Photocatalytic activity of a Bi-based oxychloride Bi₄NbO₈Cl

The Bi-based oxychloride Bi₄NbO₈Cl with a layered structure was studied as a novel efficient photocatalyst. The compound prepared by a solid state reaction method has a band gap of 2.38 eV. It possesses an excellent visible-light-response ability. The visible-light-driven photocatalytic activities for degrading methyl orange (MO) over different catalysts follow the decreasing order of Bi₄NbO₈Cl > Bi₃O₄Cl > anatase TiO₂, different from the order found under UV light illumination (Bi₃O₄Cl > anatase TiO₂ > Bi₄NbO₈Cl). The dispersion of Pt over Bi₄NbO₈Cl leads to an obvious increase in photocatalytic performance, to about 1.5 times higher. The polarizing fields in NbO₆ and BiO₈ local structures, as well as the internal electrical fields between [Bi₂O₂] and [Cl] slabs, are considered to be useful for the efficient separation of electron-hole pairs upon photoexcitation.