关键词氧化锆 纳米材料 有序多孔氧化锆
This paper focuses on the synthesis of thermally stable mesostructure zirconium oxide with a surfactant templating technique. It was shown that the suitable molar ratio of the surfactant to zirconium as well as the suitable temperature of the hydrothermal treatment are of great importance in the synthesis of high quality porous zirconium oxide material. Besides, under the suitable concentration treatment, the phosphoric acid can greatly enhance the thermal stability of the porous material.
Photoluminescence (PL) measurements show that two strong PL bands were emitted at room temperature in the ordered porous zirconium oxide material. The UVVis spectroscopy and Electron Paramagnetic Resonance (EPR) spectroscopy were adopted for the investigation on the PL effects. It was concluded that the two PL bands are related to the structure of the porous oxide. In addition, the suitable treatment concentration of phosphoric acid is believed to be an important parameter to generate the PL responses. The significant optical properties of this new material may be very interesting for its potential application in the photoelectric fields.
On the basis of the successful synthesis of high quality zirconium oxide with ordered pore structure, various techniques have been developed to modify the ordered porous ZrO〓, as to explore more interesting chemical and physical properties for possible applications. X-ray powder diffraction, N〓 adsorption analysis, HRTEM, Raman, XPS, UV-Vis spectroscopy, and EPR spectroscopy were adopted for the characterization of the synthesized materials.
The ordered porous zirconium oxide incorporated with high amounts of titanium was reported in the paper for the first time, via a direct-hydrothermal synthesis procedure. The experimental results show that titanium ions are homogeneously dispersed into the framework of ZrO〓, when the amount of titanium doping is not higher than 20mol％. And a suitable amount of titanium incorporation is favorable to the thermal stability of the porous zirconium oxide. Furthermore, the increased intensity of absorption peaks and the magnitude of red-shift of the adsorption bands correspond well to the amount of the Ti incorporation. These new Ti-ZrO〓 materials may be potentially useful as novel catalytic or photoelectric materials.
Cerium incorporated ordered porous zirconia materials have been prepared by a solution grafting method. EPR analysis was adopted for the characterization of the surface oxygen properties of the synthesized materials. It was shown that small amount of cerium had been successfully incorporated into the framework of ZrO〓 at a cerium loading not higher than 4mol％. The excess cerium was separated out as CeO〓 nano-crystallites on the surface or in the pore channels. The synthesized ceria/zirconia porous material shows excellent oxidation and reduction properties. Also, the amount of cerium used can be much reduced than that in the traditional method. After further loading with the noble metal Pt, the temperatures for catalysis reduction of the ceria/zirconia porous material can be greatly decreased, which could be expected to have important applications in practical catalysis.
Manganese oxide nanoclusters were synthesized within ordered porous ZrO〓 by using wet impregnation technique. The results indicate that the nanoclusters of manganese oxide could be successfully confined and uniformly distributed into the pores of ZrO〓. XRD and TEM investigations showed that the ordered porous host structure was still maintained after loading with MnO〓. The UV-absorption edge is found to have a significant red-shift at the elevated heat treatment temperature, and the grow of the nanoclusters have shown to be restrained by the dimension of the pore channels. EPR measurement shows that there is a significant change in their magnetic property of the nano-sized clusters which were confined in the pore channels as compared to ordinary MnO〓 particles. In addition, the excellent oxygen adsorption properties of the manganese oxide clusters confined in the pore channels have been found by a O〓-TPD analysis. It is believed that the active catalysis centers include both the lattice oxygen of MnO〓 as well as the surface adsorbed oxygen on the Mn/ZrO〓 material surface. It could be expected to have potential applications in catalysis or be used as a novel paramagnetic material.