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Photo(Electro)Chemical Oxidation of Water by the Persulfate Ion Over Aqueous Suspensions of Strontium Titanate SrTiO 3 Containing Lanthanum Chromite LaCrO 3
Author(s) -
Thewissen D. H. M. W.,
Timmer K.,
EeuwhorstReinten M.,
Tinnemans A. H. A.,
Mackor A.
Publication year - 1982
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198200033
Subject(s) - chemistry , aqueous solution , lanthanum , strontium titanate , titanate , persulfate , inorganic chemistry , ion , activation energy , analytical chemistry (journal) , oxygen , dielectric , ceramic , catalysis , biochemistry , physics , optoelectronics , organic chemistry , chromatography
The photodecomposition of the S 2 O 2‐ 8 ion to the SO 2‐ 4 ion with concomitant oxidation of water to molecular oxygen over n‐type SrTiO 3 powders mixed with LaCrO 3 (mole fraction x = 0–1), using UV light (λ > 300 nm), is considerably faster than the photochemical (UV) decomposition of S 2 O 2‐ 8 in water or the thermal reaction with or without the powder under the same conditions. The rate of oxygen formation is dependent on the temperature ( E act = 61 kJ/mol), the persulfate concentration in first order and x . At 64°C and constant [S 2 O 2‐ 8 ] a maximum rate is found at x = 0.25. The rate determining step, i.e. the transfer of an energy‐rich electron from the conduction band to the S 2 O 2‐ 8 ion, is expected to proceed faster in the case of p‐type semiconductors. In view of the reported p‐type conductivity of LaCrO 3 , which has previously been doped with the charge‐compensating Sr 11 ion, our results with the SrTiO 3 ‐ x LaCrO 3 powders are in agreement with these expectations. The sensitivity of these materials towards visible irradiation is much lower than their UV response (about 1–2%) which has also been found by determining i/V and i /λ characteristics of SrTiO 3 ‐ x LaCrO 3 single crystals under illumination in a photoelectrochemical cell.