A novel open–framework spheniscidite photocatalyst with excellent visible light photocatalytic activity: Silver sensitization effect and DFT study

Abstract

We report a novel silver modified spheniscidite (SPH–Ag) visible light responsive photocatalyst with open–framework structure. The SPH–Ag photocatalyst was firstly synthesized by one step hydrothermal method. Meanwhile, the contribution of silver sensitization to the visible light photocatalytic property of SPH–Ag was confirmed by characterization results and DFT calculation. Ag+ is demonstrated to enter into the spheniscidite cavities and replace one NH4+ per unit cell without destroying the structure. Noteworthy, compared to SPH, the pure phase SPH–Ag catalyst equipped with larger specific surface area, broader visible light response region, stronger oxidizing ability and lower recombination rate of electrons and holes. Meanwhile, the valence electrons are rearranged and the unoccupied Ag 5s orbital hybridizes with Fe 3d and O 2p orbitals at valance band, which greatly improves the SPH–Ag’s ability of gaining electrons and the separation of photo generated charge carriers. As expected, the SPH–Ag catalyst exhibited enhanced photocatalytic activity for ARG degradation under visible light irradiation, which is mainly attributed to the generation of h+ and O2− species. Furthermore, its photocatalytic property was highly maintained as well as its structure and surface chemical properties after five recycles. This work may provide insight into the design of new–type Ag–based photocatalysts and their photocatalytic mechanism.