Chemiresistive hydrogen sensors using Pd/Ag alloy monolayer-protective clusters

IBAÑEZ, FRANCISCO J.; ZAMBORINI, FRANCIS. P.; PARRINO, JOSEPH

University of Ohio

Conferencia; 39th Central Regional Meeting of the American Chemical Society (ACS); 2008

Ohio University

Chemiresistive Hydrogen Sensing with Films of Pd and PdAg Alloy Nanoparticles Francis P. Zamborini, Francisco J. Ibanez and Joseph E. Parrino, University of Louisville, Louisville, KY Here we describe the use of Pd and PdAg alloy nanoparticles for chemiresistive H2 sensing down to 0.10 % in a H2/N2 mixture. The procedure involves synthesis of organic-soluble Pd and PdAg alloy nanoparticles coated with alkanethiolates, alkylamines, or surfactants followed by simple drop-cast deposition across two electrodes separated by a microscale gap. The resistance of the films changes in the presence of H2. The sensing behavior greatly depends on the type of nanoparticle coating and alloy composition. For example, Pd nanoparticles coated with strong binding thiol ligands respond to H2 only after treating the film with ozone or heat, where as alkylamine- and surfactant-coated Pd nanoparticles respond immediately following drop-cast deposition. For alkylamine-coated Pd nanoparticle films, the sensing behavior also depends on the alkyl chainlength. The PdAg alloy nanoparticles exhibit improved sensing behavior and reduced cost. In this talk, we will describe the sensing behavior of these films as a function of the protecting ligand and alloy composition. We characterized the films by atomic force microscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy experiments to correlate morphology and composition with the observed sensing response, leading to a better understanding of the sensing mechanism. The reported films have great potential for H2 sensing applications, such as in leak detection or in fuel cell technology, due to their easy, low cost preparation, low power consumption, fast response, and high sensitivity.