The ability of a fibrous titanium oxophosphate for nitrogen-adsorption above room temperature

Abstract

TiO(PO)·2HO (1), a three-dimensional titanium oxophosphate, thermally transforms to TiO(PO) (2), a fibrous novel compound. The crystal structure of 2 was solved ab initio using powder X-ray diffraction data (triclinic, P1[combining macron], a = 5.0843(1) Å, b = 8.6121(2) Å, c = 9.6766(2) Å, α = 74.501(2)°, β = 76.146(2)°, γ = 74.488(3)°, Z = 2). Compound 2, containing both 4- and 6-fold coordinated titanium atoms, shows measurable thermally activated nitrogen-adsorption. To our knowledge, the process described here constitutes the first example of nitrogen-fixation by an inorganic material at above-ambient temperature.

Structural and proton conductivity studies of fibrous π-Ti2O(PO4)2·2H2O: application in chitosan-based composite membranes

“…HRTEM inspection showed the lattice fringes on the π-TiP_0 nanorods in several directions, demonstrating the crystallinity of the nanorods (Figures 4 and 5). Compared with the ρ-TiP polymorph, 25 the π-TiP_0 generally shows less crystallinity and more crystalline defects. Although there are slight differences in the measured d hkl values, most probably due to the electron beam damage, the indexing has confirmed the structural information determined relying on PXRD.…”

“…23,24 The internal porosity can be altered by the thermally induced elimination of stoichiometric water molecules resulting in a substantial increase of nitrogen adsorption at 100-300 °C. 25 Yada et al synthesized superhydrophilic thin films consisting of π-TiP micro-and nanocrystals bearing controlled morphologies. 26 In addition, TiP can be converted to superhydrophobic surfaces when modified with alkylamine molecules.…”

Crystal Structures of Two Titanium Phosphate-Based Proton Conductors: Ab Initio Structure Solution and Materials Properties

“… 20 Two open-framework structures, Ti 2 O(PO 4 ) 2 ·2H 2 O, and its dehydrated form, Ti 2 O(PO 4 ) 2 , are also formed by [PO 4 ] 3– and TiO 6 polyhedra. 16 , 21 Both structures contain two one-dimensional chains, [P n O 3 n ] n − , along the crystallographic a axis with n = 6 and 8. 16 , 21 , 22 In Ti 2 O(PO 4 ) 2 ·2H 2 O, one of the two independent titanium sites is coordinated by two water molecules, forming a highly distorted TiO 6 octahedron.…”

“…In the dehydration process, the titanium coordination changes to a TiO 4 tetrahedron, creating new acidic sites on the surface of the particle. 16 …”

“…They show promising behavior as photocatalysts, solid acids, N 2 absorbents in the Haber−Bosch process, and proton conductors, in particular in the mediate temperature range. 5,6,16,17 The wide application range of titanium phosphates is caused by their structural variety. The structure of monoclinic metaphosphate Ti(PO 3 direction.…”