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.