Study On The Hydrogen Sensing Properties Of Pd/SnO₂/RGO Nanocomposites

Hydrogen gas is an attractive new energy source because of its clean and high energy conversion efficiency.But it will lead to explosion when the concentration of hydrogen in the air is more than 4%.Hence,we must use sensors for real-time monitoring of hydrogen during the producing and operating progress.The sensing materials decide the sensor performance,so the improvement of sensor performance depends on the selection of sensing materials.Due to its unique features of high surface area,high electron mobility and mechanical strength,graphene has broad application in hydrogen sensors.In this paper,the Pd/RGO and Pd/Sn O₂/RGO nanocomposites as sensing materials have been synthesized by one-step and two-step reduction,respectively.The gas-sensitive elements were fabricated on interdigital electrode by dielectrophoresis?DEP?technology.The hydrogen sensing properties of Pd/RGO and Pd/Sn O₂/RGO nanocomposites was comparatively investigated with respect to different concentrations,operating temperatures,repeatability and gas species in a specially dynamic test system.In the end,the sensing mechanism for the detection of H2 is also discussed.The following conclusions are obtained:1.GO powder was prepared from natural graphite powder by a modified Hummer's method form a stable.RGO was obtained by ultrasonic stripping and chemical reduction method.The test results show that no obvious response was observed after introduction of H2 gas into pure RGO.The Pd/RGO nanocomposites as sensing materials have been synthesized by one-step reduction method.The gas-sensitive element based on Pd/RGO nanocomposites for hydrogen has certain response,but the response sensitivity is not high and a longer response and recovery time.2.The Pd/Sn O₂/RGO nanocomposites as sensing materials have been synthesized by two-step reduction method.The gas-sensitive element based on Pd/Sn O₂/RGO nanocomposites showed higher sensitivity and a better response and recovery time compared with sensor based on Pd/RGO nanocomposites.3.The response of the gas-sensitive element toward various gases at 3000 ppm,which include NH3,C2H2,NO₂,C2H6 O,and H2.At the same conditions,the response of the gas-sensitive element toward H2 is the largest,indicating that the H2 gas-sensitive element based on Pd/Sn O₂/RGO nanocomposites exhibits excellent selectivity compared with other interferential gases.