ACS Nanoscience Au最新文献

Boron nitride nanotubes (BNNTs) are a promising nanomaterial due to their remarkable optical and mechanical properties, chemical robustness, and extended aspect ratios. Herein, we report the formation of strongly biaxially aligned thin films of BNNTs using automated slow vacuum filtration (SVF), as well as their cocomposites with single-wall carbon nanotubes (SWCNTs). Pure BNNT SVF-generated films are found to differ in optimization conditions from those identified previously for SWCNTs but display similar improvements in alignment and uniformity with advanced purification for nanotube length and homogeneity, with globally aligned films observed. Mixed, cocomposite, biaxially aligned films of BNNTs with SWCNTs are also described. Such films provide effective and efficient hosting capabilities for unique morphologies of distributed and individualized SWCNTs aligned by a wide-bandgap BNNT matrix. Concentrations upward of 25% SWCNT mass fraction were found to reside within majority-BNNT films without significantly disrupting the global composite structure; the SWCNT fraction, in turn, enabled probing of both local and global nematic alignment through their use as spectroscopic reporters. Leveraging the thickness and alignment control provided by our SVF implementation, both neat BNNT and composite films show great promise for advancing novel photonic and other thin-film nanocomposite applications requiring tailorable mechanical, thermal, optical, and electronic functionalities.

Lead halide perovskite (LHP) nanocrystals have demonstrated a significant electronic response to their local environment due to their ionic lattice nature. Here, we demonstrated their tunable dipole alignment via solution-processed methods. We synthesized LHP nanocubes and nanoplates in air and characterized them by UV–vis spectrophotometry and transmission electron microscopy. Using atomic force microscopy, UV–vis spectrophotometry, and back focal plane fluorescence microscopy, we characterized thin films of nanocubes on untreated glass, nanoroughened glass, and polymer film (poly(methyl methacrylate), PMMA), as well as a perovskite nanocubes-nanoplate binary film on etched glass. Most notably, the dipole orientation factor can be modulated from 0.47 to 0.59 (effective transition dipole moment angle from 47° to 40°) by using glass or PMMA, respectively. Understanding the tunable anisotropic transitions in these materials at the nanoscale is required to control light emission into specific modes, which will maximize efficiency in devices such as light-emitting diodes, photovoltaics, and quantum information technology.

This study investigates the photocatalytic performance of Cu₂O surfaces modified with halogen-substituted phenylacetylenes (4-XA), including 1-ethynyl-4-fluorobenzene (4-FA), 1-chloro-4-ethynylbenzene (4-CA), and 1-bromo-4-ethynylbenzene (4-BA), using an integrated theoretical and experimental approach. Through density functional theory (DFT) calculations and ultraviolet photoelectron spectroscopy (UPS) measurements, we analyze how these molecular decorators affect charge transfer dynamics and the electronic structure of the Cu₂O {100}, {110}, and {111} facets. Two distinct photocatalytic mechanisms are proposed: one where electrons reach the vacuum level through the molecular decorator and another where electrons escape directly through the Cu₂O surface via molecular-induced hybridized states. Our results show that 4-BA-modified {100} surfaces exhibit the strongest enhancement, which is attributed to the presence of in-gap molecular states, increased charge separation, and a significantly reduced work function. Experimental degradation of methyl orange validates the trend 4-BA > 4-CA > 4-FA, consistent with theoretical predictions. These findings highlight the crucial role of band structure engineering and provide guidelines for the rational design of high-performance molecularly decorated photocatalysts.

Template-stripped substrates provide on-demand access to clean, ultraflat gold surfaces, avoiding the need for laborious cleaning procedures or the use of expensive single-crystal electrodes. While these gold/adhesion layer/support sandwich structures are most conveniently prepared through the application of epoxy or optical adhesives, such composites exhibit instabilities in organic solvents that limit their wider application. Here we demonstrate that substrates with solvent-impermeable metal films can be used in previously problematic chemical environments after integration into a protective, custom-built (electrochemical) flow cell. We apply our methodology to probe different self-assembled monolayers, observing reproducible alkanethiol reductive desorption features, an exemplary redox response using 6-(ferrocenyl)hexanethiol, and corroborate findings that cobalt(II) bis(terpyridine) assemblies exhibit a low coverage. This work significantly extends the utility of these substrates, relative to mechanically polished or freshly deposited alternatives, particularly for studies of systems involving adsorbed molecules whose properties are strongly influenced by the nanoscopic features of the metal-solution interface.