Perovskite La0.75Sr0.25Cr0.5Mn0.5O3−δ sensitized SnO2 fiber-in-tube scaffold: highly selective and sensitive formaldehyde sensing

Abstract

In this work, highly porous SnO₂ fiber-in-tubes (FITs), which are functionalized with perovskite La_0.75Sr_0.25Cr_0.5Mn_0.5O_3−δ (LSCM) particles as a chemical sensitizer, are used as a superior formaldehyde (CH₂O) sensing layer. LSCM-loaded as-spun Sn precursor/polymer composite fibers are rapidly calcined to create a porous FIT SnO₂ structure with high surface area. Such unique morphological evolution originates from the Ostwald ripening effect and crystal growth inhibition caused by LSCM particles. Furthermore, LSCM particles with high oxygen vacancy concentration and a large work function significantly promote oxygen spillover and electron depletion on the surface of SnO₂ (6.80 eV for LSCM vs. 4.55 eV for SnO₂). As a result, LSCM-loaded SnO₂ FITs (LSCM@SnO₂ FITs) provide remarkably high response to formaldehyde (R_air/R_gas = 26.50 to 5 ppm) and excellent selectivity against interfering gases (H₂S, C₇H₈, NH₃, C₂H₆O, C₈H₁₀, CO, and C₅H₁₂) even without using noble metal catalysts. These observations demonstrate the potential use of LSCM@SnO₂ FITs for real-time monitoring of indoor air quality, especially toward formaldehyde, which has not been accurately detected by using conventional metal oxide based sensors.