The Electrocatalytic Behavior of Bismuth-Modified Platinum: Platinum-Bismuth Alloy versus Bismuth Adatoms

In this dissertation, new electroanalytic measurements and electron microscopy observations are applied to obtain fundamental understanding of how the incorporation of bismuth (Bi) with platinum (Pt) either as an alloy or a surface adatom Pt enhances the dimethyl ether electrooxidation reaction (DMEOR). Previous works have shown that incorporating other metals into a Pt electrocatalyst, such as Ru, Cu, or Bi, enhances electrooxidation activity toward DME, formic acid, ethanol and other organic compounds. When incorporated in alloy form and then dealloyed, these metals can potentially benefit structure sensitive electro-oxidation reactions through both the electronic effect of alloying as well as by increasing the strain in the Pt lattice structure when dealloyed, altering the bond length. When surface adatoms or complexes are used, they can also prevent poisoning of the catalytic surface by promoting the oxidation of intermediate species such as COads through either bi-functional or ensemble effects. The role of atomic surface structure in Bi-modified catalysts on DMEOR activity has not been previously revealed. In addition, while previous research has demonstrated the improved durability of Bi-containing electrocatalyst during DMEOR, an explanation as regards how poison resistance correlated to surface reactivity was not provided.