ACS Materials Letters最新文献

Quantum technologies using electron spins have the advantage of employing chemical qubit media with tunable properties. The principal objective of material engineers is to enhance photoexcited spin yields and quantum spin relaxation. In this study, we demonstrate a facile synthetic approach to control spin properties in charge-transfer cocrystals consisting of 1,2,4,5-tetracyanobenzene (TCNB) and acetylated anthracene. We find that the extent and position of acetylation control the degree of charge-transfer and the optical band gap by modifying crystal packing and electronic structure. We further reveal that while the spin polarization of the triplet state is slightly reduced compared to prototypical Anthracene:TCNB, the phase memory (T_m) and, for 9-acetylanthracene:TCNB spin–lattice relaxation (T₁) time, could be enhanced up to 2.4 times. Our findings are discussed in the context of quantum microwave amplifiers, known as masers, and show that acetylation could be a powerful tool for improving organic materials for quantum sensing applications.

Photoassisted capture of uranium provides a promising strategy for the sustainable utilization of nuclear energy. Herein, we constructed Cu₂O/CuO heterojunctions in situ by a wet-etching method, showing ultrafast reaction kinetics and photocatalytic activity for U(VI) reduction. In 8 ppm of uranium-containing wastewater, the Cu₂O/CuO heterojunctions exhibited a remarkable uranium extraction efficiency of 94.6% within 10 min under irradiation, which exceeded most recently reported photocatalysts. The photocatalytic reaction rate constant of Cu₂O/CuO heterojunctions was 5.8-time larger than that of pure Cu₂O. A mechanism study indicated that the photogenerated electrons reduced CuO species in Cu₂O/CuO heterojunctions and in situ created the oxygen vacancy during the photocatalysis process, which strengthened the binding of UO₂²⁺. The rapid electron transfer rate over the in situ heterojunction interfaces and the enhanced UO₂²⁺ binding strength by the in situ formed oxygen vacancy accounted for the ultrafast reaction kinetics.

This work investigates carbon/tin composites as anode materials for high-performance sodium-ion batteries (SIBs). The material is prepared by dispersing SnO₂ nanopowder in fructose solution, followed by thermal treatment under inert gas, leading to fructose carbonization and carbothermal reduction of SnO₂ forming metallic Sn, confirmed by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Different thermal procedures, including a single-step with extended holding times and a two-step process, are explored; the latter separates fructose carbonization from carbothermal reduction, with the second step conducted under conventional heating conditions or via an ultrafast heating method. The composite with low carbon content exhibits a sodiation capacity of 749.2 mAh g^–1 in the first cycle with a high initial cycle efficiency (ICE) of 83.2%. After 100 cycles at 37.2 mA g^–1, it retains a capacity of 351 mAh g^–1. The material demonstrates excellent rate capability, maintaining a capacity of 344.5 mAh g^–1 at a rate of 2380 mA g^–1.

Additive engineering plays a vital role in enhancing perovskite solar cells (PSCs) by passivating defects within the perovskite films. Carboxyl and ester groups are commonly used for their strong binding with under-coordinated Pb²⁺ ions. However, the impact of additive acidity on the long-term stability of PSCs remains unclear. This study investigates the functional roles of 4-amino-3,5-difluorobenzoic acid (DFAB-A) and methyl 4-amino-3,5-difluorobenzoate (DFAB-AM), which could effectively passivate the film defects. However, the acidity resulting from carboxyl deprotonation in DFAB-A negatively impacts the structural stability of the perovskites. In contrast, DFAB-AM with its ester functionality forms stronger and more stable bonds, contributing to improved passivation and stability. PSCs incorporating DFAB-AM achieve a high power conversion efficiency of 22.51% and maintain 84.3% of their initial efficiency after 800 h of maximum-power-point operation. These findings underscore the importance of carbonyl group design in developing molecular additives to enhance both the efficiency and the durability of PSCs.

Dual-energy X-ray imaging technology provides more detailed material-specific information by using a second X-ray spectrum. However, conventional dual-energy X-ray imaging typically necessitates two separate exposures to combine high- and low-energy projections. This process can result in image misalignment and increased radiation doses. Herein, a dual-energy X-ray imaging system using a two-layered scintillator was developed, featuring transparent pure organic thermally activated delayed fluorescence (TADF) materials as the low-energy absorption layer and LYSO as the high-energy absorption layer. Separating the energy bins on the detector side enables the simultaneous and sequential acquisition of low- and high-energy projections with a single X-ray exposure. This two-layered scintillator achieves a high imaging resolution of 23 lp/mm, surpassing most conventional single-layer scintillators. Additionally, the effectiveness of this dual-energy imaging system was demonstrated in a toolbox inspection, where complex objects inside were successfully imaged and differentiated, capturing all intricate details in a single X-ray exposure.

The scarcity of strategies to finely modulate the interface assembly between MXene and semiconductors often restricts their full potential for photocatalysis. Herein, resorting to the cetyltrimethylammonium bromide (CTAB) surfactant intercalation effect, we report the rational synthesis of hierarchical seaurchin-like CdS-Ti₃C₂T_x MXene-CTAB (CdS-T-C) ensembles to modulate the interface and structure of MXene-semiconductor heterojunctions for significantly boosted photoredox coupling catalysis. The ternary CdS-T-C exhibits markedly enhanced activity toward visible light photoreforming of benzyl alcohol (BA) to benzaldehyde (BAD) and H₂ cooperatively, as compared to bare CdS and conventional CdS-Ti₃C₂T_x MXene (CdS-T) that suffer from serious MXene restacking with obvious electronic and optical property attenuation. Mechanistic studies reveal that the CTAB interfacial intercalation alleviates the restacking of Ti₃C₂T_x, thus weakening the light shielding effect while promoting the charge transport and surface activity of MXene. This work demonstrates an appealing strategy to regulate the interfacial cross-coupling configuration of MXene-semiconductor composites for efficient solar-to-chemical conversion.

Given the increasingly severe global climate change and energy crisis, the conversion of carbon dioxide (CO₂) into very valuable chemicals has been proposed as an attractive solution. The electrocatalytic CO₂ reduction reaction (eCO₂RR) represents a remarkably efficient pathway for reducing CO₂ under mild conditions. Metal cluster-based crystalline materials (MCMs) have garnered significant interest in the area of CO₂RR because of their elevated concentration of active sites, tunable backbone structures, and excellent stability. These materials enable precise control of metal valence states and charge transfer pathways, offering a variety of reduction pathways for CO₂RR. Herein, we examine the utilization of MCMs in eCO₂RR in recent years. We cover the fundamental principles of electrocatalytic CO₂ reduction, the synthesis approaches for these materials, and the connection between structural characteristics and catalytic performance. Additionally, the paper delves into the challenges and opportunities presented by MCMs for enhancing CO₂RR efficiency and selectivity. Herein, we aim to provide researchers with a new perspective on MCMs in the field of eCO₂RR, thereby improving understanding of the relationship between structure and performance. Ultimately, this work seeks to advance the technology for eCO₂RR, contributing significantly to sustainable energy production and the mitigation of greenhouse gas emissions.

The nondegradability, nonreusability, and flammability of epoxy coatings have brought serious environmental and safety issues. Herein, a multifunctional, fire-retardant epoxy vitrimer coating (DCNC/45PETO) was prepared via curing bis(2,3-epoxypropyl)cyclohex-4-ene-1,2-dicarboxylate (DCNC) with a well-designed phosphaphenanthrene-containing polyethylenimine (PETO) at room temperature. DCNC/45PETO exhibits excellent adhesion to different substrates, with a high adhesive strength of 7.9 MPa on wood, outperforming previous wood coatings/adhesives. The DCNC/45PETO coating endows wood with excellent fire retardancy, including a high limiting oxygen index of 34.0% and a vertical burning (UL-94) V-0 rating. DCNC/45PETO demonstrates durable adhesion and fire-retardant performances in harsh environments. The self-catalytic transesterification within the DCNC/45PETO network effectively avoids the application of extra toxic catalysts, and this coating can be reused for at least 5 times in mild conditions without compromising its performances. This study provides an innovative design strategy for creating multifunctional vitrimer coatings, showing great application potential in the construction field.

Developing multifunctional adsorbents with exceptional capture performance and outstanding antibiofouling activity is of great significance for the recovery of gold. However, most of the reported materials only have a single adsorption function, which restricts their practical application for gold extraction from complex matrices. Herein, we construct a series of three-component covalent organic frameworks (COFs) with good antibacterial performance for the extraction of gold. All the obtained COFs show high adsorption capacities over 1250 mg·g^–1 for gold, which may be attributed to the high specific surface area, regular pore structure and abundant binding sites. In particular, the optimized materials COF-TPTD-DHTA-TAB gives excellent adsorption capacity (2884 mg·g^–1), ultrafast adsorption kinetics (60 min) and high distribution coefficient (K_d > 4 × 10⁵ mL·g^–1). More importantly, good sterilization performance is observed on both COF-TPTD-DHTA and COF-TPTD-DHTA-TAB under visible light irradiation. This work provides a paradigm to develop ionic three-component COFs with antibacterial activity for gold recovery.

Developing skin-like ionic sensing materials is highly desirable for skin bioelectronics for long-term health monitoring, which is challenging to realize by using biocompatible natural polymer-based biogels. Herein, we engineer a robust natural protein-based ionic biogel with skin-like combinational properties involving stretchability, softness, durability, ionic conductivity, and environmental adaptability, which is enabled by a synergistic effect of biomimetic nanofibrous structures as well as solvent and ionic enhancement. The skin-like mechanics and functionality of the as-designed natural protein-based biogels suggest their further applications in advanced skin sensors for long-term and high-fidelity physiological monitoring. As a proof of concept, we successfully demonstrate high-quality continuous monitoring of electrocardiograms for 1 week under daily life conditions using such natural protein-based skin-like ionic biogels.