0D/2D Z-Scheme Heterojunctions of Bismuth Tantalate Quantum Dots/Ultrathin g-C3N4 Nanosheets for Highly Efficient Visible Light Photocatalytic Degradation of Antibiotics.

Constructing 0D/2D Z-scheme photocatalysts is a great promising path to improve photocatalytic activity by  efficiently enhancing charge separation. Herein, we fabricated a visible-light-responsive Bi3TaO7 quantum dots (QDs)/g-C3N4 nanosheets (NSs) 0D/2D Z-scheme composite via a facile ultrasound method, and Bi3TaO7 QDs could be interspersed on the surface of g-C3N4 NSs uniformly. Furthermore, the strong interaction between Bi3TaO7 QDs and g-C3N4 NSs disturbed the CN heterocycles by forming C═O bonds between C atoms of the N-(C)3 group and O atoms of the Ta-O bond. The optimum composite with 20 wt % g-C3N4 NSs showed the superior photocatalytic activity for degradation of ciprofloxacin (CIP) over the composites prepared by mechanical mixing and solid-state methods, the photocatalytic efficiency of which were 4 and 12.2 times higher than those of bare Bi3TaO7 and g-C3N4. Photoluminescence (PL), time-resolved transient PL decay spectra, and photocurrent together verify that the photogenerated hole-electron pairs in this 0D/2D Z-scheme composite have been effectively separated. The enhanced photocatalytic activity of as-synthesized photocatalysts could be attributed to the synergistic effect of efficient Z-scheme charge separation, highly dispersed 0D Bi3TaO7 nanocrystals, coordinating sites of 2D g-C3N4 NSs and the strong coupling between them. This study might pave the way toward designing novel visible-light-induced 0D/2D photocatalyst systems for highly efficient degradation of antibiotics.