Core-shell TaxO@Ta2O5 structured nanoparticles: laser ablation synthesis in liquid, structure and photocatalytic property

Monodispersed, homogeneous core-shell TaxO@Ta2O5 (x = 1, 2) composite nanoparticles (NPs) are successfully synthesized via one-step liquid phase laser ablation (LPLA) of a tantalum metal plate in ethanol. The morphology, phase structure, and surface states of the core-shell NPs are investigated by scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The LPLA-derived spherical-like NPs consist of well-crystallized TaxO cores with diameters of 10-40 nm and amorphous-like Ta2O5 shells with a thickness of ca. 5 nm. A possible formation pathway for TaxO@Ta2O5 core-shell NPs is proposed on the basis of LPLA and subsequent reactive quenching processes. Photocatalytic degradation of methylene blue in the liquid phase serves as a probe reaction to evaluate the activity of the as-prepared core-shell NPs under the irradiation of UV light. Theoretical calculation based on density functional theory indicated the metallic nature of the core TaO phase. Interestingly, compared with pure Ta2O5 powders, the incorporation of suboxide TaxO cores into the shell of Ta2O5 contributes to an enhancement in photocatalytic activity. This work provides new information that may be used for the design and novel application of homogeneous core-shell nanostructures.