ACS Materials Letters最新文献

Low photoluminescence quantum yield (PLQY) has long been one of the key issues that impedes the versatile applications of gold nanoclusters (AuNCs). In this work, melamine–formaldehyde polymer nanoparticles were employed as carriers to encapsulate AuNCs (AuNCs-MF PNPs), which can trigger the confinement induced enhanced emission (CIEE) effect, remarkably enhancing the PLQY more than 25 times from 1.46% (AuNCs) to 36.90% (AuNCs-MF PNPs) and improving the stability toward pH. By simultaneously incorporating AuNCs-MF PNPs and CDs as sensing probes, ratiometric fluorescence detection of H₂S with improved sensitivity was achieved. To realize the on-site detection of H₂S, a portable sensing platform based on a smartphone was constructed. Considering the high PLQY of AuNCs-MF PNPs, a light-emitting device (LED) was fabricated based on AuNCs-MF PNPs with favorable characteristics. This work not only provides a novel strategy for preparing AuNCs with high PLQY but also highlights their potential in fluorescence sensing and the field of intelligent luminescence.

Solar-driven CO₂ reduction combined with plastic waste valorization presents a versatile approach to simultaneously reset misaligned hydrocarbon resources and achieve a carbon-neutral cycle. Herein, we demonstrate a co-upcycling heterogeneous photoredox catalysis for efficient CO₂ reduction to tunable syngas, integrated with polyethylene terephthalate (PET) plastic conversion for accessing acetate, over the spherical band-gap-engineered Zn_xCd_1–xS catalyst. The key to steering the syngas H₂/CO rate is to modulate the conduction band bottom potentials of the Zn_xCd_1–xS photocatalysts by altering the Zn/Cd ratio, which results in syngas H₂/CO production over a wide range. Moreover, controlled variations in the molar ratio of Zn/Cd regulate the electron–hole separation capability, thereby endowing Zn_0.8Cd_0.2S with the optimum syngas and acetate production rates. The underlying mechanistic origin of such a redox reaction involving CO₂-assisted PET plastic conversion has been systematically investigated. This win-win cooperative photoredox catalysis offers a tantalizing possibility for co-upcycling of CO₂ and PET into value-added feedstocks.

Whenever the cycling of Li-ion batteries is stopped, the electrode materials undergo a relaxation process, but the structural changes that occur during relaxation are not well-understood. We have used operando synchrotron X-ray diffraction with a time resolution of 1.24 s to observe the structural changes that occur when the lithiation of graphite and LiFePO₄ electrodes are interrupted. Assessing the kinetics of the relaxation processes coupled with molecular dynamics simulations allows us to identify three relaxation stages in graphite. The atomistic origin for the relaxation process within the partially lithiated graphite structure is driven by the reorganization of Li ions into Li clusters. Relaxation in LiFePO₄ electrodes is considerably slower than for graphite, but the observed structural changes is also attributed to reorganization of Li ions. These insights highlight the nature of the structural changes that occur during relaxation and the importance of using operando structural studies to avoid misleading conclusions about the reaction mechanisms in battery materials.

Perovskite solar cells have attracted extensive attention due to their simple manufacturing process and high efficiency. However, defects between the perovskite and hole transport layer can lead to nonradiative recombination of photogenerated carriers and severe ion migration, which accelerates the degradation of such devices. Here, we chose to deposit an Al₂O₃ porous insulating layer on the surface of the perovskite film. At the same time, we chose to introduce NMABr (1-Naphthylmethylamine Bromide) into Al₂O₃ as a modifier to overcome the issue that applying Al₂O₃ alone may hinder interfacial carrier transport due to the uncontrolled morphology. The addition of NMABr not only has a passivation effect but also changes the morphology of the Al₂O₃ layer. Under the synergistic effect of Al₂O₃ and NMABr, a porous insulating contact layer is better formed, which is conducive to carrier transport and improves the stability and efficiency.

Whenever the cycling of Li-ion batteries is stopped, the electrode materials undergo a relaxation process, but the structural changes that occur during relaxation are not well-understood. We have used operando synchrotron X-ray diffraction with a time resolution of 1.24 s to observe the structural changes that occur when the lithiation of graphite and LiFePO₄ electrodes are interrupted. Assessing the kinetics of the relaxation processes coupled with molecular dynamics simulations allows us to identify three relaxation stages in graphite. The atomistic origin for the relaxation process within the partially lithiated graphite structure is driven by the reorganization of Li ions into Li clusters. Relaxation in LiFePO₄ electrodes is considerably slower than for graphite, but the observed structural changes is also attributed to reorganization of Li ions. These insights highlight the nature of the structural changes that occur during relaxation and the importance of using operando structural studies to avoid misleading conclusions about the reaction mechanisms in battery materials.

Cu-based materials are regarded as effective electrocatalysts for CO₂RR; however, Cu⁺, the active site for C–C coupling, is unstable under reduction conditions. Herein, Mg²⁺ is doped into the Cu₂O/CuO interface and generates high-activity Cu⁺–O-Mg²⁺ sites following electrochemical activation. The electron-withdrawing effect of Mg²⁺ in the Cu⁺–O-Mg²⁺ site stabilizes Cu⁺ and optimizes the reaction pathway for CO₂RR. At a partial current density of 567.21 ± 5.18 mA cm^–2, the Faraday efficiency (FE) for C₂₊ products can reach 81.03 ± 0.74%. In situ Raman and in situ infrared spectroscopy reveal that the Cu⁺–O-Mg²⁺ site significantly enhances the coverage and stability of *CO, which contributes to the ultrahigh selectivity of CO₂ toward C₂₊ products. Density functional theory (DFT) studies indicate that *CO₂ is readily adsorbed on the Cu⁺–O-Mg²⁺ site, facilitating the more effective generation of *CO, which subsequently promotes the electrochemical C–C coupling step and accelerates the production of C₂₊ products.

Thermodynamic metastable nanomaterials display attractive properties due to their unique atom configuration and microstructure, distinct from their counterparts found in equilibrium phase diagrams. However, their fabrication remains a grand challenge because conventional methods are generally operated under near-equilibrium conditions. To break the thermodynamic limits for discovering novel materials, numerous fabrication methods by adopting extreme strategies have been developed, including ultrafast synthesis, Joule heating, carbon thermal shock, pulse heating, extreme temperature gradients, and rapid solidification. A common feature of these methods is that the target material is processed under a far-from-equilibrium (FFE) thermodynamic state, where a new kinetic route is created for the evolution of an unprecedented composition/structure. In this review, we provide a unifying view and guiding strategies for engineering FFE environments during materials synthesis, categorized within both temporal and spatial dimensions of the thermodynamic landscape. Furthermore, we highlight the potential of FFE materials, not only as platforms for deeper understanding nonequilibrium behaviors, but also as a framework for designing innovative materials for advanced technologies.

The supermolecular building block approach is powerful in constructing hierarchically porous metal–organic frameworks (MOFs). However, the structural diversity of these extended frameworks built from the same building blocks has never been explored. Herein, we propose a strategy by synergistically tuning the extending direction of metal–organic polyhedra (MOPs) and the linker conformation to achieve MOFs with framework isomerism. Six novel MOFs (CCNUF-1–6) based on an octahedral MOP and different tritopic pyridine-based linkers were successfully synthesized, among which the structural diversity increased with increasing linker flexibility. The topologies (sql, kgd, and rtl) of these materials are unprecedented in MOP-based MOFs. Moreover, highly porous CCNUF-2–6 showed remarkable iodine uptake capacities in the range of 2.51 to 3.11 g g^–1. This study emphasizes the potential of MOPs containing open metal sites as versatile platforms for the development of diversified hierarchically porous MOFs with enhanced functional properties.

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 (T ₁) 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.

The exceptional structural plasticity and well-balanced properties of oxychalcogenides make them highly desirable as infrared nonlinear optical (IR NLO) materials. A breakthrough in the design of high-performance oxychalcogenides involves integrating and assembling multiple anionic units to maximize their functions. Following this approach, we developed La₃(Ga₃S₃O₃)(Si₂O₇) (LGSSO) by simultaneously incorporating [Ga₃O₃S₆] and [Si₂O₇] groups. The potential of LGSSO as an IR NLO material is evident from its wide bandgap (4.82 eV, runner-up in NLO oxychalcogenides), high laser-induced damage threshold (8.7 × AgGaS₂ at 1064 nm), attractive birefringence (0.122 at 546 nm), and moderate phase-matching second-harmonic generation response (1.7 × KH₂PO₄ at 1064 nm, 0.3 × AgGaS₂ at 1910 nm). Theoretical studies indicate that the [LaS₂O₆] and [GaO₂S₂] contribute significantly to the NLO coefficient, while the [Ga₃O₃S₆] trimers with pronounced polarizability anisotropy play a pivotal role in providing a substantial birefringence. This work offers a tangible paradigm for exploring well-performed oxychalcogenide NLO material.