Design And Performance Of Amperometric Hydrogen Sensor Using Graphene-based Platinum Nanocomposites

With the rapid development of global economy and urbanization, the increasing demand for energy and the depletion of fossil resources lead to the difficulty in meeting the needs of human development. Hence, the exploitation and utilization of clean energy has become a top priority. As a kind of ideal clean energy, hydrogen has been widely applied to many fields. It can be used as a high-energy fuel to weld or cut metal, as a reductant to refine precious metal in metallurgical industry, and as an important raw materials in chemical industry. However, hydrogen is a colorless and odourless gas which can not be perceived by human sensory organs, and it is inflammable and explosive with a wide range of explosion and a low level of lower explosive limit when meeting fire in the air. For security, hydrogen leak must be strictly monitored. Therefore, in order to ensure that hydrogen can be safely used in these areas, it is very significant to prepare hydrogen sensors with rapid response,good stability and high sensitivity. Electrochemical hydrogen sensors has been widely applied in hydrogen detection because of their inherent advantages, such as good safety and reliability, Measurement accuracy, fast response low power consumption and so on. In this paper, a novel fabrication procedure of amperometric gas sensors is obtained by investigating the preparation and assembling of sensor electrodes. In addition, the graphene-platinum nanocomposite is prepared by a wet chemical route,to carry out a series of experiments as an amperometric hydrogen sensor. The paper is divided into two parts:Firstly, as a conventional catalyst, the platinum-ruthenium nanomaterial is used to investigate the fabrication process of amperometric gaseous diffusion electrode,followed by assembling and testing of the sensor. According to the reported methods in literature, we improved the experimental process and parameters to obtain a porous diffusion electrode, whose surface is covered with uniform and continuous catalyst with high mechanical strength and other properties. At the same time, the assembly method uses silica to separate the three electrode separators to improve the stability of the sensor. Through the novel production process, the sensor is endowed with high sensitivity, good stability and fast response time and other advantages. After testing and optimization, the sensor with excellent performance is combined with a external circuit board to construct a hand-held portable gas detection alarm. This method willbe helpful to the future production of electrochemical gas sensors.Secondly, graphene is prepared by a mild wet chemical route, and platinum nanoparticles is then decorated on graphene by a one-step reduction method,obtaining the graphene-Pt nanocomposite to construct a novel amperometric hydrogen sensor. The as-prepared sensor electrode has a low Pt load(only 0.8 mg/cm2) which considerably decrease the consumption of noble metal compared with commercial sensors, while exhibiting a high sensitivity of 162 nA/ppm, a low detection limit of1.5 ppm, and a response time of 20 s. Besides, the sensor has good linearity,repeatability and selectivity. The excellent performance is mainly attributed to the inherent gas-sensitivity and high conductivity of graphene, which provides large surface area and abundant binding sites for the electrochemical reaction between Pt and hydrogen. In addition, this method can also be used to prepare other electrochemical gas sensors by compositing other noble metal or transition metal catalysts with graphene.