Fabrication of novel p-n heterojunction BiOI/La2Ti2O7 composite photocatalysts for enhanced photocatalytic performance under visible light irradiation.

In this paper, novel p-n type heterojunction BiOI/La2Ti2O7 nanocomposites were synthesized via a simple method for obtaining visible light activated photocatalysts. The crystal phases and crystallinity of the prepared samples were analyzed by X-ray diffraction (XRD). The morphologies of the BiOI/La2Ti2O7 composites were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The elemental composition and states were analyzed by X-ray photoelectron spectroscopy (XPS). Results showed that the obtained composites were constructed by 2D BiOI and La2Ti2O7 nanosheets. Besides, UV-vis diffuse reflectance spectrometry (DRS) indicated that BiOI/La2Ti2O7 composites possessed better visible light absorptive properties than pure La2Ti2O7. The photocatalytic activity was evaluated by the degradation of Rhodamine B (RhB), dye X-3B, methyl orange (MO) and a colorless antibiotic agent, ciprofloxacin (CIP), under visible light irradiation. Results showed that BiOI/La2Ti2O7 composites exhibited much higher activity than the corresponding single components. First of all, the enhanced activity can be ascribed to the improved visible light harvesting. Secondly, the results of photo-induced current and photoluminescence spectroscopy illustrated that the enhanced performance can also be attributed to the efficient transfer and separation of photoinduced charges, which resulted from the formed p-n heterojunctions between BiOI and La2Ti2O7. It can be expected that this novel 2D-2D p-n heterostructured photocatalyst would be a promising candidate for environmental remediation.