Highly Sensitive QCM Humidity Sensor Based on Fullerenol-Assisted Dispersion of Nafion/MWCNTs Composites

Water seepage of building walls is a common problem in our lives. However, the lack of early seepage detection methods often makes the problem worse. To develop effective early wall seepage detection methods, an ultrasensitive quartz crystal microbalance (QCM) humidity sensor based on fullerenol (C60-OH)-assisted dispersion of Nafion/multiwalled carbon nanotubes (MWCNTs) composites is proposed. The prepared sensor shows almost seven times higher frequency shift than pure Nafion-based sensor, which reaches −10814 Hz. This is mainly attributed to the uniform dispersion of MWCNTs in the Nafion with the assistance of C60-OH to form a reticular structure that generates more voids, which greatly improves the diffusion ability of water molecules in the composite materials and thus further enhances humidity sensing properties of the sensor. The high-performance QCM humidity sensor is expected to be used for early detection of water seepage in building walls by monitoring air humidity changes near the wall surface.