Pd nanoparticles decorated SnO2 ultrathin nanosheets for highly sensitive H2 sensor: Experimental and theoretical studies

This study is attempted to improve the hydrogen sensing performance of SnO 2 based sensors by simultaneously employing two strategies of morphology control and noble metal loading. Therefore, SnO 2 ultrathin nanosheets with thickness not exceeding 3.5 nm were successfully synthesized by a hydrothermal method and then different content of Pd nanoparticles were uniformly loaded onto SnO 2 surface by in situ reduction with ascorbic acid . The gas sensing properties demonstrated that the introduction of Pd not only altered the selectivity of the SnO 2 sensor from ethanol to hydrogen, but also significantly improved the gas sensitivity and reduced the working temperature. And the optimal 1.0%Pd/SnO 2 sensor owned the highest sensitivity (75), fastest response-recovery property (21 s/13 s) to 20 ppm of hydrogen at 220 °C, and the actual detection limit is as low as 0.1 ppm. Furthermore, 1.0%Pd/SnO 2 sensor exhibited excellent repeatability, reproducibility and acceptable anti-interference of humidity. The DFT studies suggest that the physisorption of the hydrogen molecules on the surface of SnO 2 , but chemisorption on the surface of Pd/SnO 2 . The improved H 2 sensing performance of Pd/SnO 2 sensor attributes its ultrathin thickness of SnO 2 and catalytic dissociation of Pd to O 2 and H 2 .