Construction of high-performance g-C3N4-based photo-Fenton catalysts by ferrate-induced defect engineering†
Abstract
A photo-Fenton system based on the polymer semiconductor g-C3N4 is an important practical visible-light-driven advanced oxidation catalyst with high efficiency and low cost. However, the lack of primary photocatalytic active sites on g-C3N4 and the difficulty in the uniform loading of Fenton-like iron components on g-C3N4 decrease the performance and stability of g-C3N4-based photo-Fenton catalysts. Surface defect engineering, an effective strategy to enhance the photocatalytic active sites of g-C3N4, can improve the performances of g-C3N4-based photo-Fenton systems. In this work, a highly-efficient photo-Fenton catalyst with a porous structure and cyano group defects was successfully prepared by a simple one-step thermal polymerization using ferrate as a critical iron source and defect control additive. A heterogeneous photocatalysis-Fenton tetracycline degradation experiment was conducted with the addition of H2O2 under visible light irradiation. The as-developed CN–Fe 0.10 exhibits an 8.3 times higher removal rate than single photocatalysts, and high recycling stability. Systematic material and electrochemical characterization studies demonstrated that the ferrate-induced photo-Fenton system realized ideal coordination of the Fe–Nx coupling structure and multiple defects (intercalation defect, mesoporous defect, cyano group defect), and thus improved the separation of photogenerated charge carriers and sped up the interfacial reaction. These findings provide a new idea for smart and accurate regulation of g-C3N4 defects and g-C3N4-based complex catalysis systems using novel green reagents.