Mechanistic Studies in Water Splitting Systems

Open Access
Author:
Kaintz, Anne Elizabeth
Graduate Program:
Chemistry
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Mallouk/Maroncelli, Thesis Advisor
  • Thomas E Mallouk, Thesis Advisor
Keywords:
  • hydrogen reduction catalysts
  • RDE
  • niobium electrodes
  • fabrication
  • homemade
  • UME
  • ultramicroelectrodes
  • photodeposition
  • degradation
  • hexaniobate nanoscrolls
Abstract:
In the first of two projects, electrochemical kinetics studies were intended to elucidate the mechanism of hydrogen reduction at a Rh/Cr2O3 (core/shell) reduction catalyst for future development in a water splitting system. Ultramicroelectrode (UME) fabrication, including photodeposition and electrodeposition of Rh and Au, and the reliability of the resulting electrodes were explored. It was determined that rhodium does not bind strongly enough to glassy carbon by these photodeposition techniques to allow for its use on rotating disk electrodes. Epoxy deteriorates under conditions of rhodium photodeposition. Niobium is unfit for exposed electrode surfaces because of its many different oxide states. Gold UME surfaces recede with use into their glass insulation surroundings. And 25 μm thick gold and rhodium wires disintegrate in flames too quickly to allow for their use in traditional UME construction. In the second project, flash-photolysis and time-resolved photolysis studies were intended to illuminate the kinetics of charge transfer for the reduction half of a water splitting system involving hexaniobate nanoscrolls, nanoparticulate Pt reduction catalysts, and Ru(bpy)2(4,4’-(PO3H2)2bpy)2+ dye. Solid state synthesis and exfoliation techniques were used to produce the nanoscrolls, and XRD and TEM were used to confirm the identity of the product and success of Pt photodeposition.