Modified fermi level in strontium nanoparticles decorated reduced graphene oxide for wide concentration detection of nitrogen dioxide at room temperature

We demonstrate room temperature nitrogen dioxide (NO₂) sensing at parts per billion level (ppb) using a chemiresistive sensor based on strontium nanoparticles decorated reduced graphene oxide. Among the various functional materials used for NO₂ sensing, it is a unique study reported for the first time using hybrid of reduced graphene oxide with a low work function alkaline earth metal. An increase of nearly 222% in sensing response is observed in the hybrid device over reduced graphene oxide alone at a concentration of 1 ppm. Moreover, the hybrid device exhibits a good sensitivity to NO₂ over a wide concentration range from 500 ppb to 104 ppm. Additionally, the hybrid device is highly selective to NO₂ amongst other pollutants. The integration of strontium nanoparticles onto reduced graphene oxide imparts excellent performance to the hybrid sensor due to their high adsorption energy for NO₂. Further, strontium nanoparticle, being a low work function material, raises the fermi level of reduced graphene oxide and populate it with more electrons thus facilitating rapid charge transfer to electrophilic nitrogen dioxide. Hence, strontium nanoparticles attribute to an important role in fast and selective adsorption of nitrogen dioxide at room temperature with underlying graphene helping in rapid charge transfer.