Relationship between interlayer hydration and photocatalytic water splitting of A'{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O (A'=K and Li)
- Department of Nano Science and Technology, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)
Partial replacement of alkaline metals in anhydrous KCa{sub 2}Ta{sub 3}O{sub 10} and LiCa{sub 2}Ta{sub 3}O{sub 10} was studied to control interlayer hydration and photocatalytic activity for water splitting under UV irradiation. A'{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O (A'=K and Li) samples were synthesized by ion exchange of CsCa{sub 2}Ta{sub 3}O{sub 10} in mixed molten nitrates at 400 deg. C. In K{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O, two phases with the orthorhombic (C222) and tetragonal (I4/mmm) structures were formed at x{<=}0.7 and x{>=}0.5, respectively. Upon replacement by Na{sup +} having a larger enthalpy of hydration ({delta}H{sub h}{sup 0}), the interlayer hydration occurred at x{>=}0.3 and the hydration number (n) was increased monotonically with an increase of x. Li{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O showed a similar hydration behavior, but the phase was changed from I4/mmm (x<0.5, n{approx}0) via P4/mmm (x{approx}0.5, n{approx}1) to I4/mmm (x{approx}1.0, n{approx}2). The photocatalytic activities of these systems after loading 0.5 wt% Ni were quite different each other. K{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O exhibited the activity increasing in consistent with n, whereas Li{sub 1-x}Na{sub x}Ca{sub 2}Ta{sub 3}O{sub 10}.nH{sub 2}O exhibited the activity maximum at x=0.77, where the rates of H{sub 2}/O{sub 2} evolution were nearly doubled compared with those for end-member compositions (x=0 and 1). - Graphical abstract: The partial substitution of Na in the interlayer of anhydrous-layered perovskite has been found as useful structural modification toward highly active hydrated photocatalysts.
- OSTI ID:
- 21128327
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 6; Other Information: DOI: 10.1016/j.jssc.2008.03.020; PII: S0022-4596(08)00163-1; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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