Synthesis of Nanoparticles and Organometallic Complexes for Gas Sensing

Abstract: Currently metal nanoparticles (NPs) are a subject of interest regarding many applications, in particular chemical gas sensing, as the associated environmental issues are of substantial importance. Metal NPs are attractive due to their fascinating optical properties and primarily, localized surface plasmon resonance (LSPR) which strongly depends on size and shape of NPs. Desired size and shape of NPs can be achieved by colloidal synthesis that allows for flexibility in the reaction conditions, although it demands high precision and understanding of how different factors affect NP formation, which can influence the quality of synthesized NPs. Regarding chemical sensing, phthalocyanines possess strong activity towards some gases, and they carry interesting optical properties, therefore their application is also interesting. This thesis focuses extensively on the synthesis and characterization of Pd NPs for hydrogen sensing. The Pd NPs synthesis was optimized with regard to the concentration needed for efficient response from the sensor. The Pd NPs were incorporated into a polymer matrix to be protected from poisoning, which also led the diffusion path between hydrogen and Pd NPs to be extended. Different stabilizing agents for Pd NPs were examined in order to explore how common stabilizing compounds and their interactions with Pd NPs may influence the sensing process. The work was focused on the use of homogeneous surfactant and polymer coatings on Pd nanofabricated surfaces, which were examined and analyzed in hydrogen sensing. Additionally, to address hydrogen sensing problems i.e. hysteresis, PdAu alloys with various Pd:Au ratios were colloidally synthesized and thoroughly characterized. PdAu alloys exhibited excellent results of hysteresis removal at specific Pd:Au ratios. Moreover, phthalocyanine based complexes; Zn, Co, Cu, Fe, were synthesized for application in NOx monitoring.