Preparation of hierarchically porous spinel CoMn 2 O 4 monoliths via sol–gel process accompanied by phase separation

• Published in: Journal of the American Ceramic Society Vol. 104; no. 6; pp. 2449 - 2459
• Main Authors: Lu, Xuanming, Kanamori, Kazuyoshi, Hasegawa, George, Nakanishi, Kazuki
• Format: Journal Article
• Language: English
• Published: 01.06.2021
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.17662

Abstract Cobalt manganite‐based hierarchically porous monoliths (HPMs) with three‐dimensionally (3D) interconnected macropores and open nanopores have been prepared via the sol–gel process accompanied by phase separation. The controlled hydrolysis and polycondensation of the brominated metal alkoxides, which are generated from an incomplete reaction between epichlorohydrin and M Br 2 ( M = Co and Mn) in N , N ‐dimethylformamide (DMF), form a monolithic gel based on the two divalent metal cations. The dual‐polymer strategy using polyvinylpyrrolidone (PVP) and poly(ethylene oxide) (PEO) effectively induces the spinodal decomposition, where PVP and PEO are preferentially distributed to the gel phase and fluid phase, respectively, resulting in a porous gel characterized by the co‐continuous structure. The effects of DMF and PVP on the porous morphology derived from the phase separation have been systematically studied. Calcination of the as‐dried gels allows for the crystallization into the spinel phase yielding hierarchically porous CoMn 2 O 4 monoliths, which have been examined in detail by the structural and compositional analyses.