Synthesis of Zirconia with Nanoporous Structure by a Supercritical Carbon Dioxide Microemulsion Route

Supercritical carbon dioxide (scCO 2 ) fluid as a green solvent for processing can markedly reduce the use of organic solvents. Nanoporous clusters of zirconia (ZrO 2 ) were synthesized in a [Zr 4+ ]( aq )/scCO 2 microemulsion using hydrazine solution as the precipitating agent, and the resulting nanostructures (surface area, morphology) under different reaction temperatures and pressures were determined by BET and TEM. The inter droplet separation of microemulsions increases with the reaction pressure at a fixed temperature, giving different networked nanostructures. The closed pore diameters were in the range of 5–150 nm (mesopores and macropores) at 17.3 MPa and 80°C.