Polyoxometalate as electron acceptor in dye/TiO2 films to accelerate room-temperature NO2 gas sensing

It is an effective strategy for increasing the sensitivity and shortening the response/recovery time of semiconductor gas sensors used at room temperature with visible light illumination. However, the large band gap and the serious carrier recombination under light illumination of the semiconductor will hinder the improvement of room temperature sensing performance. Herein, we assembled the films of TiO2 nanoparticles decorated with polyoxometalate (POM) and organic dye molecules to enable accelerated room-temperature NO2 gas sensing (25 ℃) under visible light illumination. The POM molecule as electron acceptor in the dye/TiO2 films can enable the rapid separation and transport of photogenerated carriers. Combining with organic dyes, POM decorated dye/TiO2 films exhibited excellent sensing characteristics over a wide range of NO2 concentrations (50ppb-5 ppm), such as high sensitivity (233.1–1 ppm), relatively low detection concentration, and high selectivity. Moreover, the response/recovery time of NO2 from the surface of this sensitive films could be constantly controlled down to 48 s and 66 s, respectively, without any thermal energy.