No abstract

Streamlined architectures with a low fluid-resistance coefficient have been receiving great attention in various fields. However, it is still a great challenge to synthesize streamlined architecture with tunable surface curvature at the nanoscale. Herein, we report a facile interfacial dynamic migration strategy for the synthesis of streamlined mesoporous nanotadpoles with varied architectures. These tadpole-like nanoparticles possess a big streamlined head and a slender tail, which exhibit large inner cavities (75−170 nm), high surface areas (424−488 m 2 g −1 ), and uniform mesopore sizes (2.4−3.2 nm). The head curvature of the streamlined mesoporous nanoparticles can be well-tuned from ∼2.96 × 10 −2 to ∼5.56 × 10 −2 nm −1 , and the tail length can also be regulated from ∼30 to ∼650 nm. By selectively loading the Fe 3 O 4 catalyst in the cavity of the streamlined silica nanotadpoles, the H 2 O 2 -driven mesoporous nanomotors were designed. The mesoporous nanomotors with optimized structural parameters exhibit outstanding directionality and a diffusion coefficient of 8.15 μm 2 s −1 .

Surface redox pseudocapacitance, which enables short charging times and high power delivery, is very attractive in a wide range of sites. To achieve maximized specific capacity, nanostructuring of active materials with high surface area is indispensable. However, one key limitation for capacitive materials is their low volumetric capacity due to the low tap density of nanomaterials. Here, we present a promising mesoscale TiO 2 structure with precisely controlled mesoporous frameworks as a high-density pseudocapacitive model system. The dense-packed mesoscopic TiO 2 in micrometer size offers a high accessible surface area (124 m 2 g −1 ) and radially aligned mesopore channels, but high tap density (1.7 g cm −3 ) that is much higher than TiO 2 nanoparticles (0.47 g cm −3 ). As a pseudocapacitive sodium-ion storage anode, the precisely designed mesoscopic TiO 2 model achieved maximized gravimetric capacity (240 mAh g −1 ) and volumetric capacity (350 mAh cm −3 ) at 0.025 A g −1 . Such a designed pseudocapacitive mesostructure further realized a commercially comparable areal capacity (2.1 mAh cm −2 ) at a high mass loading of 9.47 mg cm −2 . This mesostructured electrode that enables fast sodiation in dense nanostructures has implications for high-power applications, fast-charging devices, and pseudocapacitive electrode design.

Constructing hierarchical three-dimensional (3D) mesostructures with unique pore structure, controllable morphology, highly accessible surface area, and appealing functionality remains a great challenge in materials science. Here, we report a monomicelle interface confined assembly approach to fabricate an unprecedented type of 3D mesoporous N-doped carbon superstructure for the first time. In this hierarchical structure, a large hollow locates in the center (∼300 nm in diameter), and an ultrathin monolayer of spherical mesopores (∼22 nm) uniformly distributes on the hollow shells. Meanwhile, a small hole (4.0–4.5 nm) is also created on the interior surface of each small spherical mesopore, enabling the superstructure to be totally interconnected. Vitally, such interconnected porous supraparticles exhibit ultrahigh accessible surface area (685 m2 g–1) and good underwater aerophilicity due to the abundant spherical mesopores. Additionally, the number (70–150) of spherical mesopores, particle size (22 and 42 nm), and shell thickness (4.0–26 nm) of the supraparticles can all be accurately manipulated. Besides this spherical morphology, other configurations involving 3D hollow nanovesicles and 2D nanosheets were also obtained. Finally, we manifest the mesoporous carbon superstructure as an advanced electrocatalytic material with a half-wave potential of 0.82 V (vs RHE), equivalent to the value of the commercial Pt/C electrode, and notable durability for oxygen reduction reaction (ORR).

High current density hydrogen evolution reaction (HER) in alkaline water electrolysis plays crucial role in renewable and sustainable energy systems, while posing a great challenge to the highly‐efficient electrocatalysts. Here, the synthesis of Ni/NiO@MoO3−x composite nanoarrays is reported by a moderate reduction strategy, combining Ni/NiO nanoparticles (≈20 nm) with amorphous MoO3−x nanoarrays. The Ni/NiO@MoO3−x composite nanoarrays possess enhanced hydrophilicity, optimize reaction energy barriers, accelerate reactant diffusion/bubble detachment, and therefore display an ultrahigh alkaline HER activity with a low η10 overpotential of 7 mV as well as Tafel slope of 34 mV dec−1. More significantly, the Ni/NiO@MoO3−x nanoarrays only demand low overpotentials of 75 and 112 mV to deliver 100 and 200 mA cm−2 hydrogen production current, and can steadily work at 100 mA cm−2 for 40 h, which is more efficient and stable than the Pt/C catalyst.

Poly(ε-caprolactone)/poly(lactic acid) (PCL/ PLA) blends are very promising materials with biodegradable characteristics and tailorable performance for many applications. In this study, PCL and PLA were compounded at various ratios using a co-rotating twin-screw extruder. The morphology showed that they were immiscible but were dispersed well in each other. Very interesting and peculiar open-cell structures were obtained through a batch-foaming process. Interconnected holes with flexible PCL fibrils were created by high tensile stress during cell expansion, which contributed to the rapid diffusion of CO 2 . No cells collapsed at high foam expansion under all foaming conditions. Moreover, a small-diameter tubular PCL/PLA foamed scaffold had a tensile toe region of approximately 40%, which indicated a potential application for vascular tissue engineering. The human umbilical vein endothelial cells cultured on the surfaces of PCL/PLA blend foams showed high viability and migration.

Mesoporous materials with crystalline frameworks have been acknowledged as very attractive materials in various applications. Nevertheless, due to the cracking issue during crystallization and incompatible hydrolysis and assembly, the precise control for crystalline mesoscale membranes is quite infertile. Herein, we presented an ingenious stepwise monomicelle assembly route for the syntheses of highly ordered mesoporous crystalline TiO2 membranes with delicately controlled mesophase, mesoporosity, and thickness. Such a process involves the preparation of monomicelle hydrogels and follows self-assembly by stepwise solvent evaporation, which enables the sensitive hydrolysis of TiO2 oligomers and dilatory micelle assembly to be united. In consequence, the fabricated mesoporous TiO2 membranes exhibit a broad flexibility, including tunable ordered mesophases (worm-like, hexagonal p6mm to body-centered cubic Im3̅m), controlled mesopore sizes (3.0–8.0 nm), and anatase grain sizes (2.3–8.4 nm). Besides, such mesostructured crystalline TiO2 membranes can be extended to diverse substrates (Ti, Ag, Si, FTO) with tailored thickness. The great mesoporosity of the in situ fabricated mesoscopic membranes also affords excellent pseudocapacitive behavior for sodium ion storage. This study underscores a novel pathway for balancing the interaction of precursors and micelles, which could have implications for synthesizing crystalline mesostructures in higher controllability.

As an important branch of anisotropic nanohybrids (ANHs) with multiple surfaces and functions, the porous ANHs (p-ANHs) have attracted extensive attentions because of the unique characteristics of high surface area, tunable pore structures and controllable framework compositions, etc. However, due to the large surface-chemistry and lattice mismatches between the crystalline and amorphous porous nanomaterials, the site-specific anisotropic assembly of amorphous subunits on crystalline host is challenging. Here, we report a selective occupation strategy to achieve site-specific anisotropic growth of amorphous mesoporous subunits on crystalline metal–organic framework (MOF). The amorphous polydopamine (mPDA) building blocks can be controllably grown on the {100} (type 1) or {110} (type 2) facets of crystalline ZIF-8 to form the binary super-structured p-ANHs. Based on the secondary epitaxial growth of tertiary MOF building blocks on type 1 and 2 nanostructures, the ternary p-ANHs with controllable compositions and architectures are also rationally synthesized (type 3 and 4). These intricate and unprecedented superstructures provide a good platform for the construction of nanocomposites with multiple functionalities and understanding of the structure-property-function relationships.