(Sr0.6Bi0.305)2Bi2O7 as a new visible-light-responsive photocatalyst: An experimental and theoretical study

The pyrochlore-type (Sr_0.6Bi_0.305)₂Bi₂O₇ containing Bi³⁺ and Bi⁵⁺ mixed valent states was first investigated as a new photocatalytic material in this work and successfully synthesized by a facile hydrothermal method. The phase structure, morphology, microstructure, elemental composition, and optical properties of samples were characterized in details. The experimental measurements combining with the first-principles calculations show that (Sr_0.6Bi_0.305)₂Bi₂O₇ is a n-type semiconductor with a band gap of 1.25 eV. The photocatalytic activity of (Sr_0.6Bi_0.305)₂Bi₂O₇ was evaluated by the degradation of various organic dyes. Our results show that (Sr_0.6Bi_0.305)₂Bi₂O₇ exhibits high photocatalytic efficiency and stability under visible light irradiation. The calculated electronic density of states indicates that Bi and O atoms close to the Sr vacancy probably possess higher activity and are helpful for its photocatalytic performance.