Facile assembly of cadmium sulfide quantum dots on titanate nanobelts for enhanced nonlinear optical properties.

A facile route to assemble cadmium sulfide (CdS) quantum dots (QDs) uniformly on the surface of titanate nanobelts (TNBs) through electrostatic interactions is demonstrated. The photophysical properties of the resulting TNB-CdS nanostructured composite, including optical limiting properties, were studied using ultraviolet-visible absorption spectroscopy, photoluminescence spectroscopy, and the open aperture Z-scan technique in the nanosecond regime using a laser with a wavelength of 532 nm. The linear and nonlinear optical properties of this composite nanostructure were strongly influenced by a possible charge/energy transfer process between the QDs and TNBs. The as-prepared TNB-CdS composite offers an optical limiting effect that is superior to that of unmodified CdS QDs and TNBs. The main contributors to the enhanced optical limiting effect in the TNB-CdS composite were a combination of nonlinear scattering and increased nonlinear absorption resulting from efficient charge/energy transfer at the CdS/TNB interface.