We demonstrate an unusual electrochemical reaction of sulfur with lithium upon encapsulation in narrow-diameter (sub-nanometer) single-walled carbon nanotubes (SWNTs). Our study provides mechanistic insight on the synergistic effects of sulfur confinement and Li + ion solvation properties that culminate in a new mechanism of these sub-nanoscale-enabled reactions (which cannot be solely attributed to the lithiation-delithiation of conventional sulfur). Two types of SWNTs with distinct diameters, produced by electric arc (EA-SWNTs, average diameter 1.55 nm) or high-pressure carbon monoxide (HiPco-SWNTs, average diameter 1.0 nm), are investigated with two comparable electrolyte systems based on tetraethylene glycol dimethyl ether (TEGDME) and 1,4,7,10,13-pentaoxacyclopentadecane (15-crown-5). Electrochemical analyses indicate that a conventional solution-phase Li-S reaction occurs in EA-SWNTs, which can be attributed to the smaller solvated [Li(TEGDME)] + and [Li(15-crown-5)] + ions within the EA-SWNT diameter. In stark contrast, the Li-S confined in narrower diameter HiPco-SWNTs exhibits unusual electrochemical behavior which can be attributed to a solid-state reaction

Precise identification and in-depth understanding of defects in nanomaterials can aid in rationally modulating defect-induced functionalities. However, few studies have explored vacancy defects in ligand-stabilized metal nanoclusters with well-defined structures, owing to the substantial challenge of synthesizing and isolating such defective metal nanoclusters. Herein, a novel defective copper hydride nanocluster, [Cu 36 H 10 (PET) 24 (PPh 3 ) 6 Cl 2 ] (Cu36; PET: phenylethanethiolate; PPh 3 : triphenylphosphine), is successfully synthesized at the gram scale via a simple one-pot reduction method. Structural analysis reveals that Cu36 is a distorted half cubic nanocluster, evolved from the perfect Nichol's half cube. The two surface copper vacancies in Cu36 are found to be the principal imperfections, which result in some structural adjustments, including copper atom reconstruction near the vacancies as well as ligand modifications (e.g., substitution, migration, and exfoliation). Density functional theory calculations imply that the above-mentioned defects have a considerable influence on the electronic structure and properties. The modeling suggests that the formation of defective Cu36 rather than the perfect half cube is driven by the enlargement of the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the nanocluster. The structural evolution induced by the surface copper atom vacancies provides atomically precise insights into the defect-induced readjustment of the local structure and introduces new avenues for understanding the chemistry of defects in nanomaterials.

Research on the synthesis of mesoporous materials has mainly focused on mesostructural diversity, [1][2][3][4] compositional flexibility, [5][6][7][8] and morphological control. [9][10][11][12] The ability to obtain mesoporous particles with a controlled particle size would be important for many practical applications. For example, ultrafine mesoporous particles would be very useful in catalysis and gas adsorption, since they would provide greater pore accessibility and facilitate molecular diffusion. They could also act as the host matrix for the synthesis of quantum dots and magnetic nanoparticles in functional materials and bio-imaging applications.[13] Ultrafine mesoporous particles could also act as carriers for drugs, genes, and proteins for novel biomedical applications. [14,15] Some examples of ultrafine mesoporous particles have been sporadically reported, [16][17][18][19][20][21][22][23] but the type of mesostructure, the degree of structural ordering, and the range of pore sizes are limited. Herein we describe a simple wet-chemical method that enables the synthesis of nanometer-sized particles (50-300 nm) with tunable pore sizes in the range 5-30 nm. This fluorocarbon-surfactant-mediated synthesis can be generalized to achieve various pore structures, including 3D cubic Im3 m, 3D cubic Fm3 m, 2D hexagonal p6m, foamlike, and disordered pores, as well as different material compositions.Our syntheses were carried out in a weakly acidic medium (pH 1.6-1.8), in which a homogeneous solution was formed by mixing a soluble silica precursor, a nonionic triblock copolymer surfactant EO x PO y EO x (EO = ethylene oxide, PO = propylene oxide), and the cationic fluorocarbon surfactant

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