Roles played by polysaccharides with different structures in biomimetic synthesis of cuprous oxide

Abstract

In this study, several polysaccharide derivatives, carboxymethyl cellulose sodium (CMC), carboxymethyl chitin (CMCH) and sodium alginate (HCM), were introduced as the template in the preparation of Cu₂O. Polysaccharides mainly serve as templates by selectively adsorbing onto the {111} faces of Cu₂O crystals. The different adsorption thicknesses of the polysaccharide adsorption layers on the {111} surfaces and crystal corners of the Cu₂O crystals cause Cu₂O crystals to transform from octahedrons to octa-pods. The relative adsorption tightness (AC) of the three polysaccharides on the {111} planes of Cu₂O crystals are AC_(HCM) > AC_(CMCH) > AC_(CMC), which leads to intact Cu₂O octa-pods, octa-pods with apex angles that are smaller plates or shallower pits, and octa-pods with apex angles that are depressed pits, respectively. In addition, to our knowledge, it is the first time that Cu₂O octa-pods with jagged crystalline edges are obtained by using the CMC template and Ostwald ripening process. Selective adsorption of the polysaccharide template on the {111} plane of the Cu₂O crystal can prevent the effect of external conditions, such as the initial reaction temperature, on {111} faces, which effects the morphology of the ultimate Cu₂O crystal and favors the retention of the {111} surface. Polysaccharide adsorption layers with different thicknesses in different parts of the Cu₂O crystal can be used to form Cu₂O octa-pods with significantly increased foot lengths cooperating with a high concentration alkali solution.