Defence Jennifer Hong: "Synthesis and Electrocatalytic Application of Novel Metal Borides Nanomaterials"

Promotors: Prof. Paolo P. Pescarmona and Prof. Loredana Protesescu

Abstract:

In this PhD research work, we developed the synthesis and investigated the electrocatalytic properties of nickel boride (NixBy) nanocrystals. Our method to synthesize NixB nanopowders is through novel solid-state method. For the solid-state synthesis, we employed the use of commercially available Ni and B salts and studied the reaction between these sources, adjusting the synthetic parameters in mild, solvent-free conditions. We stabilized the NixB NCs powder by probing the surface with inorganic (NOBF4) or organic (borane tert-butyl amine, oleylamine) ligands in the appropriate solvent (dimethyl sulfoxide, hexane). This method allowed the production of stable inks for further solution processing applications such as the preparation of electrodes for electrocatalytic tests. To study the inherent electrocatalytic activity of nickel borides, supported the NixB on conductive support (the carbon paper), and tested them as electrocatalysts in the reaction electrochemical oxidation of 5-hydroxymethylfurfural (5-HMF) to furan dicarboxylic acid (FDCA). Given the lack of stability of the carbon-based support under oxidative condition, our next step was to optimize the preparation and application of NixB as electrocatalyst by directly growing Ni₃B on Ni foam or Ni foil. This method is very cost efficient since it eliminates the need for additional steps to load the nickel boride electrocatalyst onto the support. Finally, we tackle an issue encountered in the practice of electrochemical oxidation of 5-HMF, contamination the anionic exchange membrane used in electrochemical setups by the undesired byproduct hummins, through the commercial cellulose-based foam as an additional separator and placing it between the electrolyte and the polymeric membrane.

Dissertation