AbstractThe synthesis of low‐dimensional metal nanocrystals with precise atom‐to‐nanoscale structure control is crucial for modulating their physicochemical properties. Traditional synthetic routes encounter challenges due to isotropic metallic bonding, which leads to limited control over metal nanostructures. Herein, a versatile approach is developed using various 2D material (2DM) nanoconfinements to produce a wide range of metal nanocrystals with controllable morphologies. Utilizing graphene oxide (GO) and Ti3C2Tx MXene nanosheets, thin multilayer films are assembled through vacuum filtration and are crosslinked with tetraammineplatinum(II) nitrate (TPtN), followed by in situ thermal reduction. By controlling the concentration of TPtN solution, precise loadings of platinum (Pt) are attained while preserving the nanoconfinement integrity. Two water removal techniques, air‐drying and freeze‐drying, are investigated to assess their impacts on resultant morphologies of Pt nanocrystals. Transmission electron microscopy and molecular dynamics simulations demonstrate high‐aspect‐ratio Pt nanosheets on MXene substrates and few‐atom Pt nanoclusters on GO substrates. A decrease in size distribution is observed upon the use of freeze‐drying. In the semihydrogenation reaction of phenylacetylene, freeze‐dried Pt–MXene heterostructures achieve a high turnover frequency of 2.93 s−1. This comprehensive study highlights the potential of utilizing 2DM nanoconfinement to synthesize metal nanostructures for catalysts and beyond.

AbstractStrain is an effective means of tuning the crystal structure to obtain a variety of fascinating properties, but how to apply flexible strain to meet the different needs of the film at each location has rarely been reported. In this study, a novel approach for designing strain‐damping structures that facilitate the imposition of flexible strain is introduced. A wide range of strain modulation is demonstrated in SmCoO3 films (a‐axis:+4.5%–+1.7%, b‐axis: +3.2%–+0.4%, c‐axis:+2.2%–+1.4%) under positive pressure by introducing Sm2O3 as a dopant. When SmCoO3 films are subjected to triaxial tensile strain, they exhibit a ferroelectric polarization of 7.12 µC cm−2. Through positive pressure modulation, resulting in a further increase in the ferroelectric polarization (up to 11.62 µC cm−2, which represents the maximum performance of the orthogonal rare earth transition metal oxide family). Moreover, the electron spin order can be effectively controlled, and the film's saturation magnetization increases to 14.83 emu cm−3 (+94.1%). This damping structure allows for flexible modulation of chemical strain in epitaxial film, achieving a delicate balance between film strain and structure, which provides valuable insights for all ferroelectrics based on structural distortion.

AbstractInterface strain significantly affects polarization in ferroelectric devices. In this paper, an innovative strategy is proposed to substantially enhance ferroelectric polarization using an ultra‐thin “soft‐buffer‐layer” (SBL), which reduces dislocation density and increases the tetragonality of ferroelectric thin films because of small elastic constants of Ti3Al along x and y axes. And in this work, it is demonstrated that PbZr0.4Ti0.6O3 (PZT) thin films are perfect c‐axis‐oriented epitaxial structures on (001) SrTiO3 (STO) substrates. The PZT capacitor with Ti3Al buffer layer exhibits a remarkable remnant polarization, reaching up to 131.93 µC cm−2 at an applied voltage of 5.00 V. Surprisingly, under the clamping effect of SrRuO3 and STO, Ti3Al films exhibit cubic structure and facilitate matching to the PZT film. It is proposed that the introduction of the Ti3Al buffer layer notably improves the tetragonality (c/a) ratio from 1.002 to 1.024, and significantly enhancing the polarization. There is no doubt that this adjustment reduces dislocation density and decreases stress influence from STO substrate. Given these advantages, the SBL method presents a compelling option for epitaxial PZT films, and also for enhancing the physical properties of other functional thin film materials.

AbstractSingle‐atom catalysts (SACs) are becoming increasingly recognized as highly promising catalytic materials, distinguished by their exceptional atomic efficiency, superior selectivity, and elevated activity levels. This review offers a detailed and comprehensive overview of the recent advancements in SACs, focusing on synthesis strategies, photocatalytic energy conversion applications, and advanced characterization techniques. Various synthetic approaches for fabricating atomically dispersed catalysts are elaborated concisely, emphasizing the importance of achieving precise atomic regulation on compatible supports to ensure strong metal–support interactions. Furthermore, the advanced characterization techniques by analytical tools are illustrated for a deep exploration of catalytic activity and mechanistic insights into uniformly dispersed SACs. Specifically, different kinds of support materials such as metal–organic frameworks (MOFs), their subset zeolitic imidazolate frameworks, and graphitic carbon nitride (g‐C3N4) with diverse coordination and electronic environments are examined. Further, advances in computational techniques and machine learning are transforming SACs development by improving predictive accuracy and reducing trial‐and‐error methods, thereby accelerating the discovery of stable and active catalysts. Finally, current challenges and prospects of SACs based on MOFs, and g‐C3N4 are addressed, providing valuable insights for the continued development and application of these catalysts in various industrial processes and environmental remediation efforts.

AbstractPoly(arylene ether nitrile)s (PAENs) appended with Zn(II)‐porphyrin in varied molar percentages (5% and 10%) are developed as dual colorimetric and fluorometric sensors for highly sensitive and selective cyanide (CN−) detection. The materials, DP‐5%PAEN@Zn and DP‐10%PAEN@Zn, exhibit significant Soret band shifts at 420 ± 2 nm, accompanied by the appearance of a new absorption band at 436 ± 2 nm, indicating strong CN− binding with high association constants of 1.3 × 10⁴ M−¹ and 2.3 × 10⁴ M−¹, respectively. A prominent color change from purple to green allowed for naked eye detection. Spectrofluorimetric studies revealed turn‐off fluorescence with Stern‐Volmer constants (Ksv) of 99.85 × 103 M−¹ for DP‐5%PAEN@Zn and 121.08 × 103 M−¹ for DP‐10%PAEN@Zn, achieving limit of detection (LOD) of 0.177 and 0.099 ppb, respectively. DP‐10%PAEN@Zn demonstrated excellent sensitivity and selectivity toward CN−, and also reusability, as it remained functional after ten TFA treatment cycles. The mechanistic investigation, supported by photophysical, electrochemical, and DFT analyses, revealed a photoinduced electron transfer process via static quenching. Material stability is confirmed through photodegradability, prolonged time, temperature, and humidity testing. Prototype test kits are developed for real‐time visual CN− detection in remote and environmental samples (tap, lake, sewage, and soil). Additionally, a smartphone‐based color recognition assay is implemented for qualitative and quantitative analysis.

AbstractLithium is being recognized as a strategic resource on a global scale, mainly because of its growing importance in the production of lithium‐ion batteries for electric vehicles and energy storage systems. Due to its uneven geographical distribution and limited availability on Earth, extracting lithium from brines and seawater presents a sustainable supply pathway. However, conventional lithium extraction techniques are still challenging, necessitating significant costs and energy consumption. This study primarily employs a solar‐utilizing selective extraction strategy for efficient lithium harvesting by designing a solar‐thermal sandwich sieve structure. Herein, a portable solar‐driven lithium extraction device has been developed based on HKUST‐1 and LIG. Due to the sub‐nano channels provided by HKUST‐1, the hydrated Li+ can selectively pass through the MOF layer. The excellent solar heating of the layer enables the device an accelerate vapor escaping, it then facilitates the delivery of Li+, resulting in lithium accumulation at the interface for convenient collection. The maximum lithium extraction capacity in one cycle is 1467 mg m−2, demonstrating good Li+ selectivity absorption with a high Mg2+/Li+ ratio under 1 solar illumination. Moreover, the device shows excellent cycle stability. This work offers an integrated solar utilization for scalable and sustainable lithium extraction from brine water.

AbstractCovalent organic frameworks (COFs), characterized by their high porosity and stability, hold great potential for applications in gas separations. However, achieving precise size sieving without hindering the gas diffusion rate is challenging. This study presents a novel approach to establishing tunable localized electric fields in COF channels to achieve efficient CO2 separation in Pebax‐based mixed matrix membranes (MMMs). Different charge densities of the localized electric field are achieved by the host–guest interaction between COF and varying charged ionic liquids (ILs). Remarkably, the MMM with a positive localized electric field attains the optimal CO2/CH4 separation performance with a significantly enhanced permeability (≈38%) and selectivity (≈99%), surpassing the Robeson upper bound. Through density functional theory (DFT) calculations, the enhanced CO2/CH4 selectivity of MMM is due to the “sieving effect” of a positive localized electric field on CO2 over CH4. Specifically, the negatively charged O atom in CO2 exhibits stronger electrostatic interaction than the positively charged H atom of CH4. Therefore, the strategy of regulating the localized electric field can be employed as an efficient design for CO2 separation in MMMs.

AbstractThe quality of P‐N heterojunction is crucial for the performance of antimony selenide (Sb2Se3) solar cells and thus attracting urgent attention. In this work, the monovalent cation Ag+ is doped in CdS, which enhances the N‐type conductivity of CdS film anomalously and reduces its parasitic absorption simultaneously. Furthermore, Ag doping of CdS promotes the diffusion of Cd into the Sb2Se3 layer, forming CdSb defects, which enhances the P‐type conductivity of Sb2Se3 and reduces the density of deep‐level centers. With further chemical etching treatment on the CdS surface, the quality of the CdS/Sb2Se3 P‐N heterojunction is distinctly improved, making the energy band alignment of CdS/Sb2Se3 more favorable for carrier transportation. Finally, a remarkable efficiency of 8.14%, which is the highest efficiency among those with Jsc of 30.96 mA cm−2, is achieved for vapor transport deposition processed Sb2Se3 solar cells. This work provides a strategy to simultaneously optimize the CdS and Sb2Se3 functional layers and enhance the quality of P‐N heterojunction for efficient Sb2Se3 solar cells.

AbstractThis research reports on the control of short‐term and long‐term memory in transition metal oxides embedded with localized gold nanoparticles (Au‐NPs). The HfTiOx/TiSiOx switching layer, after the orderly and uniform insertion of Au‐NPs, demonstrates uniform cycle‐to‐cycle DC switching with an ON–OFF ratio >10. Stable low‐resistance states (LRS) and high‐resistance state (HRS) are maintained up to 104 s with multilevel memory characteristics due to the control of oxygen vacancy concentrations. The localized Au‐NPs enhance the local electric field near the HfTiOx/Au‐NP interface, forming controlled conductive filaments, while the high concentration of oxygen vacancies creates a permanent conduction path inside TiSiOx after the electroforming process. The ITO/HfTiOx/Au‐NP/TiSiOx/TaN memristor exhibits stable, controllable gradual bipolar switching and mimics several biological memory functions, including pulse‐width‐dependent plasticity, spike‐timing‐dependent plasticity, pulse‐frequency‐dependent plasticity, and experience‐dependent plasticity. Additionally, a performance of 50k SET/RESET cycles without any significant degradation is achieved and the facilitation of long‐term potentiation/depression are demonstrated. With the help of controlled oxygen vacancy generation on the surface of Au‐NP inside the HfTiOx/TiSiOx switching layer, the memristor can emulate metaplasticity. Evaluation of a reservoir computing system utilizing the volatile switching of the memristor shows efficient processing of temporal data information which is essential for neuromorphic systems.

AbstractProximity‐orientation effects (POE) are essential for enzymes, as the spatial arrangement and orientation of catalytic sites strongly influence substrate binding and enhance catalysis. However, nanozymes often face limitations due to weak POE arising from uniform catalytic interfaces. Herein, Co atoms are incorporated into the lattice of Pt‐based nanozymes, exploiting differences in electron configuration and atomic radius between transition metals and noble metals. This integration induced lattice distortion formed new catalytic sites, and restricted the transport path, thereby enhancing the POE. Such transition metal‐doped alloy nanozyme (TANzyme) can be functioned as a self‐cascading nanozyme with artificial catalase‐oxidase activity. Density functional theory calculations demonstrated that the Pt site selectively decomposed H2O2 into H2O and O2, while the Co site specifically adsorbed O2 and conversed into superoxide anions, so an oxygen transfer path to connect dual‐active centers not only increased the POE but also improved catalytic specificity. Additionally, by leveraging the efficient catalytic property of TANzyme, a visual origami‐based sensing strategy is developed for the cascade detection of H2O2, nucleic acids, and marine toxins. This strategy highlighted the pivotal role of POE in enhancing the catalytic specificity of nanozymes, mimicking natural POE in enzymes, and providing a solution to design next‐generation nanozymes.