Hierarchically porous carbon materials with interconnected frameworks of macro- and mesopores are desirable for electrochemical applications in biosensors, electrocatalysis, and supercapacitors. In this study, we report a facile synthetic route to fabricate hierarchically porous carbon materials by controlled macro- and mesophase separation of a mixture of polystyrene-block-poly­(ethylene) and dopamine. The morphology of mesopores is tailored by controlling the coassembly of PS-b-PEO and dopamine in the acidic tetrahydrofuran–water cosolvent. HCl addition plays a critical role via enhancing the charge–dipole interactions between PEO and dopamine and suppressing the clustering and chemical reactions of dopamine in solution. As a result, subsequent drying can produce interpenetrated PS-b-PEO/DA mixtures without forming dopamine microsized crystallites. Dopamine oxidative polymerization induced by solvent annealing in NH4OH vapor enables the formation of percolating macropores. Subsequent pyrolysis to selectively remove the PS-b-PEO template from the complex can produce hierarchically porous carbon materials with interconnected frameworks of macro- and mesopores when pyrolysis is implemented at a low temperature or when DA is a minor component.

Functional nitrogen-doped hierarchically porous carbon materials (NHPCMs) have received much attention in recent years because of their electrochemical and catalytic activities, which offer potential applications in the field of fuel cells. Herein we demonstrate the NHPCMs with superior performance of the oxygen reduction reaction (ORR) through spontaneous coassembly of polystyrene-block-poly­(ethylene oxide) (PS-b-PEO) micelles along with self-polymerization of dopamine (DA). In this study, we aim to deeply understand the effects of HCl addition, DA content, and aging environment on morphologies of NHPCMs through studying self-assembly and phase behavior of PS-b-PEO/DA mixtures in cosolvent using synchrotron small-angle X-ray scattering and transmission X-ray microscopy. The morphology of hierarchical pores can be successfully obtained by fine controls over DA content and pyrolysis temperature. Correlations of morphologies and processes with the ORR performance indicate that hierarchically porous carbon materials exhibit the highest ORR performance with J k = 8.1 mA cm–2 (measured at −0.4 V of SCE), low onset potential η = −0.11 V, and four-electron transfer pathway over a wide voltage range.

Bowl-like nanostructures have attracted significant scientific and technological interest due to their favorable characteristics, such as high specific surface area, interconnected porous channels, and conductivity. However, tailored synthesis of bowl-like nanostructures with well-defined and uniform morphology is still a challenge. Herein, we report a versatile microemulsion assembly approach to prepare bowl-like nanostructures of three different materials: polymer, carbon, and platinum. To this end, polystyrene-block-poly(4vinylpyridine), PS-b-P4VP, block copolymer (BCP) microparticles with truncated-sphere shape and composed of stacks of parallel lamellae were used because those anisotropic microparticles play an important role in the design of bowl-like nanostructures. To form nanolamellae-within-microparticle morphology, a designed PS-b-P4VP/chloroform/CTAB microemulsion can be facilely obtained in the aqueous medium, where the morphology can be tailored by the interplay between macro-phase separations, BCP self-assembly, and interfacial energies of three phases in the presence of cetyltrimethylammonium bromide (CTAB). Finally, protonation or combination of cross-linking and pyrolysis of those truncated microparticles enables formation of polymer or carbon bowl-like nanostructures, respectively. Upon selective adsorption of Pt precursor salt ions with the pyridyl moieties followed by chemical reduction, subsequent calcination permits the synthesis of Pt bowl-like nanostructures. The microemulsion assembly approach opens up new ways to direct and template bowl-like nanostructures.

This study aims to quantitatively investigate the effect of water content on the self-assembly behavior of polystyreneblock-poly(ethylene oxide) (PS-b-PEO) in tetrahydrofuran/water cosolvents by small-angle X-ray scattering. PS-b-PEO chains preferentially form fractal aggregates at a dilute concentration in neat tetrahydrofuran (THF). By adding a small amount of water into THF, PS-b-PEO forms gelled networks. The gelled networks have correlated inhomogeneities, which were generated through mesophase separation. These gelled networks are not present when PS-b-PEO is dissolved in THF/methanol and THF/ethanol cosolvents. The substitution of water with 12 M HCl reduces the viscosity of the gelled networks. Those results indicate that the gelled networks of PS-b-PEO need hydrogen bonds formed from surrounding water molecules to be bridging agents, which connect different PEO block chains together. Upon increasing the water content in THF/water cosolvents, dispersed micelles with a core− shell conformation or aggregated micelles preferentially coexist with fractal aggregates.

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