Facile synthesis of mesoporous CdS/PbS/SnO2 composites for high-selectivity H2 gas sensor

In this work, novel mesoporous heterostructures composed of CdS, PbS and SnO2 (CdS/PbS/SnO2) were synthesized via a green and facile treatment. Interestingly, when the CdS/PbS/SnO2 composites were assembled into sensing layer for the fabrication of H2 gas sensor for the first time, the sensor based on CdS/PbS/SnO2 exhibited more prominent gas-sensing properties than those of the CdS/SnO2 and PbS/SnO2 sensors. The CdS/PbS/SnO2 sensor showed a fast response/recovery time of 10.6/36.9 s towards 100 ppm H2 gas at 200℃, with an ultralow limit of detection of 50 ppb (17.3 %), and the sensor had a largely enhanced response of 1125.2 %, which was approximately 16.8 and 7.4 times higher than those of the CdS/SnO2 (66.8 %) and PbS/SnO2 (151.4 %) sensors. In addition, the CdS/PbS/SnO2 sensor had an outstanding selectivity towards H2 gas against other gases, reliable reversibility and long-term stability for 40 days. Such enhanced properties was mainly attributed to the large surface-to-volume ratio, which can provide abundant active sites to gas adsorbtion and diffusion in surface redox reaction. Moreover, more numerous heterojunctions of the CdS/PbS/SnO2 composites may serve as highly conductive channels to accelerate carrier transfer, thus further leading to an improved performance of the sensors. Credibly, our present work will foresee a great potential application for ppb-level H2 gas monitoring in an extreme environment.