Hybrid TiO₂-ZnO Nanomaterials Prepared Using Laser Ablation in Liquid

Hybrids of semiconductor nanomaterials often demonstrate properties that are superior to those of their components. In this study, we prepared hybrid nanomaterials of TiO₂ and ZnO, which are among the most actively studied semiconductors, by means of millisecond-pulsed laser and analyzed how their morphology, particle size, and surface composition depend on preparation conditions. A series of nanomaterials were obtained via sequentially ablating Zn and Ti metal plates (in different sequences) in water, while laser pulses of lower (2.0 J/pulse) and higher (5.0 J/pulse) energy were applied. The properties of laser-produced hybrid TiO₂-ZnO nanomaterials were shown to be governed by experimental conditions such as laser pulse width, pulse peak power, and reaction media (either pure water or colloid with nanoparticles). The morphology revealed nanospheres of TiO₂ that decorate nanorods of ZnO or flower-like aggregates of zinc oxide. Intriguingly, after extended ablation time, titania was found to be self-doped with Ti³⁺ and Ti²⁺ ions, and the contribution of lower oxidation states of titanium could be controlled by the applied laser pulse energy. The physicochemical characteristics of hybrid nanomaterials were compared with pure ZnO and TiO₂ prepared under the same laser conditions.