Synergetic effect of interface and surface on photocatalytic performance of TiO2@ hollow CeO2 core–shell nanostructures

Abstract

The photocatalytic performance of new TiO 2 /CeO 2 composites is reported and the mechanism for its enhancement with respect to bare TiO 2 and CeO 2 nanoparticles is revealed. With a two-step process, TiO 2 shells were deposited on CeO 2 hollow cores forming the composites (TiO 2 @H-CeO 2 ). With tuning the shell deposition, optical properties were engineered. The absorption range was extended to visible light and the lifetime of photoinduced electron-hole pairs were prolonged. Photo-degradation experiments indicate that the removing of 10 -5 M methylene blue by TiO 2 @H-CeO 2 was improved under both UV and visible light. The highest degradation rate constant K reached 0.023 min − 1 under visible light showing an enhancement of more than one order of magnitude as compared to solely TiO 2 or CeO 2 nanoparticles. High-resolution electron energy loss spectroscopy was utilized to investigate both surface and interface areas. It demonstrates a strong interface interaction between CeO 2 and TiO 2 after forming core-shell structure with the introduction of a nanometrical interface layer and a modification of the Ce 3+ and Ti 3+ content near the interface. The present work revealed that the photocatalytic efficiency can be improved effectively by optimizing the synergistic effect of interface through adjusting the TiO 2 deposition process.

Catalytic activity of CeO2@TiO2 for environmental protection

“…In addition, the change in the band gap occurs as a result of the interaction of ceria and titania in the CeO 2 @TiO 2 core-shell structure. 18,[21][22][23] It is also possible to oxidize dyes due to not only the Fe 3+ /Fe 2+ redox pair, but also Ce 4+ /Ce 3+ and Ti 4+ /Ti 3+ at the interface, [24][25][26][27][28][29] which is further confirmed by the washing out of iron, cerium and titanium into the solution. The mobility of the oxygen lattice also seems to make a small contribution to the Fenton process of oxidative degradation of dyes.…”

Enhanced Photocatalytic Performance of TiO2@CeO2 Hollow Structure through Synergetic Surface and Interface Engineering

“…In such a two-layered structure, the interface region is Ce 3+ -rich, while the surface of the TiO 2 layer is Ti 3+rich. [24] The reaction with low concentration Ce(NO 3 ) 3 ⋅6H 2 O solution results in the Ce 3+ doping into the TiO 2 shell and ceria adsorption on the surface (type I). A change in the crystallinity of the TiO 2 , as observed by XRD and different XAS signatures probed on the Ti absorber, both indicate changes in the Ti─O bonding associated with the functionalization with the ceria.…”

“…Recently, a facile two-step method was developed to prepare TiO 2 @H-CeO 2 submicron hollow composites with promising photocatalytic properties. [24] The hollow structure is featured by its low density and high surface area, providing more active sites at the surface. However, the efficiency was limited by the relatively limited amount of interfacial area in these TiO 2 @H-CeO 2 composites.…”