Nanoflower Ni5P4 coupled with GCNQDs as Schottky junction photocatalyst for the efficient degradation of norfloxacin

[Display omitted] •Novel GCNQDs/Ni5P4 Schottky junction photocatalysts were successfully constructed.•The GCNQDs/Ni5P4 composites exhibited excellent photocatalytic activity in removing norfloxacin.•The electronic band structure of GCNQDs and Ni5P4 was studied by DFT calculation.•Enhanced mechanism of GCNQDs/Ni5P4 composites for degradation of norfloxacin was proposed. A noble metal-free photocatalyst, the porous flower spherical Ni5P4 coupled g-C3N4 quantum dots (GCNQDs) was prepared by a simple ultrasonic impregnation method for the degradation of norfloxacin in wastewater. The GCNQDs exhibit obvious quantum confining effect due to its small particle size. For Ni5P4, its large specific surface area is conducive to the adhesion of GCNQDs, so that GCNQDs/Ni5P4 composite photocatalysts have excellent photocatalytic performance. In addition, the important role of porous Ni5P4 in promoting electron-hole separation and photocatalytic performance was confirmed by experiments and density functional theory (DFT) calculations. It was found that the GCNQDs and Ni5P4 formed a Shottky junction. At the same time, the GCNQDs/Ni5P4 composite photocatalysts showed good stability in the cycle test, which made it become a kind of green, efficient and repeatable photocatalytic material. This work proposed the degradation mechanism of GCNQDs/8% Ni5P4 composite photocatalysts and the possible degradation path of norfloxacin, providing a new idea for the design of highly active composite photocatalysts.