| Layered double hydroxides (LDH) containing NiAl or NiV of varying M(II):M(RI) (2:1, 5:1, 9:1 for NiAl and 2:1, 5:1 for NiV) ratios have been prepared by coprecipitation and characterized by XRD, elemental analysis, and FT-IR. The LDHs electrochemical properties were investigated in half-cells to determine their potential application as positive electrode in Ni-Cd and NiMH batteries. The Ni2Al LDH exchanges the most electrons (up to 1.6) and is the most stable during discharging in the KOH electrolyte. The large quantity of electrons and accrued stability was attributed to the aluminium in the layers acting in a two fold manner: High charge to radius ratio increased the electrostatic interaction between the anions and the metal layers increasing the stability of the LDHs and the increase in Brønsted acidity of the hydroxyl groups was accredited for the high exchange of electrons. Notwithstanding the high exchange of electrons of the NiAl LDHs the powders exhibit lower discharge capacity compared to commercial electrode material (β-Ni(OH) 2) due to their low density.; The NiV LDHs only exchanged up to 1.2 electrons (Ni2V) and were found only stable up to a maximum of 14 days in electrolytic solutions of the cells.; In the second part of the study ZnAl LDHs were synthesized and intercalated with phenyl phosphonic acid (PPA) or 1,4-phenylene bis phosphonic acid (B-PPA) in order to create microporous materials. The compounds were characterized by XRD, chemical, IR and solid state NMR analysis in addition to being tested for microporosity. The ZnAl LDHs treated with phenyl phosphonic acid gave rise to materials with a d spacing of 14.7Å and when treated to B-PPA resulted in materials with a d spacing of 9.6 Å. The results showed that the grafting of both phosphonates to the metal layers had occurred. The d spacing of 14.7 Å was interpreted as being due to a bilayer of PPA molecules in head to head configuration in the layers. The d spacing of 9.6 Å was consistent with a monolayer of B-PPA molecules cross-linking the metal layers of the material. Both materials exhibited little or no microporosity due to the “packing” of the phosphonate moieties in the layers.; The last section of the thesis consisted of attempting to synthesize MCM or FSM type molecular sieves by the treatment of ZnAl LDH with hexadecane sulfonic acid or sodium dodecyl sulfate used as templates under different reaction conditions. The materials were characterized by XRD, chemical analysis and IR analysis. The results were consistent with LDHs intercalated with either a monolayer or a bilayer arrangement of surfactant molecules and therefore did not exhibit MCM or FSM mesoporous frameworks. |
