Fe-doped g-C3N4 synthesized by supramolecular preorganization for enhanced photo-Fenton activity

Abstract

The photo-Fenton process, with a synergistic effect of Fenton oxidation and photocatalysis, is a promising technique for the removal of refractory organic pollutants. However, the rapid recombination of photogenerated charge carriers results in less electrons for Fe(III)/Fe(II) cycle and later generation of hydroxyl radicals. In this work, Fe-doped graphite carbon nitride with a thin nanosheet structure (∼5 nm thickness) was prepared using the supramolecular preorganization method (Fe/CNSP), which effectively suppresses the recombination of photogenerated charges compared with that of Fe-doped bulk carbon nitride (Fe/BCN), resulting in an obviously improved photo-Fenton performance by increasing the electron gain at the Fe sites and the speed of the reduction of Fe(III) to Fe(II). The heterogeneous photo-Fenton activity of Fe/CNSP displays a 6.5 times higher kinetic constant for carbamazepine degradation than that of Fe/BCN, and universal effectiveness toward other organic pollutants, namely phenol, sulfamethoxazole, bisphenol A, and 2,4-dichlorophenol, with TOC removals between 37.4% and 91.3% in 150 min. OH, O2−, e−, h+, and 1O2 contribute to the degradation of organic pollutants. Fe/CNSP was proven to be stable and reusable in cyclic experiments. The analysis of the intermediate toxicity demonstrated that the Fe/CNSP photo-Fenton system effectively reduced the toxicity of carbamazepine. This study offers a simple, highly reproducible method for developing efficient heterogeneous photo-Fenton catalysts.