Direct Ink Writing of Multifunctional Silica-Reinforced Zirconia Aerogels via Electrostatic Attraction-Assisted Co-Gelation

ZrO2 aerogels are renowned for their exceptional stability and high positive charge, positioning them as promising candidates for various applications. However, the inherent frangibility and contractibility of ZrO2 aerogels pose significant challenges in processing and drying intactly. In this study, we introduce a novel approach to fabricate 3D-printed ZrO2-based aerogels through electrostatic attraction-assisted cogelation process, utilizing a silica reinforcement and rheological adjustment strategy. Under the dispersion and coordination effects of a silica sol with opposite charges, crack-free 3D-printed ZrO2-based aerogels were successfully prepared. These 3D-printed samples exhibit a low filament density of 221 mg cm-3 and an impressive specific surface area of up to 535.6 m2 g-1, showcasing superior performance in high-temperature insulation (withstanding temperature up to 1300 °C) and phosphate adsorption (with an adsorption capacity reaching 88.78 mg g-1). It is revealed that incorporated SiO2 is uniformly dispersed even at the primary structure level, forming a homogeneous hybrid skeleton. The zeta-potential results indicate that the uniform dispersion is due to the electrostatic attraction between positively charged ZrO2 sol and negatively charged SiO2 sol during the cogelation process. This innovative strategy paves the way for the development of ceramic-based inks suitable for 3D printing applications.