Synthesis of SnS2/Carbon Quantum Dots/g-C3N4 Composite and Its Photocatalytic Property

Photocatalytic degradation of organic pollutants is considered an ideal method to solve the global environmental pollution problem. In this method, photocatalytic materials are regarded as the key factor. As an n-type photocatalytic material, graphitic carbon nitride (g-C 3 N 4 ) has attracted much attention due to its suitable bandgap, nontoxicity, and high photostability. However, g-C 3 N 4 still has defects such as insufficient visible light absorption, low specific surface area, and easy recombination of photogenerated electron–hole pairs, which lead to the poor photocatalytic performance of g-C 3 N 4 . Herein, to solve the above problems, thiourea, lemon juice, and tin chloride pentahydrate are used as precursors, while carbon quantum dots (CQDs) are used as electron mediators, and the third phase SnS 2 is introduced by a hydrothermal and ultrasonic composite method. SnS 2 /CQDs/g-C 3 N 4 composites with Z-type heterojunction are successfully prepared. The results show that the SnS 2 /CQDs/g-C 3 N 4 has a 2D0D2D structure, which effectively inhibits the recombination of photogenerated electron–hole pairs, making the material have better photocatalytic degradation activity for Rhodamine B (RhB). When the mass ratio of SnS 2 is 15%, the photocatalytic degradation efficiency of RhB by the composite reaches the best, which is 87.8%. After four cycles, the photocatalytic degradation efficiency of the 15% SnS 2 /CQDs/g-C 3 N 4 composite still remains at 82.9%.