Ice-templating was performed by pouring 10 ml of slurry into a PTFE mold (20 mm diameter and 25 mm height) placed on top of a copper plate and freezing from the bottom to the top. The temperature was controlled by circulating silicone oil regulated by a cryothermostat (Model CC 905, Hubert, Offenburg, Germany) through the copper plate. The cooling rate was set at 2 • C/min. After complete solidification, samples were demolded and freeze-dried for at least 48 hrs in a commercial freeze-dryer (Free Zone 2.5 Plus, Labconco, Kansas City, Missouri, USA).