A facile and green approach to synthesize Pt@CeO2 nanocomposite with tunable core-shell and yolk-shell structure and its application as a visible light photocatalyst

We report a very facile and green template-free hydrothermal approach to synthesize Pt@CeO2 nanocomposite in an aqueous phase with tunable core-shell and yolk-shell structure. The formation of such core-shell and yolk-shell Pt@CeO2 nanocomposites can be reasonably explained by a novel mechanism of combined synergy interaction of heterogeneous seeded growth process and Ostwald ripening process, which is distinctly different from the well-known physical phenomena, such as nanoscale Kirkendall effect, Ostwald ripening and oriented attachment, employed in wet-chemistry fabrications of core/yolk-shell inorganic nanostructures. Interestingly, we show that, using selective oxidation of benzyl alcohol as a probe reaction at room temperature and ambient pressure, the incorporation of Pt into the shell of semiconductor CeO2 can remarkably enhance the photocatalytic performance of CeO2 for selective oxidation of alcohol. This represents a first example on the application of metal core@semiconductor-oxide shell nanostructured composite materials as visible-light-driven photocatalyst to selective oxidation reactions. Therefore, our findings could not only offer a useful direction on scale-up fabrication of other metal-oxide-coated noble metal nanocomposites with tunable core/yolk-shell structure, but also point to promising vistas of such metal core@oxide shell semiconductor nanocomposites as a novel class of materials platform as visible-light-driven photocatalyst in selective organic transformations.