D-glucose-derived polymer intermediates as templates for the synthesis of ultrastable and redispersible gold colloids

A two-stage hydrothermal process was developed for the synthesis of highly dispersed An colloids. In the first stage, a novel glucose-derived polymer template was prepared by the hydrothermal treatment of glucose at 160 degrees C. This template was then further used in the next step to synthesize highly dispersed gold (An) colloids by hydrothermal treatment with HAuCl4. The templates treated at 160 degrees C with changing reaction times had different templating effects toward An species. The 3-h treated template was able tightly adhere to the An colloids. As a result, an unusual stability was observed for the prepared An particles that could be repeatedly precipitated and redispersed with the template in H2O and were also stable against heating (below 160 degrees C) and aging. Meanwhile, the 5-h and 7-h treated templates had much poorer templating effects to Au species, leading to severe aggregation of the An colloids immobilized on them. The various templating effects were correlated to the different structural features of the templates. Compared to the 5- or 7-h treated templates that were deeply carbonized, the 3-h treated template was only slightly carbonized, thus possessing a lot of functional and hydrophilic O-containing groups that could bind to Au species. These differences in templating ability were also observed in the An samples prepared by the sonication-assisted method. The highly dispersed An colloids immobilized on the 3-h treated template were tested for CO oxidation, and a good catalytic activity and stability for CO oxidation was observed.