Constructing porous intramolecular donor–acceptor integrated carbon nitride doped with m-aminophenol for boosting photocatalytic degradation and hydrogen evolution activity

Abstract

Graphitic carbon nitride (CN) has been recognized as a promising photocatalyst for energy production and environmental remediation, although a high carrier recombination rate, low active site exposure and inadequate visible-light utilization prominently restrict its photocatalytic activity. Herein, a porous intramolecular D–A integrated CN for boosting photocatalytic activity under visible light was constructed via thermal melting followed by thermally induced copolymerization of m-aminophenol with urea. The optimal sample (CN₃₀) possesses a porous nano-multilayer structure and superhydrophilicity, and enhanced crystallinity, specific surface area, visible light harvesting, and exciton separation and carrier migration efficiency. The hydrogen evolution rate and photodegradation rate of CN₃₀ are 1121 μmol h⁻¹ g⁻¹ and 76.9% (20 mg of CN₃₀ degrades 40 mg L⁻¹ tetracycline), respectively, which are 2.73 and 5.3 times those of pristine CN, as well as being significantly higher than those of CN_Aniline and CN_Phenol. DFT calculations confirm that electrons in CN₃₀ are accumulated on the tri-s-triazine ring which serves as an electron acceptor, and the m-aminophenol unit serves as an electron donor to promote faster electron transfer to the CN skeleton. ESR and free radical capture experiments confirm that ¹O₂ and ˙O₂⁻ are the dominant active species. And LC-MS clarifies the intermediates and pathways in the process of TC photodegradation. This research provides a new reference for boosting the activity of integrated CN photocatalytic materials for solar-to-chemical energy conversion.