Plasmon-damping Chemical Sensor for Hydrogen Fuel Monitoring

Abstract

Hydrogen (H 2 ) is a clean, sustainable, and highly energy efficient fuel source which will meet the increasing energy demand. Fuel cells can utilize H 2 and convert it into electric energy with high efficiency. However, the usage of fuel cells is limited by degradation of their performance by even trace levels of sulfur impurities (<100 ppb) present in H 2 . Therefore, there is a vital need for trace level sulfur sensors to monitor the quality of H 2 fuel utilized in fuel cells. The present thesis demonstrates a novel chemical sensor using an indigenous sensing scheme: adsorbate-induced damping of hybrid plasmon resonance, associated with Ag nanoparticles, to detect ppb levels of sulfur impurities in H 2 . The nanoparticles report the full width at half maximum (FWHM) or plasmon-damping factor through optical extinction. Subsequently, H 2 S concentration is calculated using time rate of change of plasmon-damping factor in the initial linear regime. Results have shown that the change in plasmon-damping factor related to sulfur adsorbates follows multiple Langmuir adsorption isotherms. Further, the time rate of change of plasmon-damping factor (i.e., slope) corresponding to first Langmuir isotherm in linear regime has shown a linear response to H 2 S concentration. It is also revealed that the sensitivity and response time of the present sensor is strongly dependent on H 2 S:H 2 gas flow rate. The sensor has shown a low detection limit of 65 ppb H 2 S:H 2 , for which a response time of 10 s is observed, using a gas flow rate of 520 sccm.