Single-Crystal Particles of Mesoporous Niobium−Tantalum Mixed Oxide

Abstract

Single-crystal particles of mesoporous niobium-tantalum mixed oxide with a wormholelike structure were successfully prepared and characterized. The mixed oxide was prepared by a neutral templating method, and the samples provided have thick walls and an unordered pore structure. Neutral block copolymer, HO(CH 2 CH 2 O) 20 (CH 2 CH(CH 3 )O) 70 (CH 2 CH 2 O) 20 H, and metal chlorides were used as the template and inorganic source in propanol. The crystallized mesoporous single-crystal structures were obtained by a two-step calcination process; the first calcination process removes the template, forming a mesoporous structure with amorphous wall material, and the second calcination process crystallizes the pore walls while maintaining the mesoporosity. The submicrometer mesoporous particles forming the walls were confirmed by transmission electron microscopy to be single crystals. The pore diameter was found to increase upon crystallization, while retaining the open-pore system. N 2 -gas adsorption-desorption analysis indicated that the pore volume of the crystallized sample remained the same as that of the amorphous precursor. The fabricated niobiumtantalum mixed oxide exhibits high thermal, hydrothermal, and mechanical stability.

Lithium transition metal (Ti, Nb, V) oxide mesoporous thin films: Contrasting results when attempting direct synthesis by evaporation-induced self assembly

“…5a. In the case of the 1Nb-0Li-1EO film, the presence of Nb 2 O 5 reflections after 5 minutes at 600°C is in good agreement with the thermal analysis results of Lee et al [32], who report a crystallization temperature of 575°C. On the contrary, 600°C as crystallization temperature of LiNbO 3 in the 1Nb-1Li-1EO film is significantly higher than the 200°C-400°C range reported by other authors [33,34].…”

Enhanced activity of mesoporous Nb2O5 for photocatalytic hydrogen production

“…It would be of great interest to synthesize such Nb-based photocatalysts with mesoporous structure, which, however, has seldom been achieved due to the shortage of effective synthesis method. Up to now, fabrication of niobium oxide (Nb 2 O 5 ) with mesoporous structure has been reported a lot [32][33][34][35][36][37]. The study on mesoporous Nb 2 O 5 has also attracted researchers' attention because of its special properties and its interesting applications, such as chemical sensors, host materials, as well as catalysts [35][36][37].…”

Roles of interfaces in nanostructured composites: nanocatalysts, sponge crystals and thin films

“…Porous (Nb,Ta) 2 O 5 had an ordered structure 33) TEM images showed that all parts of this material had the same crystal orientation. Their TEM images appear to show (Nb,Ta) 2 O 5 grains connected epitaxially with each other.…”