Controlled synthesis of gold nanospheres and single crystals in hydrogel

Narrow-dispersed gold nanospheres, regular single-crystal nanoplates and nanobulks were prepared, respectively, by reducing HAuCl4 within a hydrogel system under UV irradiation. The formation of gold products with different geometric shape and size was found to depend on both the microenvironment of the gel matrix and the initial concentration of HAuCl4. The resultant gold particles were investigated by UV-vis spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy-dispersion X-ray spectroscopy.