Detection of hydrogen sulfide: the role of fatty acid salt Langmuir–Blodgett films

Different fatty acid salt (cadmium arachidate, lead arachidate, zinc arachidate etc.) Langmuir–Blodgett (LB) films were deposited onto piezoelectric quartz crystal microbalance (QCM) electrode surfaces. The reaction kinetics of the LB films with hydrogen sulfide (H2S) molecules was monitored using nanogravimetric technique. The exposure of H2S gas into the LB films showed a fast response that was manifested by a dramatic change in the frequency of QCM at the initial stage. The influences of film deposition method, film thickness, type of metal ion, concentration and pressure of H2S gas upon gas sensing properties were investigated. The fast and irreversible reaction of LB films with H2S gas suggests that fatty acid salt LB films can be a potential candidate for gas sensing applications.