Self-assembly tourmaline@BiFeO₃ composites with enhanced polarization for dual-selective C₃H₆O and H₂S detection

Ferroelectric oxides with great polarization have attracted much attention due to the polarization modulated carrier behaviors causing high gas sensitivity in detecting hazardous toxic gases. In this work, tourmaline@BiFeO3 (T@BFO) composites were fabricated by the sol-gel method based on the electrostatic self-assembly strategy for the C3H6O and H2S detection. It is found that BFO nanoparticles are uniformly distributed on tourmaline due to the strong electrostatic field of tourmaline. In comparison with pure BFO, the T@BFO composites showed an improved gas sensitivity. More importantly, the sensor based on 3.0-T@BFO can effectively detect C3H6O at 150 degrees C and H2S at 210 degrees C in limits of detection as low as 50 and 7 ppb, respectively. The results exhibit that 3.0-T@BFO composites have lower activation energies (E-act) of C3H6O at 150 degrees C and H2S at 210 degrees C, which endow 3.0-T@BFO with dual-selectivity for C3H6O and H2S. The Ex-situ XPS and density functional theory calculations further reveal that tourmaline activates the sensing site of BFO to achieve selective adsorption of C3H6O at Bi, Fe, and oxygen vacancies sites and H2S at surface lattice oxygens, Fe and oxygen vacancies sites. These results provide an efficient strategy to design practice multifunctional and highly sensitive gas sensors for detecting hazardous toxic gases.