The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

In this paper, we investigate humidity sensing through impedance measurements with TiO2 nanoparticles (about 6 nm in diameter). The transient behavior and the impedance spectra are measured and interpreted from the theoretical point of view. Large responses are shown especially in the relative humidity range from 30% to 80%, which are essentially explained by condensation in the nanopores. The effect of the addition of Au nanoparticles is investigated and as expected, the Au/TiO2 interfaces allow for dramatically reducing the sensing film response time and above all, its recovery time; moreover, it seems to favor condensation when the relative humidity overcomes 70%.