ACS Materials Letters最新文献

As an emerging artificial synapse for emulating the human brain, the memristor is promising owing to its excellent ability to mimic synaptic functions. In this work, we report an analogue memristor based on a composite of hydrothermally oxidized Ti₃C₂T_x MXene and ligand-exchanged ZrO₂ quantum dots (QDs), synthesized via a solution-based method using DMF at a 1:2 weight ratio. The resulting Ag/oxidized MXene-ZrO₂ QDs/FTO (fluorine-doped tin oxide) memristor exhibits a transition from digital to analogue resistive switching (RS) due to the integration of the ZrO₂ QDs. It supports 18 linearly modulated conductance levels, enabling multilevel memory storage beyond 4 bits. Its reliable and reconfigurable switching behavior supports synaptic weight modulation and image recognition tasks in an artificial neural network. The synergistic interaction between oxidized MXene and ZrO₂ QDs in the composite enables low-power operational analogue memristors with tunable synaptic plasticity, making it suitable for next-generation neuromorphic computing devices.

Polycrystalline two-dimensional (2D) materials yield in-plane strain inhomogeneity due to the residual mismatch accumulated from stitching misoriented grains. Since optoelectronic properties of 2D materials are sensitive to the in-plane strain, characterizing and controlling this strain landscape is key to wafer-scale uniformity. Here, we introduce a polymer-assisted thermal relaxation process that reduces in-plane strain inhomogeneity in polycrystalline monolayer MoS₂ films. By heating the polymer substrate above its glass-transition temperature, the MoS₂ films on the polymer substrate spontaneously form three-dimensional wrinkles and relieve their strain inhomogeneity. A Raman spectroscopy-based metric is proposed to quantify the strain inhomogeneity in the films across various grain sizes. Finally, we demonstrate that incorporating thermal relaxation into a conventional dry-transfer process reduces strain inhomogeneity by up to 50% relative to as-grown films. This work provides a practical approach to characterize and mitigate strain inhomogeneity in polycrystalline TMDs, enabling homogeneous, wafer-scale 2D films.

Self-trapped exciton (STEs)-driven emission has made zero-dimensional (0D) halide perovskites unique and promising for light-emitting technologies. Strain engineering modulates STEs and shows a unique sharp modulation of emission properties at a particular range of external pressure in 0D all-inorganic perovskites. Using state-of-the-art first-principle calculations on A₄BX₆ perovskites, we have unveiled the structural origin of this observation. We find that, at a critical pressure range, STE get a sharp stabilization due to the [BX₆]^4– octahedral twisting and the concomitant emergence of strong halogen–halogen noncovalent interaction between the neighboring octahedra, resulting the formation of axially elongated and equatorially compressed [BX₆]^4– octahedra, making ns² lone-pair stereochemically active and facilitating higher extent of electron–hole overlap, resulting in the formation of highly stable well-defined STE. This study offers a comprehensive understanding of strain-induced optoelectronic modulation in 0D perovskites and unveils the origin of the experimental observations on emission enhancement at a critical range of pressure.

RNAs and DNAs with identical sequences often adopt distinct structures. To understand the connection between RNA and DNA structures of an identical sequence, we used the RNA square as an experimental model to study the structural transformation from RNAs to DNAs. Interestingly, we found that the RNA square can transform into a mixture of square and triangle by gradually replacing RNA with DNA nucleotides and finally transform into a DNA triangle by total DNA nucleotide replacement. The oxDNA simulation results reveal that the RNA–DNA hybrid square becomes destabilized, while a hybrid triangle emerges. Further, by reducing the loop length of the DNA motif, it could assemble into triangles, squares, or pentagons with sufficient flexibility, similar to the RNA ones. Our experimental results have demonstrated the different self-assembly pathways of RNA and DNA with the same sequence, which provides a homoassembly strategy for studying the structural transformation from RNAs to DNAs.

Electrochemically integrated carbon capture and utilization (eICCU) couples carbon capture with electrolysis to convert captured CO₂ directly into feedstocks, avoiding thermal regeneration, compression, and gas purification. This integration can raise carbon, energy, and system efficiencies, yet progress is limited by an incomplete mechanistic insight, the absence of absorbent selection rules, and a lack of catalyst design principles. This review clarifies these gaps and outlines a framework to accelerate the field. We (i) define eICCU and benchmark it against sequential capture-then-electrolysis routes; (ii) catalog milestones across absorbent classes─amines, hydroxides, and amino acid salts─and distill criteria for optimal selection and blend design; (iii) assess emerging catalyst families, highlighting speciation-aware optimization and priorities for multicarbon products; and (iv) discuss system architecture from absorber to electrolyzer and product separation. Addressing these elements positions eICCU to enable lower-energy carbon mitigation and on-site sustainable feedstock production within a circular carbon economy.

Salt hydrates are a promising thermochemical energy storage medium that stores heat through the reversible uptake (hydration) and release (dehydration) of water vapor. Our study deploys operando neutron imaging to investigate salt hydrate performance with high spatial resolution (42 μm pixels). For flow over a packed bed with diffusion-driven transport, measurements reveal the formation of a solid diffusion layer due to particle swelling for the pure SrBr₂ salt. In contrast, the SrBr₂–vermiculite composite exhibits significantly less swelling and more than a 2-fold increase in the apparent water vapor diffusivity. For axial flow through a packed bed, neutron imaging confirms theoretically predicted transitions from a moving reaction front to a homogeneous profile with an increase in humid air flow rate. Our study establishes neutron imaging as a powerful technique to advance fundamental understanding of thermochemical systems and help guide composite material design.

Programmability is essential for magnetic microrobots to achieve adaptive and multifunctional behaviors. However, most existing systems lack reconfigurability after deployment. Here, we present a reprogrammable microrobot platform based on nickel nanowires of distinct diameters embedded in SU-8, leveraging the difference in their coercivities to enable in situ magnetization switching. A fast, purely magnetic reprogramming strategy is developed, allowing the selective reversal of magnetization states without thermal or structural changes. We systematically explore the effects of ramp time, magnetic field strength, and microrobot geometry on reprogramming success and demonstrate six distinct deformation and locomotion modes in a multisegment robot. The scalable UV photolithography-based fabrication process ensures a high yield and design flexibility. This work provides a generalizable and efficient approach toward reprogrammable microrobotic systems with potential for future applications in dynamic environments such as biomedical actuation or soft robotic manipulation.

Anisotropy has been extensively harnessed in heat control, energy harvesting, and light–matter interaction (LMI) systems. As a renowned LMI compound, the LMI anisotropy of TiO₂ has so far remained elusive. Leveraging the highlight anisotropy characters in the 2D crystal, here, we revealed an LMI anisotropy feature of the (110) plane in rutile-TiO₂ single crystal. The photoelectricity exhibits notably anisotropy, where a significantly higher current response is observed along the y-axis direction. The light absorption and irradiation enhancements have been reflected in Raman intensity variations, indicating a stronger atomic vibration significantly modulates the electron density wave function along y-axis, leading to an increase of hot electrons incoherent transport. Meanwhile, electron–phonon scattering intensifies due to the coupling between low-effective-mass electrons. Thereby, hot electrons preferentially transport along the y-axis rather than the x-axis, ultimately leading to an LMI anisotropy. Our investigation provides an intriguing insight for potential optimization in broadly light–matter reactions.

Hydrogels offer promising solutions across various fields. However, understanding complex behaviors like swelling and ligand interaction requires multiperspective data, from functional groups to molecular dynamics. Single-perspective analyses often fall short, especially when ligand-induced selective adsorption occurs. This study presents a data-driven approach integrating TD-NMR, ¹H–¹⁵N HSQC, ¹H–¹³C HNCO with isotope-labeled peptides, RDKit descriptors, and DSC data. Using symbolic regression, we derived highly accurate, interpretable equations (e.g., swelling ratio accuracy = 1.0 on test set). This methodology reveals fundamental hydrogel mechanisms and provides a framework for rational design.

Conventional semiconductors typically have dominant bonding states near the valence band maximum (VBM) and antibonding states near the conduction band minimum (CBM). Semiconductors with the opposite electronic configuration, namely, VBM with dominant antibonding nature and CBM with dominant bonding nature (“AVBC semiconductors” for brevity), were theoretically proposed to exhibit excellent optoelectronic properties because of defect tolerance. However, no AVBC semiconductors have been identified so far. Here, we use high-throughput computation to identify over 100 AVBC semiconductors and analyze the transition metal dichalcogenide MX₂ (M = Hf, Zr; X = S, Se) family in detail. In addition to verifying their defect tolerance for both electrons and holes using first-principles simulations, we discovered that photoexcitation of charge carriers can lead to significant lattice stiffening and increased thermal conductivity, which can potentially be used as photodriven thermal switches. Our work analyzed the formation of the AVBC electronic structure and showcased the unusual photoinduced lattice dynamics.