ACS Materials Letters最新文献

Here, we report the discovery of the first (8,8)-connected three-dimensional (3D) covalent organic framework (COF), TUS-88, having bcu topology by linking an 8-connected D_4h-symmetric quadrangular prism node to an 8-connected D_2h-symmetric tetragonal prism node. Derived from the π-aromatic conjugated system of pyrene and the abundant aromatic phenyl rings composing the COF scaffold, which promotes stronger π···π interactions with aromatic benzene (Bz) molecules, a superlative Bz uptake of 464 cm³ g^–1 was achieved for TUS-88, coupled with exemplary cyclohexane (Cy) uptake of 224 cm³ g^–1 and ideal Bz/Cy selectivity of 2.07 which are the current benchmark. Breakthrough experiments accomplished using a Bz/Cy (1:1, v/v) mixture corroborated the preferential adsorption of Bz by the COF from the mixture to generate high-purity Cy with a significant time interval of 75.4 min g^–1 and a record-setting Bz/Cy breakthrough selectivity of 2.46.

Polarimetric phototransistors have attracted increasing interest due to their ability to recognize the polarization state of incident linearly polarized light. However, advances in their development have been hindered by the low polarization sensitivity that results from the modest polarization dichroic ratios (PDRs) of the photoactive materials. In this study, we present polarimetric organic phototransistors (P-OPTs) with a remarkably high polarization sensitivity exceeding 8.0. These P-OPTs are fabricated by transferring highly stretched (∼200%) thin films of a polymer semiconductor, poly(4-(5-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-octyl-7-(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole) (PCDTFBTA), which exhibits a high PDR of approximately 4.0. This improved polarization sensitivity ranks among the highest sensitivities reported for polarimetric phototransistors, demonstrating high photoresponsivity (R ≈ 500 A W^–1), high external quantum efficiency (EQE ≈ 1000%), high photosensitivity (P ≈ 1.8 × 10⁴), high specific detectivity (D* ≈ 5.9 × 10¹² Jones), and short rise (τ_r ≈ 3.3 ms) and decay (τ_d ≈ 3.4 ms) times.

Here we report the self-assembly of 3D perovskites and 2D layered perovskites into large core–shell heterocrystals with well-defined interfaces and a controlled shell thickness. The 3D core possesses desirable X-ray responsive optoelectronic properties, while the hydrophobic organic spacers in the 2D shell can suppress ion migration and prevent the direct exposure of the core to moisture. Notably, X-ray detectors using these core–shell heterocrystals exhibit ultralow dark current drift of 1.1 × 10^–7 nA cm^–1 s^–1 V^–1, which is 5 orders of magnitude lower than that of the pristine 3D perovskite devices. Moreover, the devices also display significantly enhanced X-ray response, including high sensitivity of 1 × 10⁴ μC Gy_air^–1 cm^–2, low detection limit of 40 nGy_air s^–1, and the capacity for high-resolution X-ray imaging. By realizing core–shell heterocrystals, this work paves the way for developing high-performance perovskite optoelectronic devices with high stability and sensitivity.

Carbon-based hole-conductor-free perovskite solar cells (PSCs) exhibit promising potential on the road to commercialization for their low-cost production, scalable fabrication, and superior stability. However, the insufficient back interface contact between the carbon counter electrode (CE) and the perovskite is an urgent issue that hinders device performance. Herein, we report the preparation and application of defect-rich boron-doped graphite (BG) as the main CE medium for efficient printable mesoscopic PSCs (p-MPSCs). Boron doping induces the formation of abundant defective sites, including dangling bonds and oxygen-containing groups, onto the surface of graphite. These sites activate the inert surface and improve the surface affinity of CE with the perovskite. p-MPSCs based on BG achieve a firm interfacial contact, which improves the power conversion efficiency from 17.94% to 19.43% by enhancing charge collection.

Supramolecular nanotubes constructed from the self-assembly of conjugated metal–organic macrocycles provide a unique collection of materials properties, including solution processability, porosity, and electrical conductivity. Here we show how small modifications to the macrocycle periphery subtly alter the noncovalent interactions governing self-assembly, leading to large changes in crystal packing, crystal morphology, and materials properties. Specifically, we synthesized five distinct copper-based macrocycles that differ in either the steric bulk, polarity, or hydrogen-bonding ability of the peripheral side chains. We show that the electrical conductivity of these macrocycles is highly sensitive to steric bulk, decreasing by 3 orders of magnitude upon introduction of peripheral neopentyl substituents. We further show that the introduction of hydrogen-bonding groups leads to more ordered packing and a dramatic increase in crystallite size. Together, these results establish side-chain engineering as a rich toolkit for controlling the packing structure, particle morphology, and bulk properties of conjugated metal–organic macrocycles.

The Volmer–Tafel (VT) and Volmer–Heyrovsky (VH) mechanisms were believed to be determined solely by the proximity of adsorbed hydrogen atoms on metallic surfaces for the hydrogen evolution reaction (HER). However, recent investigations challenge this notion, particularly with catalysts such as Au and Ag, where VH pathways are observed despite the close hydrogen atom distance. This study investigates the influence of free energy on hydrogen adsorption (ΔG_H^*) and active site density on HER pathways, incorporating the consideration of the rate-determining step (RDS). Contrary to previous assumptions, it is found that ΔG_H^* plays a pivotal role, with VT pathways favored when ΔG_H^* approaches zero, and while VH pathways occurs in other cases, irrespective of active site density. This inclusive analysis, integrating both thermodynamic and energetic considerations with experimental and theoretical support, sheds new light on the mechanistic intricacies of the HER, challenging conventional paradigms and providing insights that are crucial for catalyst design.

Developing ruthenium-based (Ru-based) catalysts with a heterointerface is essential to improving the acidic oxygen evolution reaction (OER) performance. In this study, we first prepared RuO₂/CoMnO₃ nanosheet catalysts by solid-phase pyrolysis, featuring a low Ru content, and presented a high OER mass activity (1742.9 A g_Ru^–1 at 1.53 V) and superior stability (500 h at 10 mA cm^–2) in 0.5 M H₂SO₄ under a three-electrode system. Notably, Co and Mn sites facilitated electron transfer to Ru sites through bridge oxygen to avoid Ru overoxidation, as proved by the increase in the average surface oxidation state (SOS) of Mn and Co and the insignificant change in the average SOS of Ru after the chronopotentiometry test. Moreover, the heterointerface can reduce the OER energy barrier and restrain the participation of lattice oxygen. This work indicates the significant potential of employing well-supported catalysts with an adjustable heterointerface to prominently improve the activity and stability of Ru-based catalysts.

The exploration of advanced photocatalysts for efficient N₂ reduction reaction (NRR) by integrating facet-engineering and realistic N₂ active sites is very promising, but it remains a challenge due to the absence of rational structural design and atomic-level insights into molecular N₂ activation. Herein, the same main group transition metal (e.g., Co, Rh, and Ir) clusters were ingeniously modified onto the dominant {111} crystal facet of Cu₂O nanocrystal, aiming to track the synergistic effect of various N₂ active sites and facet-engineering for efficient N₂ photofixation. Intriguingly, further theoretical studies reveal that the incorporating Ir clusters can improve light absorption ability, accelerate photogenerated charge separation and transfer, and lower the reaction energy barrier, thereby expressively promoting the real photoreactivity. The present work offers a promising approach to cooperatively regulate the facet-engineering and N₂ active centers at the atomic level, expecting to guide innovative design of smart NRR systems.

Layer-by-layer (LbL) all-polymer solar cells (APSCs) are constructed with or without the incorporation of a Pt complex F-Pt as an energy donor additive in the acceptor layer. The power conversion efficiency (PCE) of LbL APSCs can be enhanced from 15.86% to 17.14% through introducing 0.2 wt % F-Pt in the PY-IT layer, originating from the efficient energy transfer from F-Pt to PM6 and PY-IT. The efficient energy transfer from F-Pt to PM6 and PY-IT can be well confirmed from the spectral overlapping between photoluminescence (PL) spectra of F-Pt and absorption spectra of PM6 and PY-IT, as well as the prolonged PL lifetime of PM6 and PY-IT according to the transient time-resolved PL spectra of blend and LbL films. The universality of the F-Pt incorporation strategy can be further confirmed from PBQx-TCl/PY-DT based LbL APSCs, and PCE can be increased from 17.57% to 18.29% by incorporating F-Pt into the PY-DT layer.

Atomically precise nanoclusters (NCs), which bridge the gap between molecular chemistry and nanochemistry, are drawing significant attention in various fields. Due to their discrete energy structures like molecules, NCs exhibit intriguing optical properties and defined metal sites, making them an ideal platform for studying photocatalytic reactions. This perspective elaborates the design principles for efficient NCs based water splitting photocatalysts from three fundamental aspects in photocatalysis: (1) light absorption and charge excitation, (2) charge separation and transport, and (3) surface reactions. An outlook on future work for developing NCs based water splitting photocatalysts is also provided.