Single-atom Ag confined with nitrogen coordination in porous tubular g-C3N4 as fenton-like photocatalyst for solar-powered water purification

Efficient and sustainable water purification is the key to safe drinking water. Single-atom Fenton-like processes have attracted widespread attention because of high catalytic efficiency and environmental friendliness. Herein, Ag single-atom catalyst (SACs) in porous tubular carbon nitride (SAAg@PTCN) was successfully synthesized by one-step thermal polymerization method using silver tricyanomethanide (AgTCM), urea and melamine, which was based on the molecular structural similarity between AgTCM and g-C₃N₄. The addition of single-atom Ag promoted photocarrier separation, inhibited recombination, expanded light absorption range, reduced potential barrier and improved electron transfer ability in visible light and peroxymonosulfate (Vis-PMS) system, which was beneficial to improve the degradation efficiency of carbamazepine (CBZ). The CBZ could be degraded 98.2% in 45 min and degradation rate constant in SAAg@PTCN/Vis-PMS system (0.066 min⁻¹) was notably higher compared to PTCN/Vis-PMS (0.0219 min⁻¹). Significantly, Ag⁺ concentration after photocatalytic degradation remained at 0.07 mg/L and the degradation efficiency could still reach 100% after five reactions, which indicated that SAAg@PTCN/Vis-PMS system had strong stability and recyclability. Furthermore, non-free radicals (¹O₂ and h⁺) and free radicals (O₂^•−, HO^• and SO₄^•−) were the primary reactive oxygen species (ROS), which was beneficial to adapt to a wide range of pH and degrade a variety of pollutants in actual water bodies. The solar powered Fenton-like water purification device had achieved efficient co-degradation performance for EPs and microcystis aeruginosa, which verified the practical application potential of SAAg@PTCN. SAAg@PTCN held significant promise as a sustainable and viable solution for efficient water purification.