Synthesis and electrochemical study of Ptlr and PtRu nanomaterials
Alammari, Walaa S.
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The rapidly growing need for clean energy on a global scale has led to the emergence of new fields of scientific research to facilitate the discovery and development of novel energy sources, such as fuel cells, which generate significantly lower environmentally harmful contaminants, in contrast to traditional fossil fuels. The direct methanol fuel cell (DMFC) is a promising future energy technology alternative due to its high energy conversion efficiency, minimal level of pollutant emissions, the attractive energy density of methanol fuel, and its ease of availability. To date. Platinum (Pt) has been the most effective catalyst in DMFCs, and has been utilized as anodic and cathodic catalysts in many other applications. In this M.Sc. thesis, Platinum-Iridium (Ptlr)-and Platinum-Ruthenium (PtRu)-based nanomaterials have been synthesized and investigated to demonstrate their application in DMFCs, as anodic and cathodic catalysts. Analyses of the surfaces of synthesized Pt, and Ptir-and PtRu-based nanomaterials were performed by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the synthesized nanomaterials were elucidated via cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). A nanostructured Ti02NT substrate was used for these investigations. The synthesis of Titanium dioxide nanotube materials (Ti02NT) was accomplished through the anodization of Ti02NTs possess a highly active surface area following their treatment with UV light. Pt and Ir were subsequently deposited onto the Ti02NTs, and the resulting Ti02NT/PtIr electrodes were fabricated by chemical reduction method. Several Ti02NT/PtIr and Ti02NT/PtRu electrodes with different compositions were studied and compared with the Pt modified Ti02NT electrodes. The fabricated Pt and Ptir, and PtRu catalysts were characterized by SEM, EDX, whereas the electrocatalytic activity toward methanol oxidation was investigated by CV, CA, and EIS. The results indicated that the PtIr/Ti02NT with a Pt:Ir ratio of 60:40 andPtRu/Ti02NT with a Pt:Ru composition of 60:40 composites possessed the highest methanol oxidation activity and stability. In addition, a series of reduced graphene oxide (rGO) and PtRu nanoparticle nanocomposites with different atomic ratios of Pt:Ru (100:0, 84:16, 69:31, 64:36, 42:58 and 0:100) were deposited onto the Ti02NTs (as Ti02NT/rGO-PtRu) and tested for their impacts on the oxygen reduction reaction (ORR) in the DMFCs. Ti02NT/rGO-PtRu nanocomposites were fabricated using a electrochemical deposition technique, and then characterized by SEM, EDX, and XRD. The electrocatalytic activity was subsequently investigated by CV, CA, and EIS. The Pt:Ru with a ratio of 64:36 exhibited the highest stability and electrocatalytic activity toward ORR, which is promising for environmental and green energy applications.