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

Abstract

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.