Iron single atoms anchored on ultrathin carbon nitride photocatalyst for visible light-driven water decontamination

Graphitic carbon nitride has gained considerable attention as a visible-light photocatalyst. However, its photocatalytic efficiency is restricted by its limited capacity for absorbing visible light and swift recombination of charge carriers. To overcome this bottleneck, we fabricated an atomic Fe-dispersed ultrathin carbon nitride (Fe-UTCN) photocatalyst via one-step thermal polymerization. Fe-UTCN showed high efficiency in the photodegradation of acetaminophen (APAP), achieving >90% elimination within 60-min visible light irradiation. The anchoring of Fe atoms improved the photocatalytic activity of UTCN by narrowing the bandgap from 2.50eV to 2.33eV and suppressing radiative recombination. Calculations by density functional theory revealed that the Fe–N4 sites (adsorption energy of −3.10eV) were preferred over the UTCN sites (adsorption energy of −0.18eV) for the adsorption of oxygen and the subsequent formation of O2•−, the dominant reactive species in the degradation of APAP. Notably, the Fe-UTCN catalyst exhibited good stability after five successive runs and was applicable to complex water matrices. Therefore, Fe-UTCN, a noble-metal-free photocatalyst, is a promising candidate for visible light-driven water decontamination. Environmental Implication Photocatalysis has been proposed as a sustainable technology for water decontamination. However, there is a lack of advanced photocatalysts that can efficiently convert solar energy into chemical energy. In this work, we anchored single atoms of Fe on ultrathin carbon nitride (Fe-UTCN) to create an effective photocatalyst, which enables >90% removal of acetaminophen at a rate of 0.0363min-1. The Fe-UTCN exhibited good stability over five successive runs, was applicable to a wide range of pH environments (3.0–9.0), and functioned efficiently in natural water samples with removal efficiencies greater than 75%. This work demonstrates the feasibility of using a noble metal-free photocatalyst for effectively removing refractory pollutants from water bodies under visible-light irradiation.