Physics

ABSTRACT Hydrogel electrolytes are crucial for advancing safe and flexible aqueous zinc‐ion batteries. However, conventional homogeneous hydrogels suffer a trade‐off between fast Zn 2+ transport and stable Zn/electrolyte interfaces. Herein, we report a surface energy‐driven self‐regulated gradient hydrogel electrolyte (SRG‐HE) that resolves this conflict via a spatially modulated polymer network. The SRG‐HE shows dense layers at the Zn/SRG‐HE interfaces provide robust passivation, while a low‐density bulk supports rapid Zn 2+ diffusion. During in situ polymerization, amphiphilic Triton X‐100 induces spontaneous component migration and surface enrichment, forming a symmetric surface–bulk–surface gradient. The dense surface layers suppress free‐water activity to stabilize interfaces, whereas the hydrated bulk delivers high ionic conductivity (97.7 mS cm − 1 ). Polar groups in SRG‐HE further immobilize OTf − , enabling selective Zn 2+ transport with a high transference number of 0.88. Consequently, Zn||Zn cells cycle stably for 1365 h at 4 mA cm − 2 with uniform (002)‐textured deposition. When paired with V 2 O 5 cathodes, the full cells maintain a reversible capacity of 234 mAh g − 1 after 2000 cycles at 1000 mA g − 1 , achieving near 100% Coulombic efficiency. Even under mechanical deformation, SRG‐HE‐based pouch cells retain functionality, underscoring their potential for durable, high‐performance energy storage systems.

Thiolated polymers represent a versatile class of bioinks for extrusion-based 3D bioprinting, combining cytocompatibility with tunable crosslinking chemistry and dynamic redox-responsive behaviour. This review consolidates recent advances in thiomer chemistry, focusing on synthetic strategies that modulate thiol reactivity through pKa adjustment, neighboring-group interactions, and redox control. Crosslinking mechanisms such as oxidative disulfide formation, thiol-ene, thiol-yne, and thiol-polyphenol reactions are compared in terms of their impact on gelation. External triggers, including small-molecule and polymeric crosslinkers, light activation, oxidants, enzymatic systems, as well as hybrid dual-stage systems, are discussed for their capacity to achieve controlled gelation and long-term stability. A comprehensive printability framework links chemical design to performance metrics such as gel point, modulus build-up rate, collapse angle, filament fusion index, fidelity ratio, and shear thresholds that maintain cell viability. Redox-driven reversibility provides additional adaptability through self-healing and stress-relaxation mechanisms. Applications span soft tissue and cartilage regeneration, vascularized and multicellular constructs, hemostatic adhesives, and extracellular matrix-mimetic scaffolds for stem-cell culture. These developments collectively establish design principles for balancing gelation kinetics, shape fidelity, and biological functionality in thiomer-based bioinks.

ABSTRACT MXenes, a rapidly expanding family of two‐dimensional transition metal carbides, nitrides, and carbonitrides, are versatile nanomaterials with broad applications in energy, catalysis, sensing, and biomedicine. While most studies have focused on mono–transition‐metal MXenes (e.g., Ti 3 C 2 T x ), recent advances have enabled the synthesis of double‐transition‐metal (DTM) MXenes, in which two distinct transition metals occupy ordered or disordered atomic arrangements. This added compositional and structural complexity broadens property range, enabling enhanced oxidative stability, programmable degradation behavior, tunable electromagnetic responses, and improved near‐infrared optical absorption. These attributes position DTM MXenes as a compelling biomedical materials platform. In this review, we summarize the discovery, synthesis strategies, and physicochemical characteristics of DTM MXenes, with systematic comparisons to classical mono–transition‐metal MXenes to elucidate multi‐metal structure–property relationships. We then critically examine emerging biomedical applications of DTM MXenes, including photothermal cancer therapy, multimodal imaging, drug delivery, antibacterial activity, and tissue engineering, highlighting insights from both in vitro and in vivo studies. Key challenges for clinical translation, including scalable synthesis, compositional and structural control, long‐term biocompatibility, biodegradation, and regulatory considerations, are discussed. By integrating perspectives from materials science, nanotechnology, and biomedical engineering, this review outlines opportunities, limitations, and future directions toward safe, effective multifunctional DTM MXene nanomedicine platforms.

Biological skin is among the most sophisticated organs and mediates essential sensory function. Inspired by its structure and function, skin-integrated flexible sensing systems have developed rapidly and demonstrated significant utility in applications such as closed-loop robotic control, human-machine interaction, and health monitoring. These systems typically comprise sensing components and electrodes/circuits for signal acquisition, transmission, and processing, that can provide direct feedback to users or support control signals to actuators. A central objective in this field is the integration of appropriate flexible materials to fabricate functional units that optimally balance response sensitivity and mechanical compliance for special scenarios. This review systematically summarizes sensing components for mechanical stimuli (pressing, stretching, bending, and twisting) and evaluates material selection and optimization strategies according to distinct transduction mechanisms, including capacitive, piezoelectric, resistive, triboelectric effects, etc. Besides, the review investigates the design and layout of flexible signal-acquisition electrodes and processing circuits, and surveys recent progress in deformation-invariant high-conductivity materials. Specific applications in electrophysiological monitoring and physicochemical sensing of biological fluids are discussed in detail. Finally, the review highlights current challenges and future perspectives to guide material development, optimization, and applications of next-generation intelligent electronic skins.

ABSTRACT Development of high‐performance SmCo magnets, simultaneously possessing high magnetic energy product ( BH ) max and low remanence temperature coefficient | α |, is critical for applications of wide‐temperature precision instruments. Conventional heavy rare‐earth (HRE) substitution improves temperature stability via antiferromagnetic coupling but inevitably sacrifices ( BH ) max , resulting in a persistent trade‐off between ( BH ) max and | α |. Herein, we propose a Fe‐HRE synergistic compositional‐design strategy that integrates Fe enrichment and HRE segregation to break this bottleneck. First‐principles calculations reveal that increasing Fe concentration provides a thermodynamic driving force for HREs segregation from the 1:5H cell boundary into the 2:17R matrix. Furthermore, molecular field simulations quantitatively demonstrate that HRE enrichment in the 2:17R phase enhances its temperature compensation effect and effectively overcomes this trade‐off. Guided by these insights, a series of Sm 0.4 Gd 0.6 (Co bal Fe x Cu 0.08 Zr 0.025 ) 7.2 ( x = 0.20–0.24) magnets are prepared. Magnetic and microstructural characterizations confirm that moderate Fe enrichment ( x = 0.22) not only improves ( BH ) max but also facilitates Gd segregation into 2:17R phase without microstructural degradations. These synergistic effects yield a record‐high ( BH ) max of 18.8 MGOe and α 20°C–300°C = −0.012%/°C. This work establishes a unified design framework integrating magnetic moment engineering with thermodynamic element distribution regulation, paving a viable path for high‐temperature‐stable SmCo magnets for aerospace precision instruments.

ABSTRACT Rational regulation of lithium polysulfide reaction kinetics, coupled with strategies for stabilizing the Li anode, constitutes a cornerstone for lithium–sulfur (Li–S) chemistry. Herein, we propose phthalocyanine (Pc) as a homogeneously dispersed promoter in the electrolyte for Li–S batteries, based on its N 8 ‐cavity planar rigid structure featuring an electron‐rich macrocyclic core. Under the optimized concentration of Pc in electrolyte, we reveal that the Li─N coordination bonds between Li 2 S 8 and Pc in the catholyte of Li–S batteries, which significantly contribute to the catalytic conversion of sulfur species. Meanwhile, Pc molecules in the anolyte preferentially adsorb onto the Li anode surface, forming a dense molecular layer by virtue of Li─N bonding, which effectively enhances interfacial desolvation kinetics and thereby promotes uniform Li deposition. Enabled by the promoted Li–S chemistry through Li─N bonds, the battery with Pc enabler achieves a low decay rate of 0.0479% per cycle after 600 cycles at 1C. More remarkably, 1.07 Ah pouch cells deliver a high energy density of 325.5 Wh kg −1 , serving as a compelling design strategy for leveraging sustainable Li─N bond chemistry to achieve high‐rate and long‐life Li–S battery technology.

ABSTRACT Ferroelectric semiconductors show huge potential in photocatalytic overall water splitting (POWS), while achieving strong polarization remains challenging. Herein, we develop bipolar‐axis intergrowth ferroelectrics Bi 7 Ti 4 NbO 21 ( i BTN) with colossal polarization intensity and favorable reaction thermodynamics for efficient and stable POWS. Compared to conventional unipolar‐axis ferroelectrics Bi 3 TiNbO 9 and Bi 4 Ti 3 O 12 with symmetric stacking of structural units, the asymmetric stacking structure simultaneously induces prodigious dipole moments superimposed along the a ‐axis (3793.53 D) and interlayer dipole moments along the c ‐axis (106.39 D) within i BTN, establishing ultra‐strong orthogonal polarization fields. Thus, i BTN achieves the lowest exciton binding energy (43.62 meV), highest density of states, ultra‐low electron effective mass (0.010 m 0 ), and exceptionally high electron‐hole effective mass ratio ( m e / m h = 400), enabling synergistic enhancement across the entire photogenerated carrier dynamics process of “generation‐separation‐transport”. Simultaneously, ferroelectric polarization optimizes surface catalysis, allowing favorable adsorption characteristics and low POWS reaction energy barrier. Consequently, i BTN exhibits state‐of‐the‐art POWS rates among pristine ferroelectric photocatalysts, with stoichiometric H 2 and O 2 evolution rates of 73.31 and 37.34 µmol·h −1 , respectively. Outdoor tests present a stable POWS activity of i BTN for 50 h in 10 days, with a solar‐to‐hydrogen efficiency reaching 0.11%, demonstrating considerable practical potential. The development of multipole‐axis intergrowth ferroelectrics unlocks a new path toward efficient POWS.

Hydrogels, valued for their intrinsic biocompatibility and tunable mechanical properties, play a pivotal role in bioelectronics, biomedicine, and soft robotics. However, the intrinsic isotropy of conventional hydrogels limits their capacity to mimic the anisotropic architectures and directional functionalities of native tissues─hindering performance in applications requiring unidirectional force transmission, directional charge transport, or guided cell alignment. To address this, anisotropic hydrogels with spatially ordered architectures have emerged as transformative materials. This review systematically summarizes recent advances in the design and fabrication of anisotropic hydrogels, highlighting innovative strategies such as external-field-induced alignment and template-guided assembly, along with the integration of functional materials that enable precise molecular orientation and multiscale structural control. These engineered hydrogels exhibit programmable anisotropic responses─mechanical, electrical, and biological─unlocking new possibilities in flexible biosensing, intelligent actuation, targeted drug delivery, and tissue regeneration. Despite substantial progress, challenges remain in long-term structural stability, scalable manufacturing, biocompatibility of conductive fillers, and implementation of full-lifecycle design. Addressing these limitations through next-generation material innovations and fabrication technologies will be key to realizing the full potential of anisotropic hydrogels in advanced biointegrated systems.

We demonstrate plasma-etch terminated Cr2O3/β-Ga2O3 heterojunction diodes (HJDs) on a low-doped (mid-1015 cm−3) 20 μm thick halide vapor phase epitaxy-grown drift layer. Bilayer Cr2O3 was deposited by reactive RF sputtering using a metallic Cr target and by tuning the Ar/O2 gas flow ratio. 1.5 μm self-aligned mesa etch was carried out using dry-etch based chemistry to achieve effective edge termination. Circular devices with 60–300 μm diameter exhibited breakdown voltages in the range of 3–3.4 kV with an ultralow reverse leakage (10−5–10−6 A/cm2) current density before breakdown. High-voltage capacitance-voltage measurement was carried out to extract the charge density profile up to 10–12 μm. The variation of (ND-NA) was within ±5% up to 12 μm, exhibiting uniform and controlled low doping [(4–5) × 1015 cm−3] across the thick drift layer. This is the lowest controlled doping demonstrated for a thick drift layer in β-Ga2O3. Room temperature I-V measurement shows 50 A/cm2 current density at 5 V forward voltage with Ron,sp = 60 mΩ cm2 after considering current spreading. A thick drift layer with uniform doping, optimization of the sputtering condition of Cr2O3, and deep mesa etch for edge termination are all crucial to achieve multi-kV class Cr2O3/β-Ga2O3 HJDs.

A century after the discovery of superconductivity, the search for new superconductors still relies largely on trial and error, challenging researchers to identify the universal design principles that govern why certain materials superconduct at higher temperatures. Here, the authors introduce an interpretable, data-driven approach that pairs Random Forest screening with SISSO symbolic regression to reveal fundamental ``material genes'' governing Tc in conventional BCS superconductors. Unlike black-box predictors, this study reveals physically meaningful relationships that provide actionable guideline for high Tc: a near half-filled d-orbital per atom combined with moderate heterogeneity in unfilled orbitals.