Terbium-modified graphitic carbon nitride triggered Fe^IVO²⁺-mediated mild chemiluminescence for sulfite detection in atmospheric aerosols

The direct and precise detection of sulfite (SO₃^2-) is of paramount significance in the field of environmental monitoring. To overcome the limitations of conventional chemiluminescence (CL) assay for SO₃^2- detection, including reliance on strong oxidants in acidic media, poor selectivity, and complex matrix interference, this study developed a mild CL sensing platform, by leveraging terbium-modified graphitic carbon nitride nanoparticles (Tb-CNNPs) to trigger a ferryl ion-mediated Fenton reaction, achieving highly selective, interference-resistant, and sensitive detection of SO₃^2- in atmospheric aerosols. Specifically, Tb-CNNPs with rich nitrogen defects were synthesized via a solvothermal method. Acting as both a catalyst and a luminophore, Tb-CNNPs initiated SO₃^2- CL emission in the presence of Fenton system under neutral conditions. Mechanistic investigations revealed that Tb-CNNPs interact specifically with SO₃^2- to form more active sites, which accelerate the Fe²⁺/Fe³⁺ redox cycle and boost ¹O₂ generation in the Fenton reaction. The strong CL emission arises from chemiluminescence resonance energy transfer (CRET) between Tb-CNNPs and (¹O₂)₂*. Notably, the key reactive intermediate during the CL reaction under neutral conditions is the ferryl ion rather than the traditional hydroxyl radical, which engages in a specific oxygen atom transfer reaction with SO₃^2-, accounting for the exceptional selectivity and anti-interference capability of SO₃^2- detection. Based on these findings, the Tb-CNNPs/SO₃^2-/Fenton system was successfully applied to the determination of SO₃^2- in atmospheric aerosol samples. This work provides a reliable and efficient analytical strategy for the accurate detection of SO₃^2- in neutral media under complex environmental conditions.