Aerobijels: Ultralight Carbon Monoliths from Cocontinuous Emulsions

Abstract

Bijels are used to develop a new class of ultralight hierarchically porous aerogels exhibiting multimodal porosity across multiple length scales. Through in situ functionalization of a particle-laden liquid interface wherein binary liquid pairs are kinetically trapped out of equilibrium through interfacial jamming, monolithic and freestanding carbon electrodes are produced with prescribed bulk densities down to ≈2 mg cm −3 . Exemplary electrokinetic experiments indicate that the bicontinuity of the pore structure is essential for enhancing transport to and from the active electrode surfaces, demonstrating that these materials possess a superior ability to accumulate and transport charge when compared to analogous systems with restricted pore connectivity and fluid throughput. This approach offers a new synthetic route to bicontinuous and hierarchical aerogel materials with nested multimodal porosities. The flexibility of this scheme can address critical issues related to transport-limited behaviors that arise in many technological fields, ranging from energy and catalysis research to remediation and sensing applications.

Nanostructured, Fluid‐Bicontinuous Gels for Continuous‐Flow Liquid–Liquid Extraction

“…This explains why STrIPS facilitates the use of nanoparticles to stabilize the interwoven fluids, enabling submicrometer channel sizes, while thermally induced phase separation (TIPS) requires larger colloidal particles, thereby limiting the smallest possible channel dimensions. [6,11,15] Why did previous studies on STrIPS not introduce the formation of sub-micrometer sized channels throughout the entire bijel structure? [17] Here, we can reproduce the structure of a typical STrIPS bijel by employing 2-propanol as the solvent.…”

“…[1][2][3][4] Fluid-bicontinuous gels are kinetically arrested colloidal gels that facilitate intimate contact between two immiscible liquids, while each liquid remains fully interconnected. [5,6] Recently, these structures have been employed for the fabrication of separation membranes, [7] microreactors, [8] sensors, [9] energy-storage devices, [10] carbon monoliths, [11] microropes, [12] and tissue engineering scaffolds. [13] However, limited Here, we present the successful production of bijels with internal sub-micrometer domains of the smallest pore sizes yet reported via a continuous and scalable synthesis method based on STrIPS and the realization of fluid flow through these bijels.…”

“…[ 1–4 ] Fluid‐bicontinuous gels are kinetically arrested colloidal gels that facilitate intimate contact between two immiscible liquids, while each liquid remains fully interconnected. [ 5,6 ] Recently, these structures have been employed for the fabrication of separation membranes, [ 7 ] microreactors, [ 8 ] sensors, [ 9 ] energy‐storage devices, [ 10 ] carbon monoliths, [ 11 ] microropes, [ 12 ] and tissue engineering scaffolds. [ 13 ] However, limited control over their history dependent formation process and the inability to flow liquids through them has restricted their potentials until now.…”

“…[14] Most frequently, spinodal decomposition is initiated by changing the temperature of a solution of two partially miscible liquids containing dispersed colloids. [6,9,11] However, the interfacial tension between fluids undergoing thermally-induced spinodal decomposition is not high enough to be able to employ nanoparticles (<100 nm) as interfacial stabilizers because their interfacial binding energy is too low. Instead, larger colloidal particles (>200 nm) are needed, resulting in fluid-bicontinuous gels with micrometersized fluid domains (>5 µm).…”

Bicontinuous soft solids with a gradient in channel size designed for energy storage applications

“…The bicontinuous structure and large interfacialarea-to-volume ratio of bijels make them promising candidates for use in novel energy materials, especially since they can be (post)-processed to allow the initial fluid channels to be replaced with other materials [6,7,8,9,10,11]. For example, Lee et al have used water-lutidine bijels as scaffolds to synthesise porous gold monoliths [12], while Mohraz et al have developed three-dimensional Ni/Ni(OH) 2 composite electrodes [13] and ZnO electrodes [14].…”