Seung Gyo Jeong, Bonnie Y. X. Lin, Mengru Jin
et al.
Abstract Interfacial polarization – charge accumulation at the heterointerface – is a well-established tool in semiconductors, but its influence in metals remains unexplored. Here, we demonstrate that interfacial polarization can robustly modulate surface work function in metallic rutile RuO2 layers in epitaxial RuO2/TiO2 heterostructures grown by hybrid molecular beam epitaxy. Using multislice electron ptychography, we directly visualize polar displacements of transition metal ions relative to oxygen octahedra near the interface, despite the conductive nature of RuO2. This interfacial polarization enables over 1 eV modulation of the RuO2 work function, controlled by small thickness variations (2-3 nm), as measured by Kelvin probe force microscopy, with a critical thickness of ~4 nm – corresponding to the transition from fully-strained to relaxed film. These results establish interfacial polarization as a powerful route to control electronic properties in metals and have implications for designing tunable electronic, catalytic, and quantum devices through interfacial control in polar metallic systems.
Summary: The importance of recycling lithium-ion batteries is growing within the battery supply chain as a promising answer to economic and environmental challenges. Many initiatives are in progress to improve battery recycling technologies, as existing methods encounter major obstacles. Here, we report a polyol-metallurgical recycling process to upgrade polycrystalline cathodes to single-crystal cathodes, while detailing the coprecipitation and cathode resynthesis steps. Using citric acid and ethylene glycol enables effective leaching, simple separation, and controlled coprecipitation. Leveraging the distinct poly-esterification reactions in the precipitation phase, we achieve precise control over morphology and particle sizes. Using the coprecipitates, we have successfully resynthesized a LiNi0.6Co0.2Mn0.2O2 cathode with a similar elemental composition compared to the pristine cathode, free of impurities, and exhibiting a single-crystal morphology featuring grain sizes in the range of 10 μm. The study showcases the potential of polyol metallurgy as a novel and efficient method for recycling lithium-ion batteries and synthesizing advanced cathode materials. Science for society: Lithium-ion batteries power electric vehicles, portable devices, and renewable energy storage, however, their production and disposal create significant environmental and economic challenges. Recycling spent batteries and manufacturing scraps is essential for conserving critical resources such as nickel, cobalt, and manganese, while minimizing waste. However, conventional recycling methods are complex, water-intensive, and often introduce impurities that lead to quality control issues in resynthesized cathode materials. This study introduces a simplified polyol-metallurgical recycling process that uses a citric acid-ethylene glycol solution for both leaching and coprecipitation in cathode recycling. This dual-function approach eliminates complicated separation processes and avoids the introduction of impurities. The resulting precursors maintain the original chemical composition of the cathode and enable precise control over particle morphology. By applying this process to degraded NMC622 cathodes, we successfully synthesized single-crystal cathodes featuring controlled particle sizes, uniform composition, minimal structural defects, and improved electrochemical performance. The implications of this work go beyond recycling, offering a pathway to produce advanced cathode materials from waste streams, reinforcing a circular economy in battery production. By upgrading polycrystalline cathodes into single-crystal materials with high quality and guaranteed performance, the method advances multi-functional approaches to battery recycling. This innovation addresses both sustainability and performance challenges, providing the industry and society with a cleaner, more efficient solution for recovering and reusing battery materials.
Robert Kennedy Otieno, Edward V. Odhong, Alex Munyasia Muumbo
The future calls for smart, sustainable, high‑performance, biodegradable materials that integrate seamlessly into biomedical and engineering applications. Magnesium oxide (MgO)-coated graphene nanoplatelet (GNP) reinforced AZ91 matrix composites have emerged as a promising candidate. However, persistent challenges of poor wettability and unstable interfacial bonding hinder their potential. These shortcomings restrict efficient load transfer and uniform dispersion. This systematic review of transformative, cutting-edge research provides a consolidated foundation for future experimental and computational breakthroughs that unlocks new horizons in biomedical and engineering applications. It uniquely synthesizes advances in wettability enhancement, interface engineering, and fabrication approaches, identifying critical challenges and charting pathways for sustainable performance. Methodological robustness was ensured using validation technique that relied on multiple databases of Scopus and Web of Science. Strong thematic consistency across databases was found through comparative analysis of keywords, sources, and authors. Structured literature search and eligibility evaluation was done using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. Peer-reviewed articles of 106 articles of 388 authors in the period of 2010–2025 were analysed and organized into four refined thematic clusters: (1) wettability enhancement of MgO-coated GNPs, (2) interface engineering, (3) fabrication and dispersion routes, and (4) biomedical applications. The evidence highlights their unique ability to enhance wettability, suppress detrimental interfacial reactions, and achieve strength–ductility synergy through semi‑coherent interfaces. Looking ahead, this review identifies new frontiers in adaptive interfaces, real‑time diagnostics, AI‑guided optimization, and multifunctional surface engineering, providing a roadmap for scalable and sustainable design of next‑generation MgO‑coated GNP reinforced AZ91 composites.
Anisotropic stimuli-responsive polymeric materials (ASRPM) exhibit distinct physical and chemical properties along various orientations and can respond to external stimuli, demonstrating exceptional adaptability and functional integration capabilities. As research advances, new discoveries and applications continue to emerge, further enhancing the appeal of these materials. Despite an increase in related publications, there remains a relative scarcity of systematic summaries. In this mini-review, we summarize the research advancements in this field over the past decade, focusing on the structural properties, fabrication methods, advantages, and potential applications of ASRPM. We present a synthesized overview through illustrative charts, aiming to provide readers with a representative snapshot of the dynamic research landscape.
Abstract Optoelectronic synapses can be crucial for advancing artificial intelligence and visual systems. Optoelectronic synapses based on organic field-effect transistors have been widely studied but still face significant challenges including obvious programming nonlinearity, restricted response wavelength, high operation voltage, and limited storage memory. Organic electrochemical transistors can be another candidate but lack intensive studies. Additionally, wafer-scale photolithographic fabrication on optoelectronic synapses responding to near-infrared (NIR) light is highly desirable but rarely reported. Here, we propose the NIR organic photoelectrochemical transistor (OPECT) array capable of low voltage multi-level memories fabricated by photolithography. Based on NIR photo-induced electrochemical doping mechanism, the OPECTs enable linear weight programming with ultra-low nonlinearity (−0.015) over a wide range (47.3). We further demonstrate OPECTs arrays for image sensing, memorization, and visualization. Eventually, a convolutional computing system is constructed, executing accurate recognition of noisy handwritten digits. This work offers a promising insight into neuromorphic sensory computing applications.
Characterization of tea volatile substances is important for tea quality assessment, flavor evaluation, and manufacturing process control. In this work, an online monitoring system was developed and directly coupled with soft ionization by chemical reaction in transfer (SICRIT) ion source. Tea samples were roasted online at 160 °C, and the generated vapors were transferred to the SICRIT source for real-time ionization and high-resolution mass spectrometry (MS) detection. The results showed progressive release of numerous volatile compounds during the roasting process. Distinctive mass spectral profiles were observed at different time intervals, and teas with varying fermentation degrees exhibited different chemical fingerprints. The detected compounds included N-heterocyclics, esters, amines, alcohols, amino acids. Some are characteristic tea flavor compounds while others are Maillard reaction products. Multivariate data analysis clearly differentiated tea samples based on the acquired mass spectral data. With its miniaturized design and simple operation, SICRIT demonstrated excellent performance for direct analysis of odor compounds. The integrated SICRIT-MS system enabled direct, real-time analysis of volatile compounds through continuous vapor generation, transfer, and ionization, providing a simple and efficient analytical approach that requires no sample pretreatment or front-end separation.
To save energy and reduce CO2 emissions, the lightweight design of structural components has recently become a global issue. Fe–Mn–Al–C based alloys with a low mass density have received considerable attention as structural materials enabling such lightweight designs. However, typical strength-ductility trade-off dilemma appears in Fe–Mn–Al–C lightweight steels. Dispersion of nano-sized Fe3AlC-type κ-carbides achieves excellent tensile properties of high strength (∼1 GPa) and large elongation (∼50 %). However, further increase in strength (∼1.2 GPa) caused by κ-carbide coarsening reduces elongation significantly (<10 %), limiting the potential applications of lightweight steels in structural parts that require ultrahigh strength and high ductility, such as wear-resistant components. Here, we resolve this drawback of lightweight steels by reinforcing the surface layer through 3D printing. The composition of base steel plate is Fe–30Mn–8Al-0.7C (wt%), and a lightweight steel powder with a relatively higher Al and C contents (Fe–30Mn-9.5Al-1.0C (wt%)) was then deposited on the surface of base steel plate through laser powder bed fusion (L-PBF). After L-PBF, an aging treatment led to more precipitation of κ-carbides in the surface layer, producing a functionally graded hard surface layer. A developed surface-hardened ductile lightweight steel thus has the potential to replace conventional wear-resistant steels, as it has excellent tensile ductility (51 %), high surface hardness (410 HV), high wear resistance, and 12 % lower mass density.
Abstract Direct damage evolution simulations based on electronic structure physics show a significant correlation between Cr concentration and polymorphism in the form of localized formation of C15 Laves phase structures in Fe–Cr alloys under irradiation. We elucidate the role of Cr content in the formation and stabilization of the C15 Laves phase structure, which is crucial to understanding the behavior of materials under extreme conditions. This study also reveals a connection between non-linear magnetic behavior and irradiation-induced swelling in Fe–Cr alloys. These results advance the comprehension of radiation-induced changes in magnetization and suggest a novel experimental approach for detecting C15 clusters in irradiated Fe–Cr alloys.
The aim of this work is to study the phase transformations, microstructures, and mechanical properties of martensitic stainless steel (MSS) 410 deposits produced by laser powder-directed energy deposition (LP-DED) additive manufacturing. The LP-DED MSS 410 deposits underwent post-heat treatment, which included austenitizing at 980 °C for 3 h, followed by different tempering treatments at the temperatures of 250, 600, and 750 °C for 5 h, respectively. The analyses of phase transformations and microstructural evolutions of LP-DED MSS 410 were carried out using X-ray diffraction, SEM-EDS, and EBSD. Vickers hardness and tensile strength properties were also measured to analyze the effects of the different tempering heat treatments. It revealed that the as-built MSS 410 has very fine lath martensite, high hardness of about 480 HV<sub>1.0</sub>, and tensile strength of about 1280 MPa, but elongation was much lower than the post-heat-treated ones. Precipitations of chromium carbide (Cr<sub>23</sub>C<sub>6</sub>) were most commonly observed at the grain boundaries and the entire matrix at the tempering temperatures of 600 °C and 750 °C. In general, the tensile strength decreased from 1381 MPa to 688 MPa as tempering temperatures increased to 750 °C from 250 °C. Additionally, as the tempering temperature increased, the chromium carbide and tempered martensite structures became coarser.
This research aims to investigate the application of the hot pressing (HP) sintering process in the fabrication of W-B-Fe-Cr-C advanced shielding materials and analyze the relationship between their microstructure and mechanical properties. The findings reveal that the HP sintering process can effectively produce reactive sintered boride (RSB) materials with high density and engineering application size. The results indicate that the residual stress in RSB-HP improves its bending strength to some extent. Residual stress and granular structure are both related to phase aggregation during sintering. Microstructural analysis has unveiled the granular organizational characteristics and the pathways of crack propagation within the RSB-HP. These discoveries hold significant importance for comprehending the potential of the HP sintering process in the context of nuclear fusion shielding material preparation and provide a scientific foundation for further optimizing the sintering process and performance of RSB materials.
The traditional small molecular rubber antioxidants have the shortcomings of single function, toxicity, and heavy dependence on non-renewable fossil resources, which limits their green, high-efficiency, and sustainable development in the rubber industry. To address this problem, in this work, we first developed a chitosan derivative containing 10-undecenoyl groups (COS-UC) and then combined it with the natural small molecular antioxidant gallic acid (GA) to prepare chitosan derivative containing 10-undecenoyl and galloyl groups (COS-UC-GA). The obtained COS-UC-GA was used as multifunctional modifier and applied in styrene-butadiene rubber (SBR)/silica composites. The effects of COS-UC-GA on the curing characteristics, crosslinking density, morphology, mechanical properties, and interfacial interaction of SBR/silica composites were explored in detail. The results indicated that the COS-UC-GA can effectively accelerate the vulcanization process of SBR/silica compounds, promote the uniform dispersion of silica, improve the mechanical properties of SBR/silica composites, and significantly enhance the interfacial interaction between the silica and rubber. This research provides a new perspective for developing green and eco-friendly multifunctional modifiers, which not only contributes to the comprehensive utilization of biomass resources, but also can promote the green development of the rubber industry.
In recent years, calcium peroxide (CaO2) has attracted widespread attention in the medical community due to its excellent antitumor and antibacterial properties, and has gradually become a hot research topic in the biomedical field. CaO2 reacts with water (H2O) to produce calcium ion (Ca2+), oxygen (O2), and hydrogen peroxide (H2O2), where Ca2+ is suitable for calcium death caused by calcium overload, O2 is suitable for O2-dependent anticancer therapy, and H2O2 is suitable for H2O2-dependent anticancer therapy. In addition, H2O2 can also be used in the antibacterial field to treat bacterial infections. All these make the CaO2 to become a kind of excellent antitumor and antibacterial drug. This study mainly reviews the preparation and surface modification of CaO2, probes into the latest progress about CaO2 nanoparticles in the field of tumor treatment and antimicrobial therapy. Finally, the challenges that CaO2 still faces in the future research field are clarified, and its prospects are forecasted.
X-ray sources are developing rapidly and their coherent output is growing correspondingly. The increased coherent flux from modern X-ray sources is being matched with an associated development in experimental methods. This article reviews the literature describing the ideas that utilize the increased brilliance from modern X-ray sources. It explores how ideas in coherent X-ray science are leading to developments in other areas, and vice versa. The article describes measurements of coherence properties and uses this discussion as a base from which to describe partially coherent diffraction and X-ray phase-contrast imaging, with applications in materials science, engineering and medicine. Coherent diffraction imaging methods are reviewed along with associated experiments in materials science. Proposals for experiments to be performed with the new X-ray free-electron lasers are briefly discussed. The literature on X-ray photon-correlation spectroscopy is described and the features it has in common with other coherent X-ray methods are identified. Many of the ideas used in the coherent X-ray literature have their origins in the optical and electron communities and these connections are explored. A review of the areas in which ideas from coherent X-ray methods are contributing to methods for the neutron, electron and optical communities is presented.
Manipulating fluorescence color to achieve patterned function may access to many applications and remains some challenges. In this work, we provide an effective way to manipulate upconversion fluorescence through the photonic crystals. The structure of the photonic crystals (PCs) has a regulatory effect on upconversion fluorescence. We assembled NaYF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs) with SiO2 and CdS photonic crystals respectively to obtain the photonic crystals/upconversion nanoparticles (PCs/UCNPs) composites. We studied the manipulating mechanism of two kinds of photonic crystals on upconversion fluorescence, and realized patterning application. This study provides a new way to realize information coding, patterned display of fluorescence manipulating.