Polypyrrole Nanoparticles Suspended on Graphene for the Detection of Simulant Chemical Warfare Agents

This letter develops a gas sensor based on graphene decorated with polypyrrole (PPy) nanoparticles (NPs) for the detection of dimethyl methylphosphonate (DMMP), a chemical warfare agent simulant. The PPy nanoparticles were synthesized via chemical polymerization with an average diameter of 110 nm and randomly distributed onto exfoliated graphene. The nanomaterials were characterized using field emission scanning electron microscopy, confirming the successful decoration of PPy nanoparticles on the graphene surface. The gas sensing performance of the sensor was evaluated at ambient temperature, demonstrating high stability and reversible interaction with DMMP. The sensor exhibited a linear response to several concentrations of DMMP, with a sensitivity of 14.2% per ppm. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 171 and 572 ppb, respectively, revealing the sensor's capability to detect trace levels of DMMP. The excellent sensing performance can be attributed to the synergistic effect between both p-type nanomaterials, graphene, and PPy. Graphene facilitating fast and efficient charge transfer as transduction element while PPy NPs providing noteworthy reactivity with DMMP by means of hydrogen bonding. Overall, the graphene-PPy nanocomposite sensor shows great potential for the sensitive trace level detection of DMMP in real-world applications.