ELECTROCHEMICAL RESEARCH IN CHEMICAL HYDROGEN STORAGE MATERIALS: SODIUM BOROHYDRIDE AND ORGANOTIN HYDRIDES

Open Access
Author:
McLafferty, Jason
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
December 17, 2008
Committee Members:
  • Digby D Macdonald, Dissertation Advisor
  • Digby D Macdonald, Committee Chair
  • Michael Anthony Hickner, Committee Member
  • Suzanne E Mohney, Committee Member
  • Michael John Janik, Committee Member
Keywords:
  • organic electrochemistry
  • electroreduction
  • hydrogen storage
  • sodium borohydride
Abstract:
Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from “spent fuel,” i.e., the material remaining after discharge of hydrogen. In this thesis, some research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the previous literature for electrochemical reduction of spent fuels, have been attempted. A quantitative analytical method for measuring the concentration of sodium borohydride in alkaline aqueous solution has been developed as part of this work and is described herein. Finally, findings from stability tests for sodium borohydride in aqueous solutions of several different compositions are reported. For aminoborane, other research institutes have developed regeneration schemes involving tributyltin hydride. In this thesis, electrochemical reduction experiments attempting to regenerate tributyltin hydride from tributyltin chloride (a representative by-product of the regeneration scheme) are described. These experiments were performed in the non-aqueous solvents acetonitrile and 1,2-dimethoxyethane. A non-aqueous reference electrode for electrolysis experiments in acetonitrile was developed and is described.