ACS Materials Letters最新文献

Engineered living materials (ELMs) harness the adaptive capabilities of biological systems to create diverse functional materials. While most ELM strategies rely on static microbial assemblies, the role of bacterial motility in structuring living materials remains largely unexplored. Here, we demonstrate that swarming motility in Escherichia coli MG1655 can spatiotemporally organize calcium phosphate. Scanning electron microscopy and X-ray diffraction patterns differentiate regularly spaced concentric hydroxyapatite deposition of bacteria from abiotic precipitation. We further show that bacterial activity promotes local alkalinization, contributing to calcium phosphate mineralization, and that phosphate chemistry, along with calcium concentration, modulates both swarming and mineral patterning. A continuum model captures the spatiotemporal coupling between swarm expansion and mineral deposition, showing that recurrent front arrest and restart can generate concentric rings. Together, we establish bacterial swarming as a dynamic mechanism for spatially organizing biomineralization and provide a framework for programmable pattern formation in ELMs.

Atomically dispersed metal−nitrogen−carbon (M−N−C) catalysts have emerged as promising alternatives to platinum-based catalysts for the oxygen reduction reaction (ORR). However, comprehensive and systematic reviews focusing on activity-enhancement engineering and stability-improvement strategies remain scarce, leading to an ambiguous understanding of the structure-activity-stability relationship. Therefore, this review systematically summarizes heteroatom doping engineering, and stability enhancement strategies, aiming to offering new insights to break the activity-stability trade-off. Firstly, the regulation mechanisms of heteroatom doping strategies on the electronic structure of active centers and ORR performance are discussed in depth. Specifically, this review encompasses the electronic modulation of the central metal via first coordination shell engineering, the structural optimization of the carbon support through second-shell doping, and the synergistic catalytic effects derived from multiheteroatom codoping. Then, the deactivation mechanisms of M–N–C catalysts are summarized, along with corresponding strategies for stability enhancement. Finally, future research directions for atomically dispersed M–N–C catalysts are proposed.

X-ray dosimetry and imaging have been utilized in a wide range of applications. However, the complex components of detection, memory, and computing units of commercial detection systems inevitably make it structurally complex and energy consuming. Here, a multimodal two-terminal perovskite device is demonstrated that can measure real-time dose rate and record the accumulated dose of X-ray pulse signals concurrently by decoupling volatile electronic and non-volatile ionic variables of the conductance (G). The device delivers an X-ray sensitivity of 1159 μC Gy^–1 cm^–2, a limit of detection (LoD) of 27.9 nGy s^–1, a limit of memory (LoM) of 0.32 μGy s^–1, as well as multiple non-volatile storage states of around 40 nS. As a proof-of-concept, a perovskite crossbar array integrates the functions of sensitive X-ray detection, multi-state data memorization, as well as image pre-processing, offering a promising platform toward intelligent, robust, and lightweight radiation imaging systems.

Two-dimensional conductive metal–organic frameworks (2D c-MOFs), such as Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂ (Ni₃(HITP)₂), are promising active materials for electrochemical energy storage due to their intrinsic conductivity and well-defined porous structures. However, their predominantly microporous nature limits ionic transport, leading to poor performance at fast charging rates. Herein, we report a soft-template strategy using a symmetric triblock copolymer to introduce mesoporosity into Ni₃(HITP)₂. The resulting materials exhibit preserved crystallinity and hierarchical pore structures, with mesopores of 3–5 nm confirmed by both nitrogen sorption and transmission electron microscopy. This work demonstrates the creation of mesopores in 2D c-MOFs via a soft-template approach. The mesopores of Ni₃(HITP)₂ facilitate the mass transfer of ions and thus enhance the rate capability for the application in supercapacitors, highlighting soft-template engineering as an effective strategy for tuning pore structure and electrochemical performance.

Reaction−diffusion waves provide a mode of spatiotemporal signal propagation in excitable media, yet passive control of their transport is typically limited to slowing or blocking. Here, using the Belousov−Zhabotinsky (BZ) reaction as a model-excitable system, we show that fixed ionic charge in polyelectrolyte hydrogels provides a sign-reversible, composition-tunable handle for wave transport. Anionic gels retard BZ waves by up to 35%, whereas cationic gels accelerate them by up to 23% above the incoming bulk reference; chemically distinct monomers reproduce the same sign-dependent trend. Reduced Oregonator modeling shows that diffusion-only control cannot account for the full response and is consistent with a shift in effective local excitability, without assigning a unique microscopic mechanism. A triangular anionic gel further converts local retardation into refraction-like steering. These results establish fixed-charge chemistry as a passive materials parameter for tuning BZ-wave speed and trajectory, providing a foundation for chemically encoded signal-routing materials.

The electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising route to biobased polymers using Ni-based hydroxide anodes. Although Co incorporation enhances performance, its mechanistic role in HMF oxidation remains unresolved. Here, NiCo hydroxides with precisely controlled Co contents were synthesized and evaluated. Trace Co incorporation (Ni₉₉Co₁) markedly enhanced FDCA production, achieving a production rate of up to 1.27 mM cm⁻² h⁻¹, a 48% increase over pristine Ni (0.86 mM cm⁻² h⁻¹), while maintaining the highest Faradaic efficiency (91%). Higher Co loadings instead favored the competing oxygen evolution reaction (OER), reflecting a mechanistic trade-off. Operando spectroscopies and theoretical calculations reveal that Co acts not as a catalytic site but as an electronic promoter: it lowers the Ni²⁺/Ni³⁺ transition barrier, stabilizes active NiOOH, and facilitates FDCA desorption. Excessive Co destabilizes NiOOH and accelerates OER. These findings establish dopant-level Co as a redox-modulating promoter for selective biomass electro-oxidation.

Utilizing the inherent properties of copper could realize tumor therapy through ferroptosis and cuproptosis pathways. However, the therapeutic efficiency is always compromised by the intracellular antioxidant ability and cytoprotective autophagy process. Herein, enhanced tumor ferroptosis/cuproptosis was realized using copper phosphate-sorafenib-polyacrylic acid (CuPi-SRF-PAA) nanoparticles (NPs). They could degrade to release Cu²⁺, SRF, and PO₄^3– under acidic conditions. The released Cu²⁺ not only promotes lipid hydroperoxides generation through a Fenton-like reaction to cause ferroptosis but also damages mitochondrial dihydrolipoamide S-acetyltransferase to induce cuproptosis. Meanwhile, SRF inhibits glutathione generation through deactivating system xc^– to realize redox balance disruption, and PO₄^3– causes lysosomal deacidification to achieve autophagy blockage, enhancing the efficacy of ferroptosis and cuproptosis. In vitro and in vivo data demonstrated that these CuPi-SRF-PAA NPs could achieve effective tumor suppression with high biocompatibility. This work highlights the key roles of combining redox balance disruption and autophagy blockage in tumor therapy.

The emerging solid-state battery technology must be enabled at sub-zero temperatures. This study investigates the effect of high-energy ball milling on sodium decahydrido-closo-1-carbadecaborate (NaCB₉H₁₀) by mechanically treating the solid electrolyte for 0, 15, 45, and 90 min. We show that mechanical treatment of NaCB₉H₁₀ stabilizes the highly sodium ionic conducting disordered ht-NaCB₉H₁₀ polymorph at temperatures down to –40 °C. Stable sodium stripping and plating in symmetrical Na|SE|Na cells is displayed at –10 °C for the solid electrolytes that were milled for 15 and 45 min. Furthermore, a novel polymorph of NaCB₉H₁₀ is revealed at low temperatures and tentatively ascribed to a monoclinic unit cell with space group P2₁/c. This work marks an important step toward tailoring closo-borate solid electrolytes for usage in low-temperature solid-state batteries.

Lithium cobalt oxide (LCO), a layered lithium-ion battery cathode material, undergoes pronounced chemical and structural reprogramming at the plant interface. Here we show that root-associated conditions convert LCO nanosheets into a high-aspect-ratio needle-like state while preserving the layered oxide framework, consistent with interfacial reconstruction rather than bulk collapse. The transformed material becomes oxidizing under rhizosphere-relevant mild acidity and produces singlet oxygen as the dominant reactive species. Kinetic analysis, pharmacological perturbation, and genetic evidence further show that this early material-derived oxidative input is followed by apoplastic RBOH-dependent ROS production in the plant. These results define a coupled injury mechanism in which rhizosphere-driven transformation creates the initial oxidizing state and the plant amplifies it through its own ROS machinery. LCO phytotoxicity therefore arises from interfacial chemical evolution, rather than from pristine material identity or ion release alone.

Mo-activated halide perovskites are emerging as a distinctive class of transition-metal-activated luminescent materials. Octahedral Mo³⁺ centers give sharp near-infrared spin-flip and upconversion photoluminescence (PL), whereas emissive centers associated with higher-valence Mo can produce broadband near-infrared PL. These properties are attractive for photophysics and optoelectronics but depend sensitively on the Mo oxidation state, first-shell coordination, ligand-field strength, and oxygen incorporation. This review critically assesses recent progress in Mo-activated halide perovskites. We summarize the electronic structure and selection rules of Mo³⁺ and analyze Mo³⁺-centered downconversion and upconversion PL. We then examine broadband PL from halide and oxyhalide perovskites containing higher-valence Mo, highlighting both the evidence for Mo-related emission and the remaining ambiguity in emissive-center assignment. We finally discuss future directions for target-specific host selection, controlled enhancement of Mo³⁺ radiative transitions and sensitized excitation, quantitative performance evaluation, and predictive materials design, with the aim of moving Mo-activated halide perovskites from spectroscopic observations toward rationally designed luminescent materials.