Colloidal construction of porous polysaccharide-supported cadmium sulphide

A method for preparing CdS nanoparticles within the porous confines of a mesoporous starch gel is described. This method utilises the combined colloidal and flexible chemical nature of a porous polysaccharide (i.e. starch) gel to limit CdS growth. The resulting hybrid gels can be dried to produce CdS/starch materials with high surface areas, predominantly mesoporous characteristics and scope for high CdS loading. The synthesis is conducted in aqueous alcoholic solutions without the need for expensive preparation techniques or additional protection/templating strategies. Materials were prepared at increasing CdS loadings on the starch gel, which confined nanoparticle growth and directed size/surface coverage, dispersion and UV-vis absorption profile. The resulting powders presented large mesopore domains with high volumes (pore diameters > 10 nm; V-meso > 0.5 cm(3) g(-1)) and surface areas (S-BET > 170 m(2) g(-1)), interestingly effectively increasing with CdS loading. The synthesised CdS nanoparticles were characterised in the 5-40 nm range of a cubic crystalline structure, increasing in size with loading. A complete surface coverage of the starch gel structure occurs at a CdS/starch ratio = 1 (w/w), allowing the synthesis of a unique mesoporous CdS/polysaccharide hybrid. The presented route is simple, green and in principle extendable to a wide range of QDs and polysaccharide gels, whereby the porous polysaccharide gel acts as the deposition point of Cd2+, directing and stabilising both the growth of the inorganic CdS phase and the expanded high surface area polysaccharide form. (C) 2014 The Authors. Published by Elsevier B.V. All rights reserved.