Synthesis and study of palladium-containing nanomaterials for hydrogen technologies

Abstract

We are currently facing a climate change and global warming effect due to the emission of greenhouse gases from our existing energy sources. A hydrogen-based economy is one solution to uphold our standard of living while lowering our carbon emissions. Palladium has the potential to play a major role in many aspects of the hydrogen-based economy, from purifying hydrogen to harnessing the energy via fuel cells and storing hydrogen as PdH x . In my M.Sc. study, Pd-based nanomaterials have been synthesized and examined for their applications in various hydrogen technologies. Surface properties of the synthesized Pd-based nanomaterials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N 2 gas adsorption/desorption. Electrochemical analysis of the fabricated materials was performed using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA). Other characterization methods were also applied such as inductively-coupled plasma atomic emission spectroscopy (ICP-AES), density functional theory (OFT) calculations, and hydrogen gas adsorption/absorption. The adsorption of the catalytically poisoning species, carbon monoxide, was also examined on Pd, PdPt, and PdAu nanostructures. The relative quantities of CO molecules adsorbed to surface of the catalysts decrease in the order of: PdPt > Pd > PdAu. It was found that the possible adsorption sites of CO can be tuned by alloying Pd with metals to which CO has different binding strengths. The work done in this thesis shows that by alloying Pd with other metals, both geometric and electronic properties are changed drastically. This has a major influence on the applications of Pd for hydrogen technologies.