Construction of PDDA functionalized black phosphorus nanosheets/BiOI Z-scheme photocatalyst with enhanced visible light photocatalytic activity.

The use of black phosphorus (BP) nanosheets has attracted much attention in the area of photocatalysis owing to the thickness-tunable bandgap and high carrier mobility. In order to improve the stability of BP nanosheets, poly dimethyldiallyl ammonium chloride (PDDA) is used to passivate the BP nanosheets and change its surface properties. The present study concerns the development of a facile electrostatic assembly method for the construction of a Z-scheme system consisting of PDDA-functionalized BP nanosheets and layered BiOI in order to enhance visible light adsorption and promote electron-hole separation. The morphology, structure and photoelectrochemical properties of the composites are thoroughly characterized and the photocatalytic performances of all the samples were assessed under visible light irradiation. The 5-F-BP/BiOI exhibits excellent photocatalytic activity with removal efficiencies of 97.6% and 90.0% for methylene blue (MB) and tetracycline (TC), respectively. Superoxide radicals (·O) were found to be the main organic decomposition products according to species trapping experiments. The photocatalyst presents favorable stability after three catalytic cycles. This study provides new insights into the design of highly efficient Z-scheme photocatalysts based on functionalized BP nanosheets in order to meet environmental demands.