Influence of oxygen vacancy defects and cobalt doping on optical, electronic and photocatalytic properties of ultrafine SnO2-δ nanocrystals

• Main Authors: Zorana D. Dohčević-Mitrović, Vinicius D. Araújo, Marko Radović, Sonja Aškrabić, Guilherme R. Costa, Maria Ines B. Bernardi, Dejan M. Djokić, Bojan Stojadinović, Marko G. Nikolić
• Format: Article
• Language: English
• Published: University of Novi Sad 2020-05-01
• Series: Processing and Application of Ceramics
• Subjects: sno2 nanopowders; wet-chemical synthesis; defects; optical properties; photocatalysis
• Online Access: http://www.tf.uns.ac.rs/publikacije/PAC/pdf/PAC%2048%2002.pdf
• ISSN: 1820-6131; 2406-1034

Ultrafine pure and cobalt doped SnO2-δ nanocrystals (Sn1-xCoxO2-δ, 0 ≤ x ≤ 0.05) were synthesized by microwave-assisted hydrothermal method. The as-prepared nanocrystals have single phase tetragonal rutile structure. With increase of Co content (x > 0.01), Co entered into SnO2 lattice in mixed Co2+/Co3+ state. Pronounced blue shift of the band gap with cobalt doping originated from the combined effect of quantum confinement and Burnstain-Moss shift. Raman and photoluminescence study revealed oxygen deficient structure of SnO2-δ for which the prevalent defects are in the form of in-plane oxygen vacancies. Co-doping induced decrease of in-plane oxygen vacancy concentration and luminescence quenching. SnO2-δ exhibited significantly better photocatalytic activity under UV light irradiation, than Co-doped samples due to better UV light absorption and increased concentration of in-plane oxygen vacancies which, as shallow donors, enable better electron-hole separation and faster charge transport.