Raman and XPS studies of ammonia sensitive polypyrrole nanorods and nanoparticles

Abstract

Raman and XPS studies of ammonia sensitive polypyrrole nanorods and nanoparticles, respectively and tested upon ammonia exposure using Raman and X-ray photonelectrone spectroscopy (XPS). Characterization of both nanomaterilas via Raman spectroscopy demostrates the formation of PPy, displaying vibration bands consistent with the literature. Additionally, XPS reveals the presence of neutral PPy species as major components in PPy NRs and PPy NPs, and other species including polarons and bipolarons. Raman and XPS analysis after ammonia exposure show changes in physical/chemical properties of PPy, confirimg the potential of both samples for ammonia sensing. Results demostrate that electrochemically synthesized NRs involve both proton and electron transfer mechansims during ammonia exposure, as oposit to the chemically synthesized NPs, which show the mechamism dominated by electron transfer. Thus, the different detection mechanisms in PPy NRs and PPy NPs appear to be connected to the particular morphological and chemical composition of each film. These results contribute to elucidate the mechanisms involved in ammonia detection and influence of the synthesis routes and physical/chemical characteristics of PPy.