MOF-based sensors for the detection of airborne α-pinene

Abstract

Two metal–organic frameworks, DUT-4(Al) and MIL-100(Fe), were explored as sensitive layers deposited at the surface of QCM transducers for the detection of α-pinene, a terpenic volatile organic compound encountered in indoor air at a trace level. Both sensors displayed sensitive, fast, reversible and repeatable response toward exposure to α-pinene, in complementary ranges of contaminant concentration: DUT-4(Al)@QCM was demonstrated to be attractive for the detection of α-pinene at 0.5 ppm < C_α-pinene < 4.8 ppm, while MIL-100(Fe)@QCM was found more efficient at C_α-pinene > 4.8 ppm. As an alternative to using two complementary QCM sensors, a single device prepared by coating the QCM by mixing DUT-4(Al) and MIL-100(Fe) was envisaged. Interestingly, DUT-4(Al)/MIL-100(Fe)@QCM benefited from a synergistic effect of both MOFs: it showed high sensitivity for detecting α-pinene in a wider range of concentration than that explored with sensors based on a single MOF, without losing the high level of sensor performances, in terms of response time, reversibility and repeatability.