Preparation of macroporous transition metal hydroxide monoliths via a sol-gel process accompanied by phase separation

Abstract

three-dimensional transition metal hydroxide monoliths were facilely fabricated by a sol-gel process accompanied by phase separation in the presence of polyacrylic acid (pAA) and propylene oxide (po). in the typical Zncl 2 -pAA-po system, pAA is used as a phase separation inducer as well as a framework former to control the phase separation and the formation of macrostructures, whereas po works as a proton scavenger to initiate the gelation of the system and freeze the macrostructures. Appropriate amount of pAA, po and solvents allow the formation of zinc (Zn) hydroxide monolith with cocontinuous skeletons and interconnected macropores, and the construction mechanism and characteristics of macrostructure are also investigated. the resultant dried gels are amorphous Zn hydroxide monolith with a narrow macropore size distribution (~1 μm). this approach is further used to successfully prepare macroporous single or binary composite transition metal hydroxide monoliths.

A tris-tetrazole based nanostructured soft material: studies on self-healing, AIEE, and rheological and fluorometric detection of 3-aminopyridine

“…10). The FE-SEM images revealed that the morphology in all the cases is changed upon conversion from a gel to a xerogel 53,54 (Fig. S29-S32, ESI †).…”

Macroporosity Control by Phase Separation in Sol-Gel Derived Monoliths and Microspheres

“…Transition metal hydroxide porous monoliths have also been developed recently (Table 4), in the presence of PO and HPAA [96], involving low-valence elements (Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Zn 2+ ). Inorganic metal-salts were employed in this case, which undergo hydrolysis to form hydrated metal ions complexes with water molecules.…”

“…Figure 17 displays the pore morphology obtained for varied transition metal hydroxide monoliths synthesized by the epoxide method. The effect of varied synthesis parameters was studied in this work [96]. Larger amounts of water promote the hydrolysis reaction of the Zn precursor and, therefore, an increased number of OH groups at the surface of the oligomers, establishing strong H bonds with HPAA, delaying phase separation, and resulting in finer phase-separated domains.…”

“…While for Ni 2+ and Co 2+ and Zn 2+ and Fe 2+ system, of low difference in hydrolysis rate (0.9 and 0.7), binary macroporous transition metal composites were possible to obtained via the sol-gel process accompanied by phase separation. Transition metal hydroxide porous monoliths have also been developed recently (Table 4), in the presence of PO and HPAA [96], involving low-valence elements (Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Zn 2+ ). Inorganic metal-salts were employed in this case, which undergo hydrolysis to form hydrated metal ions complexes with water molecules.…”

Tunable and Well-Defined Bimodal Porous Model Electrodes for Revealing Multiscale Structural Effects in the Nonaqueous Li–O2 Electrode Process

“…The sol–gel process accompanied by phase separation was first reported in the silica system in 1991, and various kinds of metal hydroxide and oxide monoliths have been reported . Some researchers reported nickel hydroxide/poly­(acrylic acid) composite monoliths via the phase separation route. − However, a large amount of the organic polymer, poly­(acrylic acid), in the skeletons is difficult to be removed without collapsing the macroporous structures and monolithic forms . Until now, the phase separation approach toward macroporous low-valence metal hydroxide monoliths has not been successfully prepared without the contamination of a large amount of the organic polymer in the metal hydroxide skeletons. − Therefore, a synthetic strategy which enables to avoid the contamination of the organic polymer in the skeletons is needed to obtain the pure metallic nickel monolithic electrodes with controlled multiscale porous structures.…”