The silicon active sites driven by oxygen vacancies in iron silicate for activating peroxymonosulfate

Most metal sites and some non-metallic sites such as carbon and nitrogen are usually considered to be traditional active sites during peroxymonosulfate (PMS) activation. However, as an important non-metallic element, the actual role of silicon (Si) in PMS activation still remains unclear. In this work, taking iron silicate (FeSi) as an example, the role of the Si region in PMS activation was clearly revealed. The experiments and density functional theory (DFT) calculation results showed that besides the traditional Fe sites, the Si also played a non-negligible role during PMS activation. In FeSi containing oxygen vacancies (Ovac), Fe-Si was the active site instead of Fe-Fe. The Bard charge results implied that the presence of Ovac tuned the electronic properties of FeSi, making the Si participate in PMS activation. This work deepened understanding of the role of Si in silicates for PMS activation and provided a theoretical basis for the development of excellent Si-based catalysts.