Metal-Free Carbon Quantum Dots Implant Graphitic Carbon Nitride: Enhanced Photocatalytic Dye Wastewater Purification with Simultaneous Hydrogen Production.

ABSTRACT: The use of photocatalysts to purify wastewater and simultaneously convert solar energy into clean hydrogen energy is of considerable significance in environmental science. However, it is still a challenge due to their relatively high costs, low efficiencies, and poor stabilities. In this study, a metal-free carbon quantum dots (CQDs) modified graphitic carbon nitride photocatalyst (CCN) was synthesized by a facile method. The characterization and theoretical calculation results reveal that the incorporation of CQDs into the g-C3N4 matrix significantly improves the charge transfer and separation efficiency, exhibits a redshift of absorption edge, narrows the bandgap, and prevents the recombination of photoexcited carriers. The hydrogen production and simultaneous degradation of methylene blue (MB) or rhodamine B (RhB) in simulated wastewaters were further tested. In the simulated wastewater, the CCN catalyst showed enhanced photodegradation efficiency, accompanied with the increased hydrogen evolution rate (1291 µmol·h-1·g-1). The internal electrical field between the g-C3N4 and the CQDs is the main reason for the spatial separation of photoexcited electron-hole pairs. Overall, this work could offer a new protocol for the design of highly efficient photocatalysts for dye wastewater purification with simultaneous hydrogen production.

SUBMITTER: Zhang L 

PROVIDER: S-EPMC7036787 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature