Synthesis of porous pinecone-like structure via facile carbon quantum dots modulation: A promising approach for improving the photocatalytic capability of carbon nitride

The modification of photocatalyst morphology and structure have significant influence on their photocatalytic activity. Herein, a novel porous pinecone-like structure carbon quantum dots modified supramolecular self-assembly carbon nitride (N-CQDs/MCNx) with controllable morphology was synthesized by adding carbon quantum dots into Melamine-Cyanuric acid self-assembly system. The characterizations of physicochemical properties demonstrate that the carbon quantum dots affect the hydrogen bond strength between supramolecular self-assembled aggregates by carrying a large number of oxygen-containing groups, resulting in different changes in the final morphology of photocatalysts. In addition, photocatalysts exhibit excellent degradation rate of tetracycline hydrochloride (TC-HCl) via increasing reaction active sites, enhancing light absorption , improving photogenerated carrier migration rate and inhibiting photogenerated electron-hole recombination. Under the optimum addition of carbon quantum dots, N-CQDs/MCN1 degraded 89% of TC-HCl within 120 min, which was 72% and 49% higher than that of pure carbon nitride (17%) and supramolecular self-assembled carbon nitride (40%), respectively. The trapping experiments further proved that superoxide radicals and holes are the main active species during the photocatalytic degradation of TC-HCl. This research provides a new strategy for the regulation of photocatalyst morphology.