Hetero-structure La_2O_3-modified SnO_2-Sn_3O_4 from tin anode slime for highly sensitive and ppb-Level formaldehyde detection

摘要

Tin oxides SnO2-Sn3O4 was recovered from fin anode slime via pretreatment process, and creatively applied in ultrasensitive formaldehyde detection by doping La2O3 using high energy ball milling method. Composition, morphology, structure and chemical state of the samples were characterized in detail by XRF, FT-IR, XRD, SEM, HRTEM, XPS techniques. Gas sensing results showed that 1.0 cot. % La2O3-modified SnO2-Sn3O4 revealed a prominently ultrahigh sensitivity of 117.27 towards 100 ppm formaldehyde, which was 4.9 times higher than pristine SnO2-Sn3O4, as well as rapid response/recovery speed (3 s/3 s) at 220 degrees C. Furthermore, the sensor was also found to exhibit an ultra-low detection limit of 80 ppb HCHO (S = 1.44). Outstanding selectivity, great repeatability to ppb-level HCHO and remarkable long-term stability were also displayed. The effect of doping appropriate amount of La2O3 and the possible sensing mechanism were investigated particularly. Complex hetero-structures, mixed-valence and catalytic activity of La2O3 made pivotal contributions to the improvement of HCHO sensing properties. The ultimate concept is to realize cycling economy, not only to develop a promising excellent performance formaldehyde sensor from industrial waste to increase the economic efficiency, but also to make a great contribution to environment protection and increase the value of fin slime.