Heterostructured BiOI@La(OH) 3 nanorods with enhanced visible light photocatalytic NO removal

Heterostructured BiOI@La(OH)3 nanorod photocatalysts were prepared by a facile chemical impregnation method. The enhanced visible light absorption and charge carrier separation can be simultaneously realized after the introduction of BiOI particles into La(OH)3 nanorods. The BiOI@La(OH)3 composites were applied for visible light photocatalytic oxidization of NO in air and exhibited an enhanced activity compared with BiOI and pure La(OH)3 nanorods. The results show that the energy levels between the La(OH)3 and BiOI phases matched well with each other, thus forming a heterojunctioned BiOI@La(OH)3 structure. This band structure matching could promote the separation and transfer of photoinduced electron-hole pairs at the interface, resulting in enhanced photocatalytic performance under visible light irradiation. The photocatalytic performance of BiOI@La(OH)3 is shown to be dependent on the mass ratio of BiOI to La(OH)3. The highest photocatalytic performance can be achieved when the mass ratio of BiOI to La(OH)3 is controlled at 1.5. A further increase of the mass ratio of BiOI weakened the redox abilities of the photogenerated charge carriers. A new photocatalytic mechanism for BiOI@La(OH)3 heterostructures is proposed, which is directly related to the efficient separation of photogenerated charge carriers by the heterojunction. Importantly, the as-prepared BiOI@La(OH)3 heterostructures exhibited a high photochemical stability after multiple reaction runs. Our findings demonstrate that BiOI is an effective component for the formation of a heterostructure with the properties of a wide bandgap semiconductor, which is of great importance for extending the light absorption and photocatalytic activity of wide bandgap semiconductors into visible light region.