Mesoporous polydopamine microspheres for rapid ppb-level ultra-sensitive formaldehyde detection.

Mesoporous polydopamine (PDA) microspheres were synthesized and employed as the sensing layer of a quartz crystal microbalance (QCM) sensor for ultra-sensitive formaldehyde (HCHO) detection. Structural characterizations confirm uniform spherical morphology, abundant mesopores (~ 20 nm), and a high specific surface area of 62.28 m2/g, providing rich adsorption sites. Benefiting from the porous architecture and abundant functional groups, the optimized sensor exhibits a minimum test concentration of 5 ppb, a high sensitivity of 2.451 Hz/ppb, and an excellent linear response (R2 = 0.9966) in the 5-40 ppb range. Rapid response and recovery times of 3 s and 4 s are achieved at room temperature. Moreover, the sensor demonstrates good repeatability, long-term stability, and high selectivity toward HCHO, with humidity shown to further enhance the sensing response. These results highlight the strong potential of mesoporous PDA microspheres for high-performance HCHO sensing.