ZnO:Au nanocomposites with high photocatalytic activity prepared by liquid-phase pulsed laser ablation

This paper presents a simple and feasible method for liquid-phase fabrication of Au-decorated ZnO (ZnO:Au) nanocomposites by two-step liquid-phase pulsed laser ablation. Pristine ZnO were first prepared by pulsed laser ablation of zinc powers in water, and ZnO:Au nanocomposites were then synthesized by decorating the pristine ZnO with Au nanoparticles also via liquid-phase pulsed laser ablation. The prepared ZnO:Au NCs were characterized in liquid and solid phases for morphology, structure and optical properties, and used as photocatalysts for the evaluation of photocatalytic activity. The ZnO:Au nanocomposites are composed of Au nanoparticles surrounded by polycrystalline wurtzite ZnO, present high light absorption in the ultraviolet and visible region and have a plasmonic absorption band around 530 nm. Unlike pristine ZnO which has photocatalytic activity only in the ultraviolet region, the incorporation of Au nanoparticles with ZnO results in high photocatalytic activity in the ultraviolet as well as in the visible region by significantly enhancing the photogeneration of charge carriers and promoting the separation of the photogenerated charge carriers. Using Rhodamine B as a representative organic pollutant, the ZnO:Au nanocomposites were demonstrated to exhibit excellent photocatalytic performance as visible photocatalysts for the degradation of organic pollutants. Compared with pristine ZnO, the rate constant for the photodegradation of Rhodamine B with the ZnO:Au nanocomposites is nearly doubled under visible illumination.