ACS Materials Letters最新文献

Photoresponsive metallopolymers have attracted increasing interest owing to their potential applications in enabling circular recycling and self-healing material systems. The high spatiotemporal precision of light irradiation allows for the selective cleavage and reformation of dynamic reversible bonds. This capability facilitates precise manipulation of topological structures at the molecular level and enables on-demand modulation of bulk material morphology and properties at the macroscopic scale, thereby supporting diverse functional applications. Herein, we present a series of sustainable materials based on photoresponsive metallopolymers that operate via distinct mechanisms, including ligand photosubstitution, photothermal effects, photoinduced redox reactions, and metal–ligand coordination controlled by nonmetallic photoresponsive groups.

We report polymer electrolytes for high areal capacity rechargeable Ag–Zn alkaline batteries. Using initiated chemical vapor deposition (iCVD), we deposit submicrometer-thick copolymers of divinylbenzene (DVB) and 4-dimethylaminomethylstyrene (DMAMS) on two-dimensional and three-dimensional substrates. We convert the as-deposited copolymer p[DVB-DMAMS] into an anion-conducting electrolyte by quaternizing the tertiary amines in DMAMS followed by ion exchange with OH^– to form p[DVB-DMAMS⁺(OH^–)]. The highest performing water-swelled polymer electrolyte supports Ag–Zn redox without dissolved salts and exhibits single-ion OH^– conductivity approaching 1 × 10^–4 S cm^–1. We demonstrate a solid-state battery comprising opposing Ag and Zn sponge electrodes coated with submicrometer-thick p[DVB-DMAMS⁺(OH^–)] with an additional 300 μm-thick freestanding layer of the same copolymer between the electrodes serving as a macroscale separator and electrolyte. These cells deliver average areal capacities exceeding 7.9 mAh cm^–2 (one of the highest reported for Ag–Zn) with Coulombic efficiency reaching 98%.

Soft-solid molecular crystals consist of crystalline grains and fluid grain boundaries (GBs) that enhance the grain binding and transport of Li⁺ ions between the grains. The total ionic conductivity consists of ion migration in both the grains and GBs. To unravel these contributions in adiponitrile (Adpn):LiPF₆ molecular crystals, the GB volume fraction was varied by changing the size of the crystals and the Adpn:LiPF₆ molar ratio. Molecular dynamics (MD) simulations indicate that ion motion was subdiffusive in the grains and “well-diffusive” in the GBs, with GBs characterized as disordered nanoconfined regions of higher charge carrier concentration (∼1 M) than in saturated Adpn:LiPF₆ solutions (0.04 M), and Li⁺ ions predominantly solvated by cyano groups with few contact ion pairs. The diffusivity in the GBs is at least an order of magnitude higher than that in the crystalline grains. The emergent picture is the grains as a reservoir of ions that migrate to faster-conducting GBs.

Nylon-based fiber-reinforced composites are widely used in various sectors due to their strength, durability, and lightweight properties. Despite their widespread use, recycling these composites is difficult due to the inability to separate fibers and thermal instability of nylon at high temperatures. Consequently, most nylon composites are landfilled, leading to significant economic loss. Current fiber recovery methods (i.e., pyrolysis) are energetically inefficient and preclude recovery of the matrix. Dissolution methods, such as using hexafluoroisopropanol (HFIP), allow recovery of polymer and fiber but are economically taxing and require extensive safety infrastructure. Herein we report tailored glycolysis of nylon-6 composites, resulting in separated constituent fibers and nylon-6 oligomers. Deconstruction kinetics reveal nylon’s molecular weight reductions from 32,600 to 2000 g/mol, while SEM and tensile testing confirm recovered fiber integrity. This approach offers a pathway to reclaim high-value materials from nylon composites, providing a strategy for the chemical recycling of fiber-reinforced composites.

Superhydrophobic surfaces with excellent anti-icing performance show promising applications in many low-temperature systems. Understanding the nucleation characteristics of subcooled droplets is of importance for designing advanced anti-icing/frosting surfaces. Here, we demonstrate that the ice crystallization mode of subcooled droplets is dependent on both the wetting state and airflow conditions, along with interfacial heat transfer analysis for determining the nucleation position. Based on the nucleation theory and heat transfer model of the gas–liquid–solid interfaces, a dimensionless parameter β to evaluate the tendency of homogeneous nucleation is proposed to predict the ice crystallization mode in complex environments, which is validated over a wide range of surface properties and airflow conditions. The critical airflow velocity required to trigger homogeneous nucleation decreases with the increase in the water contact angle. This work deepens the understanding of the nucleation dynamics and interfacial heat transfer, providing insights for designing high-performance anti-icing/frosting surfaces.

Developing sustainable strategies for ambient ammonia synthesis is a critical challenge in materials science and catalysis. While bioinorganic hybrid systems have emerged as a promising solution by combining the light-harvesting efficiency of semiconductors with the catalytic specificity of biological nitrogenases, balancing material toxicity with electron transfer efficiency remains a major bottleneck. In this study, we constructed a robust and biocompatible inorganic-bacterial hybrid system via the in situ binding of magnetite (Fe₃O₄) nanoparticles (NPs) to whole-cell microorganisms. In this architecture, Fe₃O₄ NPs function as photosensitizers that capture solar energy to generate photoexcited electrons. These electrons are efficiently transferred to the attached Azotobacter vinelandii (A. vinelandii), thereby supplementing the intracellular electron pool. This continuous exogenous electron supply significantly boosts the energy conversion efficiency and nitrogenase activity within the biohybrid. This study underscores the potential of nanobiohybrid systems in solar-to-chemical energy conversion and paves the way for the sustainable production of diverse functional chemicals utilizing solar energy.

Nanohoops are a class of fascinating curved materials that have started to show their potential in organic electronics. Now, the next step consists of going deeper in their rational design in order to reach high performance materials. However, at this stage of their evolution in material science, the nanohoop properties and their device performance are far more complicated to forecast than those of their linear counterparts, and systematic studies dealing with the incorporation of functional units have to be carried out. Herein, we report a [4]cyclo-2,7-carbazole, possessing an electron-rich thiophene unit grafted on its nitrogen atoms. Incorporation in Organic Field-Effect Transistors (OFET) provides a saturated mobility of 3.2 × 10^–5 cm² V^–1 s^–1, among the highest reported to date for nanohoops. The other characteristics such as the low subthreshold swing (0.72 V/dec) or the high on/off values of the drain-source current (2.8 × 10⁵) appear even to be the highest reported to date for a nanohoop.

The climate crisis demands clean energy technologies to cut CO₂ emissions from fossil fuels. Hydrogen fuel cells and solar-driven CO₂ reduction are promising, but both rely on efficient water oxidation. Polypyridyl ruthenium complexes are active catalysts for water oxidation; however, they exhibit poor stability and recyclability. Our group improved performance by embedding these complexes into metal–organic frameworks (MOFs). As water oxidation is pH-dependent, proton management further enhances reactivity. To address the issue, we introduced proton transfer pathways into the MOF structure. Specifically, we incorporated −SO₃H groups onto the biphenyl linkers of UiO-67 loaded with [Ru(tpy)(dcbpy)OH₂]PF₆ catalyst (where tpy = 2,2′:6′,2″-terpyridine; dcbpy = 5,5-dicarboxy-2,2′-bipyridine). The sulfonated MOF exhibited a 2.5-fold increase in oxygen evolution compared to the nonsulfonated analogue. After 1 h of electrolysis, the sulfonated MOF exhibited a turnover number of 25 for oxygen evolution reaction compared to 10 for the native MOF, demonstrating the benefits of built-in proton management.

The incorporation of multiple functional groups or metal sites into predetermined positions of a metal–organic framework (MOF) cavity would obtain tailored MOF materials, which greatly facilitate their modulated light harvesting, band gap, and consequently photocatalytic activity. Herein, a multicomponent zirconium MOF, JLU-MOF58(Ni)-PDI, was achieved by incorporating PDI (short for perylene diimide) and Ni²⁺ sites into JLU-MOF58. JLU-MOF58(Ni)-PDI exhibited visible-light-driven reduction of CO₂ in the absence of any additives under mild conditions. In addition, the CO production rate of JLU-MOF58(Ni)-PDI was 3.2 to 12.8 times higher than a series of classical materials, which can be assigned to the efficient introduction of the photosensitive fragments and catalytically active sites into the parent MOF. Furthermore, the catalytic mechanism was studied in detail by a series of experiments and density functional theory calculations.

Size quantization in halide perovskite nanocrystals provides a versatile strategy to tune their optical and electronic properties. We have now synthesized CsPbI₃ quantum dots (QDs, 5–13.5 nm) by first preparing CsPbBr₃ QDs at room temperature, followed by postsynthetic halide exchange with iodide ions. As the QD size decreases from 13.5 to 5 nm, we observe a pronounced blue shift in both excitonic and emission peaks, accompanied by an increase in the Stokes shift. The reduction in the excited-state lifetime with decreasing QD size is attributed to enhanced intrinsic exciton recombination and a higher density of surface defects. Photoinduced electron transfer between quantized CsPbI₃ and methyl viologen revealed an ultrafast process occurring within a few picoseconds. These size-dependent excited-state dynamics and charge-transfer properties highlight the potential of CsPbI₃ QDs for photocatalytic solar fuel generation and optoelectronic applications.