Doping induced grain size reduction and photocatalytic performance enhancement of SrMoO₄:Bi³⁺

Graphical abstract: Photocatalytic performance of SrMoO₄ was greatly improved by Bi³⁺ doping effects, including crystalline size reduction, band gap narrowing, and lattice contraction. - Highlights: • An efficient SrMoO₄ photocatalyst was fabricated by Bi³⁺ doping under hydrothermal condition. • Bi³⁺ doping effects, including crystalline size reduction, band gap narrowing, and lattice contraction were discovered in SrMoO₄ nanomaterials. • The photocatalytic activity was great improved on account of Bi³⁺ doping effects. • Photoluminescence studies found that hydroxyl radical (·OH) is the main active species in the photocatalytic degradation process. - Abstract: Ion doping is one of the most effective ways to develop photocatalysts by creating impurity levels in the energy band structure. In this paper, novel Bi³⁺ doped SrMoO₄ (SrMoO₄:Bi³⁺) nanocrystals were prepared by a simple hydrothermal method. By systematic characterizations using x-ray diffraction, infrared spectra, UV–vis spectra, X-ray photoelectron spectroscopy and transmission electron microscopy, it is demonstrated that all the samples crystallized in a single phase of scheelite structure, and particle sizes of SrMoO₄:Bi³⁺ gradually decreased. The Bi³⁺ doped nanoparticles showed lattice contraction, and band-gap narrowing. The photocatalytic activity of the samples was measured by monitoring the degradation of methylene blue dye in an aqueous solution under UV-radiation exposure. It is found that SrMoO₄:Bi³⁺ showed excellent activity toward photodegradation of methylene blue solution under UV light irradiation compared to the pure SrMoO₄. These observations are interpreted in terms of the Bi³⁺ doping effects and the increased the surface active sites, which results in the improved the ratio of surface charge carrier transfer rate and reduced the electron–hole recombination rate. These results illustrate the potential of particle size and surface defect regulation for the construction of novel semiconductor oxide photocatalysts by ion doping.