RT Journal Article
T1 Structural and Proton Conductivity Studies of Fibrous π-Ti2O(PO4)2·2H2O: Application in Chitosan- Based Composite Membranes
A1 Babaryk, Artem A.
A1 Adawy, Alaa
A1 García, Inés
A1 Trobajo, Camino
A1 Amghouz, Zakariae
A1 Pérez-Colodrero, Rosario Mercedes
A1 Cabeza-Díaz, Aurelio
A1 Olivera-Pastor, Pascual
A1 Bazaga-García, Montse
A1 Dos-Santos-Gómez, Lucía
K1 Conductividad eléctrica
K1 Protones
K1 Materia - Estructura
AB Although the fibrous polymorphic modification of titanium phosphate, π-Ti2O(PO4)2·2H2O (π-TiP) is known for decades, itscrystal structure has remained unsolved. Herewith we report the crystal structure of π-TiP at a room temperature,determined from the synchrotron radiation powder X-ray diffraction, and corroborated by 31P solid state NMR and theaccurate density functional theory calculations. In contrast to the previously reported ρ-TiP polymorph, the as-synthesizedhydrated phase crystallizes in the monoclinic system (P21/c, a = 5.1121(2) Å, b = 14.4921(9) Å, c = 12.0450(11), β =115.31(1)°, Z=4) and is composed of corner-sharing titanium octahedra and phosphate units arranged in a pattern distinctof ρ-TiP polymorph. The unit cell was confirmed by SAED, while the formation of planar packing imperfections and stackingfaults along the [101] was revealed by HRTEM analysis. In situ dehydration study of π-TiP, monitored by high-temperaturepowder X-ray diffraction, led to a new anhydrous monoclinic [P21/c, a = 5.1187(13) Å, b = 11.0600(21) Å, c = 14.4556(26),β = 107.65(2)°, Z=4) phase that crystallizes at 500°C. The latter resembles the packing fashion of the parental π-TiP, albeittitanium atoms are present both in distorted tetrahedral and octahedral coordination environments. Anhydrous π-TiP wasfound to partially rehydrate at room temperature adopting reversibly the structure of the initial phase. The studies carriedout under different conditions of leaching and impregnation with H3PO4 showed that π-TiP exhibits an extrinsic protonconductivity (1.3·10−3 S·cm−1 at 90 °C and 95% RH) due to the presence of protonated phosphate species bounded on theparticles surface, as revealed by 31P MAS-NMR spectroscopy data. The composite membranes of Chitosan (CS) matricesfilled with H3PO4-impregnated π-TiP solid show an increment of proton conductivity up to 4.5·10–3 S·cm–1, at 80 °C and 95%RH, 1.8-fold higher than those of bare CS membranes
PB The Royal Society of Chemistry
YR 2021
FD 2021
LK https://hdl.handle.net/10630/23884
UL https://hdl.handle.net/10630/23884
LA eng
NO Babaryk, A.A. et al. (2021) “Structural and proton conductivity studies of fibrous π-Ti2O(PO4)2·2H2O: application in chitosan-based composite membranes,” Dalton Trans., 50(22), pp. 7667–7677. doi:10.1039/D1DT00735A.
NO MAT2016-77648-R and PID2019-110249RB-I00), Junta deAndalucía (FQM-113)M. Bazaga-García thanks Junta de Andalucía for her Postdoc PAIDI grant and R. M. P. Colodrero thanks UMA Research Plan for herfinancial support.
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 20 ene 2026