A sub-second response/recovery hydrogen sensor based on multifunctional palladium oxide modified heterojunctions

Abstract

H2 possesses a wide range of applications. Due to the low ignition energy of H2 and the low explosion limit in air, it is necessary to establish rapid detecting systems. However, the sub-second response/recovery is still a serious issue for H2 sensors. In this work, a sub-second response/recovery H2 sensor based on multifunctional PdO modified SnO2/ZnO heterojunctions is successfully fabricated. The Pd-SnO2/ZnO sensors exhibit the response/recovery time of 0.8/0.8 s to 50 ppm H2, which are faster than the existing H2 sensors of analogous structures. The strong metal–support interaction between PdO and SnO2/ZnO enhances the presence of oxygen vacancy (VO), vacancy oxygen (Ov) and adsorbed oxygen (Oc) in the sensitive materials, which are crucial components for achieving rapid response/recovery times. Another function of PdO is that H2 is oxidized more easily when it was fixed on SnO2/ZnO. Multilevel heterojunction enriches the surface electrons of Pd-SnO2/ZnO, which is conducive to adsorb more oxygen molecules and target gas. Due to the multifunctional function of PdO and the modification of multilevel heterojunction, the response/recovery time of H2 sensors are shortened to sub-second. This study may provide a new approach for the design of fast response gas sensor, and Pd-SnO2/ZnO sensors have been shown to be potential candidates for real-time hydrogen monitoring.