Perovskite-like LaxSr2-xTi1−x/2Cux/2O4 (x = 0.2, 0.3, 0.5) oxides with the K2NiF4-type structure active in visible light range: new members of the photocatalyst family

Chupakhina, T. I.; Eremina, R. M.; Gyrdasova, O. I.; Yanchenko, M. Yu.; Buldakova, L. Yu.; Yatsyk, I. V.; Gavrilova, T. P; Deeva, Yu. A.; Sukhanov, A. A.; Baklanova, I. V.; Uporova, A. M.; Chupakhina, T. I.; Eremina, R. M.; Gyrdasova, O. I.; Yanchenko, M. Yu.; Buldakova, L. Yu.; Yatsyk, I. V.; Gavrilova, T. P; Deeva, Yu. A.; Sukhanov, A. A.; Baklanova, I. V.; Uporova, A. M.

doi:2024.61.4.623

J. Korean Ceram. Soc. > Volume 61(4); 2024 > Article

Original Article

Journal of the Korean Ceramic Society 2024;61(4): 623-635.
doi: https://doi.org/10.1007/s43207-024-00382-0

Perovskite-like La_xSr_2-xTi_1−x/2Cu_x/2O₄ (x = 0.2, 0.3, 0.5) oxides with the K₂NiF₄-type structure active in visible light range: new members of the photocatalyst family

T. I. Chupakhina¹, R. M. Eremina², O. I. Gyrdasova¹, M. Yu. Yanchenko¹, L. Yu. Buldakova¹, I. V. Yatsyk², T. P Gavrilova², Yu. A. Deeva¹, A. A. Sukhanov², I. V. Baklanova¹, A. M. Uporova¹

¹Ural Branch of the Russian Academy of Sciences, Institute of Solid State Chemistry, Ekaterinburg, 620990, Russia
²FRC Kazan Scientific Center of RAS, Zavoisky Physical-Technical Institute, Kazan, 420029, Russia

Correspondence

T. I. Chupakhina ,Email: chupakhina@yandex.ru

Received: August 18, 2023; Revised: December 25, 2023 Accepted: February 11, 2024. Published online: March 26, 2024.

ABSTRACT

A layered perovskite-like oxides La_xSr_2-xTi_1−x/2Cu_x/2O₄ (x = 0.2, 0.3, 0.5) with a K₂NiF₄-type structure were obtained. The introduction of copper into the titanium sublattice reduces the band gap. Copper in these materials serve as a photoactivity regulator and is presented in two oxidation states in accordance with optical, voltammetric and EPR data. La_xSr_2-xTi_1−x/2Cu_x/2O₄ (x = 0.2) exhibits the greatest photoactivity in the oxidation of phenolic compounds and As(III) under the influence of UV and blue light; with increasing degree of substitution x, the photoactivity of La_xSr_2-xTi_1−x/2Cu_x/2O₄ decreases. This is explained by the formation of a magnetic polaron, which is observed in La_xSr_2-xTi_1−x/2Cu_x/2O₄ (x = 0.5) in the temperature range from 50 to 200 K and is proven by ESR method. The expansion of the spectral range of La_xSr_2-xTi_1−x/2Cu_x/2O₄ to the visible region is explained by the formation of acceptor levels (Cu²⁺ + e^- → Cu⁺ /Cu⁺ + h⁺ → Cu²⁺) in the band gap of Sr₂TiO₄, which increases the efficiency of separation of photogenerated electron–hole pairs. The presence of Cu (I) в La_xSr_2-xTi_1−x/2Cu_x/2O₄ enhance photoactivity through the formation of active superoxygen radical on its surface (Cu⁺ + O_2(ad) → Cu²⁺ + ᆞO₂^-).

Key words: Perovskites · Photocatalysis · Precursor synthesis · Voltammetry