CdS-capped nanoparticles were separated by centrifugation, washed with water and ethanol and finally dispersed in n-heptane. The insertion of CdS nanoparticles into MCM-41 mesochannels was obtained by adding mesoporous silica into the n-heptane nanoparticles dispersion. The yellow MCM-41-CdS nanoparticles composite was characterized by using different structural (X-ray diffraction, nitrogen adsorption–desorption isotherm and small angle neutron scattering coupled with the contrast variation method), spectroscopic (diffuse reflection UV–Vis, attenuated total reflection and diffuse reflectance Fourier transform infrared) and morphological techniques (high resolution transmission electron microscopy). The CdS nanoparticles, significantly capped by both the amine and the surfactant molecules, were found to be localized inside the cylindrical silica pores. The mesoporous material loses its long-range order while the incorporation process does not affect the size and electronic structure of CdS nanoparticles.