Surface photocurrent gas sensor with properties dependent on Ru(dcbpy)2(NCS)2-sensitized ZnO nanoparticles

An original photoelectric gas sensor, fabricated by Ru(dcbpy)2(NCS)2 (dcbpy = 2,2′-bipyridyl-4,4′-dicarboxylate)(RuN3)-sensitized ZnO on a comb-like electrode by surface photocurrent technique with excitation of visible light (545 nm), is presented for CO and O2 detection at room temperature. The surface photocurrent (ISPC) of a sample can be dramatically enhanced and diminished depending on the properties of the gases. As a reductive gas, CO can make ISPC increase and the sensor response is linear to the change in CO concentration with a detection limit of 0.62 Torr. However, ISPC decreases upon O2 adsorption, since it can capture electrons from the surface. There is no linear dependency between ISPC and concentration of O2. In this article a microscopic mechanism of the photoelectric gas sensor has also been discussed in detail. This research should be valuable for the practical application of the ZnO gas sensor.