A visible-light driven novel layered perovskite oxyhalide Bi4MO8X (M = Nb, Ta; X = Cl, Br) constructed using BiOX (X = Cl, Br) for enhanced photocatalytic hydrogen evolution

A novel visible-light responsive layered perovskite photocatalyst Bi4MO8X (M = Nb, Ta; X = Cl, Br) has been successfully constructed using BiOX (X = Cl, Br) via a solid state method. The as-prepared samples were characterized by XRD, SEM, HRTEM, EDS, element mapping, XPS and UV-vis spectra to determine the structures, morphologies and optical properties. Photocatalytic activities were conducted under simulated sunlight as well as visible light and evaluated by the efficiency of hydrogen evolution. Among these photo-catalysts, the photocatalytic capability of hydrogen generation for Bi4NbO8X was better than that of Bi4TaO8X (X = Cl, Br), while Bi4NbO8Br showed the best performance for photocatalytic hydrogen production. Moreover, these photocatalysts exhibited excellent activity for hydrogen generation when glycerol was utilized as a sacrificial agent, which could be assigned to its low standard oxidation potential and the number of alpha-OH groups. Furthermore, we demonstrated that the structural properties of Bi4NbO8Br were beneficial for the mobility of photocarriers. The reason for this can be ascribed to the [Bi2O2](2+) structures with lower twisting degree, as evidenced by the Raman spectra analysis.