Ag/Ag₂S Nanoparticle-Induced Sensitization of Recovered Sulfur-Doped SnO₂ Nanoparticles for SO₂ Detection

Sulfur dioxide is one of the most hazardous and toxic air pollutants. Herein, S-doped SnO2 material (S-SnO2) was successfully recovered from tin sludge that is an important secondary tin resources with a tremendous output and high tin oxide content. After dispersion and Ag modification of the recovered S-SnO2, the as-prepared Ag/Ag2S-doped S-SnO2 (Ag/Ag2S/S-SnO2) showed an excellent sensing performance toward SO2. The morphology, structure, and surface state of the as-prepared materials were performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), photoluminescence (PL), and N2 adsorption–desorption. The recovered S-SnO2 dispersed by titanate coupling agents (CT-201) showed enhanced particle dispersion and an enlarged active surface area and exhibited a high response toward SO2. Ag/Ag2S modification of the dispersed S-SnO2 obtained a markedly increased response of 10.1 and a lower operating temperature of 180 °C by increasing the amount of surface oxygen vacancies and by facilitating SO2 dissociation by further reacting between SO2 oxidation products and Ag2S. This work demonstrated the enhancement mechanism of the reaction between multiple valence sulfides on SO2-sensitive properties of SnO2-based catalysts. Furthermore, this work realized high-value-added recovery of a secondary tin resource and contributed to the alleviation of the scarcity of tin resources and reduction in the burden on the environment.