Research On Hydrogen Sensor Based On Proton Exchange Membrane Fuel Cell

Among many types of hydrogen sensors,proton exchange membrane fuel cell（PEMFC）hydrogen sensor has been widely studied for its high selectivity to hydrogen,operating at room temperature and low energy consumption.However,the traditional structure of PEMFC type hydrogen sensor needs to provide reference gas（air or oxygen）at the cathode side of membrane electrode assembly（MEA）,which leads to the complex structure of the sensor,high cost and the possibility of detonation of reference gas.In this dissertation,starting from the core component MEA of the sensor,a new type of PEMFC hydrogen sensor with low cost and simple structure without reference gas and its measuring device was designed and built.In addition,the influence of carbon carrier content in the MEA cathode catalytic layer on the sensing performance was investigated and the sensing mechanism of a new sensor was proposed.The main research results are as follows.（1）A new type of PEMFC hydrogen sensor with simple structure without reference gas was designed,and a miniaturized hydrogen sensor test device was built and optimized.The MEAs of 4 cm²catalytic layer was prepared by spraying commercial Pt/C as catalyst.The traditional hydrogen sensor assembled by PEMFC single pool fixture and the initial test device independently built were used to test the sensor performance of MEA.The maximum sensitivity of MEA is 0.339 m A%^-1,the response time range is 137-198 s,and the recovery time range is 95-205 s.By simplifying the flow field structure,using cheap copper plate instead of platinum-plated alloy bipolar plate,and removing the heating plate,a new hydrogen sensor with simple structure was designed and tested.The sensitivity of the sensor is 0.983 m A%^-1,the response time range is 21-108 s,and the recovery time range is 1-17 s.By reducing the volume of the test chamber in the sensor test device,a small test device was built.The sensitivity of the sensor is 0.546 m A%^-1,and its response time range is 10-67 s and recovery time range is 1-13 s.（2）The influence of the content of carbon carrier in the cathode catalytic layer on the new PEMFC hydrogen sensor with simple structure was investigated,and its sensing mechanism was studied.By adjusting the content of carbon carrier in the cathode catalytic layer,the sensing performance of MEAs with different content of carbon carrier was explored.It was found that the sensitivity of the sensor increased with the increase of carbon carrier content,and MEA 1（80%carbon carrier content）had the highest sensitivity of 0.546 m A%^-1.The response time and recovery time of MEAs with different contents of four carbon carriers were similar.The response time of MEA 1 is 16 s and recovery time is 1 s when hydrogen concentration is 0.5%,but the maximum response current,response time and recovery time all increase with hydrogen concentration.This is related to the role of carbon carrier in limiting hydrogen diffusion and providing larger specific surface area.