Crystalline ZrO₂ Monoliths with Well-Defined Macropores and Mesostructured Skeletons Prepared by Combining the Alkoxy-Derived Sol–Gel Process Accompanied by Phase Separation and the Solvothermal Process

Abstract

We have successfully prepared multiscale porous crystalline zirconia (ZrO2) monoliths by combining the alkoxy-derived sol–gel process accompanied by phase-separation and the solvothermal process. The gelation can be controlled by the addition of N-methylformamide to the starting solution, while the phase separation is induced by the incorporation of poly(ethylene oxide). Amorphous ZrO2 monolithic gels with well-defined bicontinuous macropores and microstructured skeletons are obtained when the transient structure of polymerization-induced phase separation is fixed by the gelation. The size of the macropores is controlled in the range of 300 nm to 2 µm by adjusting the amount of poly(ethylene oxide). The solvent exchange of the mother liquor in the as-gelled wet specimens with absolute ethanol, followed by the solvothermal treatment at temperatures above 210 °C, brings about the formation of mesopores and stabilizes tetragonal ZrO2 nanocrystals without disturbing the macroporous morphology. The resultant macro-mesoporous crystalline ZrO2 gels possess the surface area over 200 m2 g−1.

Design of hierarchically meso–macroporous tetragonal ZrO2 thin films with tunable thickness by spin-coating via sol–gel template route

“…On the other hands, surfactant-templated strategies allow the fabrication of hierarchically meso-macroporous ZrO 2 [47,[57][58][59].…”

“…Two years later, Chen et al [47] prepared hierarchically porous ZrO 2 via dual non-ionic surfactants templating method. The reported resultant ZrO 2 in the works of [47,[57][58][59] was in the form of powders or monolith. To the best of our knowledge, the hierarchically mesomacroporous ZrO 2 prepared in thin films has not been achieved hitherto.…”

A Cost‐Effective Supercapacitor Material of Ultrahigh Specific Capacitances: Spinel Nickel Cobaltite Aerogels from an Epoxide‐Driven Sol–Gel Process

“…Alkoxides are generally expensive and sensitive to moisture and heat, requiring careful handling. [19][20][21][22] Recently, to tackle these drawbacks, the epoxide synthetic route, enabling the use of low-cost and stable metal salts as the precursors, was successfully developed to prepare metal oxide aerogels. [23][24][25][26] In this work, we reported the first successful preparation of nickel cobaltite aerogels with the epoxide-driven sol-gel process.…”

Development of Non-Siliceous Porous Materials and Emerging Applications

“…The synthesis strategy developed for alkoxy-derived TiO 2 systems is applicable to the preparation of macroporous ZrO 2 monoliths. 48 In this subsection, the results concerning the macropore formation are briefly presented. The effects of postgelation treatment on mesoporous structures and crystallinity are also described.…”