Study On The Hydrogen Sensing Properties Of Pt-Pd/Reduced Graphene Oxide

As a potential new energy,hydrogen has been widely used in all walks of life. However, hydrogen is flammable and explosive in air over a concentration of 4vol% and can hardly be perceived since it is odorless and colorless. Therefore hydrogen leakage detection and alarm have become essential. Graphene shows good prospect in novel sensor application because of its unique properties of high surface area and high carrier mobility. Platinum(Pt) and palladium(Pd) metals have high solubility and selectivity to hydrogen, hence the performance of Pt and Pd nanoparticales decorated graphene hydrogen sensor has great potential to be improved.In this paper, graphene oxide was obtained by a modified Hummer’s method and ultrasonic stripping process. Pt-Pd nanoparticles decorated reduced graphene oxide(Pt-Pd/RGO) had been synthesized via a simple one-step chemical reduction. Pt-Pd nanocrystals were uniformly dispersed on RGO surface. Micro electrodes, which can be used for the miniaturization and integration of hydrogen sensor, were obtained using the technology of the lithography process. The Pt-Pd/RGO based sensor was assembled on electrodes by using dielectrophoresis process. Hydrogen sensing properties measurement system was set up, which could provides different experiment conditions and test hydrogen sensing properties in real time.We carried out a series of tests, including the I-V, sensitivity, repeatability and stability of the Pt-Pd/RGO based sensor. The hydrogen sensor was tested under different conditions such as temperature, humidity, flow rate and gas carrier, in order to investigate the influence of these environmental factors on the sensing properties of the sensor. The following are conclusions:1. By comparing the I-V curves of RGO and Pt-Pd/RGO based sensor at different hydrogen concentrations, it showed that the Pt-Pd nanoparticles had obvious selective effect to hydrogen.2. The sensing properties of the sensor were tested under the condition of increasing hydrogen concentrations. Results show that the sensor had good performance and the current response signal increased with the increase of concentration.3. The sensor showed good stability and repeatability with the cyclic hydrogen adsorption and desorption.4. The sensor showed a high sensitivity to hydrogen, the lowest detection concentration of hydrogen can reach 50 ppm at room temperature, the response time decreased and the recover time was prolonged with the increase of hydrogen concentration.5. The experimental results of the influence of different environmental factors on the performance of the sensor show that the performance of the sensor is greatly affected by temperature, humidity and gas carrier, and the influence of the gas flow rate in a certain range can be neglected.6. Hydrogen sensing response of the Pt-Pd/RGO based sensor is closely related to the Pd lattice expansion, the formation of Pd/H and Pt/H and the change of surface carrier concentration of graphene.