Hydrogen bond interactions within OH-CQDs/fiber-like carbon nitride for enhanced photodegradation and hydrogen evolution
Jinqiang Zhang, Edith Cowan UniversityFollow
Shuaijun Wang, Edith Cowan University
Applied Surface Science
School of Engineering
This work was financially supported by the National Science and Technology Major Project (No. 2016ZX05040003)
Graphitic carbon nitride (g-C3N4) possess great potential applications in photocatalytic wastewater purification and hydrogen production. However, its activity is moderate because of the sluggish electron transfer and insufficient light absorption. Here, a series of hydroxyl carbon quantum dots modified with fiber-like carbon nitride composites (OH-CQDs/CNF) were synthesized by a solvothermal approach to enhance the photocatalytic activity. Compared to g-C3N4, the prepared OH-CQDs/CNF exhibited significantly improved visible light absorption (UV-VIS), low recombination electron-hole pairs (PL), and dramatically enhanced conductivity (EIS). Therefore, the optimized OH-CQDs/CNF-4 composite (derived from 4 mL OH-CQDs) displayed excellent photodegradation activity, and its rate constant for tetracycline degradation was 11.3 times higher than that in the presence of g-C3N4, even higher than some noble metal or metal oxides modified g-C3N4. In addition, OH-CQDs/CNF-4 rendered around 4 times H2 evolution rate than CNF, mainly because the OH-CQDs were highly dispersed on the CNF surface and formed an intact interface through hydrogen bond interactions. Quenching experiments and ESR results indicated that ·O2− and h+ were the main free radicals generated during TC degradation. This study provides guidance for the design of hydrogen bonding-based metal-free photocatalysts for wastewater purification and hydrogen evolution.