Photo-promoted in situ reduction and stabilization of Pd nanoparticles by H at photo-insensitive SmO nanorods.

Controlled synthesis of noble metal nanoparticles with well-defined size and good dispersion on supports has been a long-standing challenge in heterogeneous catalysis. Here we report a facile photo-assisted Hin situ reduction process to synthesize monodispersed Pd nanoparticles with 2-4 nm size on photo-insensitive SmO rare-earth metal oxide with nanorod morphology. Thanks to the contribution of UV irradiation, the photoelectrons generation in the SmO support accelerates the H reduction of Pd ions into Pd and stabilize the growth of very small Pd nanoparticles homogeneously dispersed on the support. The homogeneous distribution of the Pd NPs on the surface of SmO is most likely attributed to the profuse nucleation sites created by the UV irradiation and the abundance of hydroxyl groups on the support. The hydrogenation of styrene to ethylbenzene was studied as a model reaction. As a result, the UV radiated sample shows an excellent TOF value of 7419 h, which is quadruple of the sample without UV irradiation, under the condition of 0.1 MPa H at a content of 1.0 wt% Pd. Besides, UV radiated sample shows a negligible performance degradation during the repeated cycling process. This photo-promoted H reduction process provides a convenient and straightforward route for assembling materials with novel structures and functions for nanotechnology applications.