Internal Electric-Field-Driven CoAl-LDH Coupled N-Rich Carbon Nitride of C3N5 for Improved Photocatalytic Performance

Abstract

Preparing photocatalysts with excellent performance to degrade organic pollutants in water is still a great challenge. Herein, we prepared CoAl-layered double hydroxide (LDH) coupled N-rich carbon nitride of C3N5 materials to investigate the feasibility of preparing materials for photocatalytic treatment of organic pollutants under natural water bodies. After 120 min of light exposure, the CoAl-LDH/C3N5 (CCN-100) composite showed optimal photocatalytic degradation performance, in which the degradation efficiency reached 94.02% in pure water and 91.85% in Xiangjiang water. Three possible photocatalytic degradation pathways of tetracycline were analyzed by liquid chromatography with tandem mass spectrometry. The toxicity of the intermediates was assessed by toxicity assessment software. The results showed that the toxicity of the intermediates was greatly reduced. We analyzed the formation of the internal electric field and the direction of charge migration in the CoAl-LDH/C3N5 heterojunction by the difference in the work function and the energy band structure of CoAl-LDH and C3N5. According to various characterization analysis and experimental results, the internal electric field formed between CoAl-LDH and C3N5 accelerates the charge transfer and the rapid separation of photogenerated electron holes thus improving the photocatalytic degradation performance. This study provides new insights into the effective removal of organic pollutants from water through the formation of an internal electric field in CoAl-LDH/C3N5 heterojunction.