This Is AuburnElectronic Theses and Dissertations

Platinum nanoparticle-polyoxometalate based bimetallic catalyst for proton exchange membrane fuel cell and bipolar electrodeposition based combinatorial material library applied in sensors and energy systems




Ramaswamy, Rajakumari

Type of Degree



Chemistry and Biochemistry


The first part of chapter 1 summarizes the reports on the improved oxygen reduction reaction (ORR) kinetics on Pt-bimetallic catalysts used in proton exchange membrane fuel cell (PEMFC). An account on the significance of polyoxometalate (POM), an inorganic ligand system to stabilize the base metal component of a multimetallic ORR catalyst, is given in addressing the issue associated with the instability of bimetallic Pt alloy surface under PEMFC cathode operating condition. The second part of chapter 1 deals with the significance of combinatorial material library and various methods including bipolar electrochemistry to synthesize the material library. Chapter 2 deals with a bimetallic ORR catalyst system composed of Pt nanoparticle (PtNP) and Co-substituted Dawson type polyoxometalate (Co-POM). The fabricated electrocatalysts films (POM-stabilized PtNP, cysteamine- or poly (diallyl dimethyl ammonium chloride) (PDDA)-stabilized PtNP/POM layer-by-layer (LBL) assembly) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The ORR kinetics of the electrocatalysts were studied using the rotating disc electrode (RDE) experiment. We confirmed our hypothesis that Co center in Co-POM helps promote O=O bond splitting and transfer the split O atom to the PtNP surface from the ORR kinetics using the PDDA-stabilized PtNP/POM LBL assembly. In chapter 3, we report the synthesis of Ag-Au alloy gradients on stainless steel substrates using bipolar electrodeposition (BP-ED). The alloy gradient was characterized using SEM/EDX. Confocal Raman microscopy was employed to determine the optimum alloy composition of 70 atomic% Ag/30 atomic% Au that resulted in the maximum surface enhanced Raman scattering (SERS) intensity and the optimum composition is explained on the basis of composition-dependent changes in the local surface plasmon resonance (LSPR) of the electrodeposited Ag-Au alloy. Chapter 4 deals with the Pd-Au alloy gradient generated by bipolar electrodeposition on a gold bipolar electrode, its characterization using SEM/EDX and its screening for the electrocatalytic activity towards formate oxidation using Raman spectroelectrochemistry. The optimum composition, 70 atomic% Pd/ 30 atomic% Au, is explained based on the band theory model applied to alloys between metals from group VIII and IB. Chapter 5 summarizes my research work and provides the directions for future studies.