Atomically dispersed Fe boosting elimination performance of g-C₃N₄ towards refractory sulfonic azo compounds via catalyst-contaminant interaction

Sulfonic azo compounds in wastewater can hinder the plant photosynthesis through interfering with sunlight transmission, affect the growth of aquatic organisms by destroying the ecological environment, and ultimately pose a long-term threat to human health via the food chain. In recent years, photo-self-Fenton technology has attracted much attention. This technology typically utilizes H₂O₂ in-situ generated by the photocatalyst and produces abundant active species via the self-Fenton reaction, exhibiting a good potential for the elimination of sulfonic azo contaminants.

Graphitic carbon nitride (g-C₃N₄) photocatalyst has been widely applied in the fields of pollutant degradation and H₂O₂ production. Nevertheless, its application potential has been constrained by the shortcomings of slow carrier migration and inadequate active species. The modification of g-C₃N₄ with Fe can increase the reactive active sites and accelerate the charge separation rate, as well as trigger the self-Fenton reaction.  Notably, Fe-modified g-C₃N₄ catalysts generally require the extra addition of oxidant, such as H₂O₂ and peroxymonosulfate, to obtain sufficient active species.

To date, few studies have examined how Fe-modified g-C₃N₄ may be efficient for the removal of refractory sulfonic azo compounds via catalyst-contaminant interaction without adding oxidant.

In a study published in the KeAi journal Advanced Powder Materials, a team of researchers from Jiangnan University in Wuxi, China, proposed a novel strategy to effectively eliminate refractory organics from water by Fe₁/OPCN via catalyst-contaminant interaction.

“We reported a strategy that utilizes the advanced catalyst-contaminant interaction to produce abundant multiple active species for thoroughly mineralizing sulfonic azo contaminants,” shares the study’s senior and corresponding author Jing Xu.

The researchers showed that the considerable enhancement and significant superiority of Fe₁/OPCN for removing sulfonic azo contaminants were mainly ascribed to the following aspects: (1) The modified Fe could enhance the adsorption towards sulfonic azo compounds to accelerate the mass transfer, act as the electron acceptors to promote the interfacial charge separation, and trigger the self-Fenton reaction to convert in-situ generated H₂O₂ into •OH. (2) Fe(Ⅲ) could coordinate with -N=N- to form d-π conjugation, which could attract electrons transfer to attack -N=N- bonds. Meanwhile, the inhibited charge recombination could release more free holes to oxidize sulfonic acid groups into SO₄^-•. (3) Under the cooperation of abundant multiple active species formed during the degradation reaction, sulfonic azo compounds could be completely mineralized into harmless small molecules by means of -N=N- cleavage, hydroxyl substitution, and aromatic ring opening.

“The newly designed Fe₁/OPCN composite can efficiently remove amaranth (20 μM) within 15 min under visible light with a turnover frequency of 54 h^-1, which is superior to most other photocatalysts,” adds Xu.

Contact author details: Jing Xu,School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China, Email: xujing823@jiangnan.edu.cn

Funder: This work was supported by the Natural Science Foundation of Jiangsu Province (BK20221541), National Natural Science Foundation of China (21707052), Jiangsu Agriculture Science and Technology Innovation Fund (CX(20)3108).

Conflict of interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

See the article: by Puying Liang, et al. Atomically dispersed Fe boosting elimination performance of g-C₃N₄ towards refractory sulfonic azo compounds via catalyst-contaminant interaction. Advanced Powder Materials, Volume 4, 2025, pages 100251. https://doi.org/10.1016/j.apmate.2024.100251