| In this thesis, both surfactant and solid-colloidal templating methods have been applied to synthesize various mesoporous materials with electrochemical functionalities. Further, macroporous material has also been prepared using solid-colloidal templating. Critical properties of mesoporous materials as the electrodes for fuel cells and lithium ion batteries, and as the sensing elements for gas sensors, have been studied. Firstly, mesoporous SnO2 thermally stable up to 500°C has been synthesized using both neutral and cationic surfactants as structure-directing agents. Further, mesoporous SnO2 thermally stable up to 600°C has been synthesized using ordered mesoporous silica as template. A CO2 sensor based on mesoporous SnO2 obtained using silica as template exhibits fast and reproducible responses tested at 500°C. Secondly, mesoporous SnO 2-SiO2 composite has been prepared. Good cycleability and a relatively high reversible capacity have been achieved in this work when mesoporous SnO2-SiO2 composites are tested as anodes for lithium ion batteries. Thirdly, mesoporous YSZ and YSZ-NiO composite thermally stable up to 500°C have been prepared using a tri-block compolymer as the structure-directing agent. Using an anionic surfactant as the structure-directing agent, the stability of the YSZ and YSZ-NiO mesostructures has been extended to 600°C. Mesoporous YSZ showed high sinterability and could be sintered to dense YSZ pellets at 1250°C with a relative density of 94%. Using mesoporous YSZ-NiO as anode for YSZ electrolyte, the anode/electrolyte interfacial resistances are 9.6, 5.8, 2.8 Ωcm2 at 500, 550, and 600°C, respectively. Finally, ordered macroporous Sr0.5Sm0.5CoO3 structures with an average pore size of 140 nm were prepared using polystyrene spheres as templates. A fuel cell using ordered macroporous Sr0.5Sm 0.5CoO3 as the cathode, gadolinia-doped ceria (GDC) film as the electrolyte, and GDC-NiO as the anode generated maximum power densities of 150, 196 and 267 mW/cm2 at 500, 550 and 600°C, respectively. |
