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 SnO 2 material (S-SnO 2 ) 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-SnO 2, the as-prepared Ag/Ag 2 S-doped S-SnO 2 (Ag/Ag 2 S/S-SnO 2 ) showed an excellent sensing performance toward SO 2 . 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 N 2 adsorption–desorption. The recovered S-SnO 2 dispersed by titanate coupling agents (CT-201) showed enhanced particle dispersion and an enlarged active surface area and exhibited a high response toward SO 2 . Ag/Ag 2 S modification of the dispersed S-SnO 2 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 SO 2 dissociation by further reacting between SO 2 oxidation products and Ag 2 S. This work demonstrated the enhancement mechanism of the reaction between multiple valence sulfides on SO 2 -sensitive properties of SnO 2 -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.