Role of vanadium oxide and palladium multiple loading on the sensitivity and recovery kinetics of tin dioxide based gas sensors

The simultaneous improvement of sensor response and response/recovery kinetics is important for repeated gas monitoring using high-performance semiconductor gas sensors. In this study, we attempted to add two different types of catalysts to the SnO2 nanoparticles to enhance their responsive properties and investigated the impact of each catalyst on co-loaded SnO2 nanoparticles. V2O5 and Pd were loaded on sphere-type SnO2 nanoparticles by a simple impregnation method, and we evaluated the effect on the sensor response to H2 and recovery speed. Separately, V2O5 and Pd loading effectively enhance the sensor response and rapid recovery reaction, respectively, because V2O5 provides SnO2 with reactive adsorbed oxygen, and Pd enhances the catalytic activity on the particle surface. Further, V2O5- and Pd-co-loaded SnO2 shows both high sensor response and rapid recovery reaction. Thus, co-loaded SnO2 is improved by V2O5 and Pd simultaneously, and the two loadings are complementary. In particular, V2O5 loading reduces the recovery speed due to the re-oxidization of V2O5 on SnO2. However, Pd accelerates V2O5 re-oxidization by catalytic activity and the recovery kinetics of the co-loaded SnO2. Therefore, this fundamental investigation offers a suitable material design for additives, which can be applied to manufacture high-performance electrochemical devices such as semiconductor gas sensors.