Watching the growth of aluminum hydroxide nanoparticles from aluminum nanoparticles synthesized by pulsed laser ablation in aqueous surfactant solution

Aluminum nanospheres were prepared by a pulsed Nd-YAG laser ablation method in aqueous surfactant, cetyltrimethylammonium bromide (CTAB), solutions. In the absence of CTAB but with aging, fast hydrolysis reaction between Al and water changed the composition and structures of Al nanospheres to Al oxides and then further to Al hydroxides, bayerite and gibbsite, via a dissolution–recrystallization process. Thus, the control of the hydrolysis rate, producing pure Al and Al hydroxide nanoparticles selectively was attempted by varying the concentration of CTAB in the pulsed laser ablation solution; the transformation processes from Al to Al hydroxides were monitored. The resulting nanoparticles at each development stage were analyzed by X-ray diffraction measurements, field emission scanning electron microscopy, high-resolution transmission electron microscope observations, fast Fourier transform analysis, and energy dispersive spectrometer analysis. Possible mechanisms for the dissolution–recrystallization process of Al hydroxides are proposed.