Photoluminescence of Colloids of Pristine ZnAl Layered Double Hydroxides

Colloids of pristine ZnAl layered double hydroxides (LDHs) were found to display an unexpected photoluminescence (PL) phenomenon disparate from the corresponding LDH solids. First, ZnAl LDHs with nitrate in the interlayer were prepared by a hexamethylenetetramine hydrolysis method. Their colloids were obtained by subsequent delamination in formamide at room temperature. Interestingly, an unexpected PL phenomenon was observed for the colloids, different from that of the relevant solid powder. The Zn/Al ratio and concentration did not change the Stokes shift. However, they were found to be the major factors in the emission intensity. Numerous surface defect sites and interaction of LDH with formamide were believed to be the main reasons.