While correlated phenomena of flat bands have been extensively studied in twisted systems, the ordered states that emerge from interactions in the intrinsic flat bands of kagome lattice materials remain largely unexplored. The newly discovered kagome metal CsCr3Sb5 offers a unique and rich platform for this research, as its multi-orbital flat bands at the Fermi surface result in a complex interplay of pressurized superconductivity, antiferromagnetism, a structural phase transition, and density wave orders. Here, using ultrafast optical techniques, we provide strong spectroscopic evidence for a charge density wave transition in CsCr3Sb5, resolving previous ambiguities. Crucially, we identify rotational symmetry breaking that manifests as a three-state Potts-type nematicity. Our elastoresistance measurements directly demonstrate the electronic origin of this order, as the rotational-symmetry-breaking E2g component of the elastoresistance shows a divergent behaviour around the transition temperature. This exotic nematicity results from the lifting of degeneracy of the multi-orbital flat bands, akin to phenomena seen in certain iron-based superconductors. Our study pioneers the investigation of ultrafast dynamics in flat-band systems at the Fermi surface, offering new insights into the interactions between multiple elementary excitations in strongly correlated systems.

Iron-based superconductors, particularly the 1111-type GdFeAsO system, represent a crucial platform for investigating unconventional superconductivity, yet optimizing critical parameters through advanced doping strategies remains challenging. This study innovatively introduces uranium doping at Gd sites to modulate electronic properties of GdFeAsO system. Through vacuum-assisted solid-state synthesis and comprehensive characterization, we demonstrate successful U substitution, as confirmed by the systematic lattice contractions along both a- and c-axes. The parent compound exhibits a pronounced resistivity anomaly around 128 K, associated with a spin-density-wave (SDW) transition. Notably, U doping potently suppresses this SDW instability, with superconductivity emerging in the doping range 0.05 <= x <= 0.2 and reaching a maximum critical temperature (Tc) of 48 K at optimal doping (x = 0.15). Magnetic studies corroborate the bulk superconductivity in this U-doped GdFeAsO system. For the x = 0.15 sample, the applied external field suppresses the superconducting onset temperature extremely slowly, indicating a considerably high upper critical field. Furthermore, the tetravalent state of U and modified charge environment reveal that U effectively introduces electron doping into this material. These results demonstrate the critical role of U-5f electrons in enhancing electron correlations and mediating the electron pairing interactions, collectively contributing to the emergence and optimization of Tc in this system. The layered Gd1-xUxFeAsO materials, with tunable carrier density, high Tc, and robust bulk superconducting properties, is a promising new platform for studying the fundamental physics of hightemperature superconductivity and developing high-performance superconducting devices.

Abstract The hydroxide exchange membrane fuel cell (HEMFC) is one of the most advanced fuel cells, showing high potential in fuel cell vehicles. In a HEMFC, the gas flow pattern and distribution are significant as air is introduced into flow field initially. However, few studies have focused on gas flow and no effective approach could predict and evaluate flow fields before they are manufactured. In this work, a novel approach based on a multi‐parameter function including pressure drop, velocity, and maldistribution factor was proposed to design and evaluate the hydrodynamics of flow fields. Models of nickel foam, single serpentine, and parallel flow fields were built via X‐ray computed tomography (CT) and direct fluid domain reconstruction. Numerical simulation with single‐phase flow was implemented to predict the pressure drop, velocity, and distribution. The pressure drop was validated experimentally with 3D printed plates and the relative error was less than 20%. The maldistribution factors (M f ) were proposed and calculated to estimate gas distribution. The M f of nickel foam flow field was 0.90–1.02, which was much lower than the M f of the parallel flow field (2.85–3.01) and the M f of the single serpentine (1.36–1.54). Combined with M f , average z velocity ( v z ), and pressure drop (P), the multi‐parameter‐function was proposed. The nickel foam flow field performed the best under single‐phase conditions.

This study achieves highly selective photoelectrocatalytic CO2 reduction to ethanol through plasmon-enhanced Cu2O/Ag photocathodes, overcoming inherent limitations of Cu2O including narrow light absorption and rapid charge recombination. The fabrication involved sequential electrodeposition on fluorine-doped tin oxide transparent conducting glass (FTO): CuSCN at-0.3 V vs. Ag/AgCl (0.1 mol/L CuSO4 center dot 5H(2)O, 0.1 mol/L ethylenediaminetetraacetic acid (EDTA), 0.1 mol/L KSCN) followed by Cu2O at-0.1 mA center dot cm(-2) (0.4 mol/L CuSO4, 3 mol/L lactic acid, pH 12.5). Triangular Ag nano-particles (AgNPs) synthesized via light-assisted reduction were deposited via drop-casting at 70 degrees C, with 100 mu L center dot cm(-2) identified as optimal loading. Comprehensive characterization validated the structure and mechanism: field emission transmission electron microscope (FE-TEM) confirmed epitaxial Ag(111)/Cu2O(110) growth; XPS revealed interfacial electron transfer via Cu(+)2p3/2 (931.04 -> 931.66 eV) and Ag 3d5/2(369.08 -> 368.52 eV) shifts; UV-Vis DRS demonstrated localized surface plasmon resonance (LSPR)-mediated absorption extension to 700 nm; and 40% PL quenching indicated suppressed recombination. Under AM 1.5G illumination in 0.1 mol/L KHCO3, the optimized photocathode achieved a photocurrent density of-2.02 mA center dot cm(-2) at 0 V vs. RHE, a 30% enhancement versus bare Cu2O (-1.56 mA center dot cm(-2)). Electrochemical analyses revealed increased carrier concentration (5.56x1016 cm(-3)) and reduced Tafel slope, signifying accelerated kinetics. Crucially, CO2 reduction at-0.2 V vs. RHE yielded ethanol with 81.3% Faradaic efficiency (0.358 mu mol center dot h(-1)center dot cm(-2)) while suppressing hydrogen evolution (<1% FE). Total carbon product FE exceeding 100% suggests participation of non-Faradaic catalytic cycles. Performance degradation at excessive loading (300 mu L center dot cm(-2); 32% photocurrent reduction) confirmed aggregation effects. Finite-Difference Time-Domain (FDTD) simulations corroborated the mechanism, showing 15-fold electromagnetic field enhancement at AgNPs tips under 600 nm illumination, aligning with peak Incident Photon-to-Current Efficiency (IP-CE). The record ethanol selectivity stems from synergistic LSPR effects: near-field enhancement facilitates *CO intermediate formation and adsorption, hot electron injection promotes multi-electron transfers crucial for C-C coupling, and the Ag/Cu2O Schottky barrier effectively suppresses parasitic hydrogen evolution reaction (HER). This work establishes a material design paradigm for efficient solar-to-fuel conversion targeting value-added multi-carbon products.

Doping engineering offers an effective route to tailoring light harvesting and charge-transfer properties for photocatalytic CO2 reduction. Herein, multiflower-like layered double hydroxide Ni1.5Co1.5Al-LDH assembled from interconnected nanosheets was synthesized via a facile hydrothermal method. The incorporation of an optimal amount of Co2+ and the induction of oxygen vacancies synergistically broaden the visible-light absorption range and accelerate the electron transfer rate. Under visible-light irradiation, Ni1.5Co1.5Al-LDH delivers a CO evolution rate of 761.19 mu mol & centerdot;g(-1)& centerdot;h(-1), which is 3.9 and 1.5 times higher than those of Ni3Al-LDH and Co3Al-LDH, respectively. Notably, Ni1.5Co1.5Al-LDH preserves the three-dimensional multiflower-like architecture of Ni3Al-LDH, providing accessible catalytic sites and shortening the charge-transport pathways. In addition, abundant vacancies promote the formation of Co2+-V-O Lewis acid-base pairs, enhancing CO2 adsorption and thereby contributing to the improved activity.

A metal-insulator transition (MIT) driven by bond order (BO) coupled with a secondary spin-density wave (SDW) is identified in CsCr_2S_2O. Such coupling is enabled as a result of the broken time-reversal symmetry due to the pre-existing C-type antiferromagnetic (C-AFM) order. First-principles calculations reveal an orbital-selective physics that Cr-d_yz orbitals form local moments and establish the altermagnetic order, while the Cr-d_xz orbitals remain metallic and hybridize with S-p_z. Thus the low-energy physics is governed by the Cr-d_xz and S-p_z orbitals. On-site interactions then enhance a secondary SDW (sSDW) instability of the itinerant d_xz electrons, which couples to the Cr-d_xz-S-p_z bonding order. The resulting coupled sSDW-BO simultaneously produces experimentally observed structural distortion, charge disproportionation, local Cr-moment modulation, and gap opening. Our results establish an orbital-selective mechanism upon which pre-existing altermagnetism and electronic correlations cooperate to drive a structural MIT.

Inorganic magnesium potassium phosphate (MKP) coatings offer rapid, zero-volatile organic compound (VOC) corrosion protection for steel structures. However, their application is impeded by insufficient mechanical strength and limited barrier durability. This study integrates calcium sulfate whiskers (CSWs) into a sprayable MKP matrix. Unlike conventional polymeric or metallic fibers, CSWs demonstrate excellent chemical compatibility with the MKP matrix, enabling a dual-enhancement mechanism. The optimal formulation, containing 15 wt.% CSWs, boosts the 28-day compressive strength by 35% and the bond strength by 39%. Electrochemical analysis shows a 93.6% increase in coating resistance (Rf), indicating an improved physical barrier against corrosive species, along with a 52% reduction in corrosion current density. These improvements result from fiber bridging and a dissolution-reprecipitation process that densifies the whisker-matrix interface. Nevertheless, an excessive amount of CSW (20 wt.%) disrupts the matrix continuity and reduces performance. This work presents a high-strength, zero-VOC, spray-applied coating with a novel dual-enhancement mechanism for durable steel protection in aggressive environments.

Correlated electron systems with topological flat bands show great promise in exploring exotic quantum phenomena. However, such crystalline materials remain rare. Here we report the discovery of a novel material, Cs_3V_9Te_13, which unexpectedly exhibits magnetism and significant electron correlations. The crystal structure features two interpenetrating sets of vanadium triangles that can be linked with an ideal kagome lattice. The physical property measurements demonstrate a cascade of correlated electron phenomena, including quasi-two-dimensional bad metal, non-Fermi-liquid behavior, antiferromagnetic spin-density-wave transition at T_N = 47 K, possible short-range spin ordering at ∼350 K, a large Sommerfeld coefficient of 246 mJ mol-fu^-1 K^-2, and pressure-induced quantum criticality. These correlated electron behaviors are associated with the topological flat bands at the Fermi level, the latter of which are generated from the V2 sublattice in terms of a bipartite kagome model. Our findings establish Cs_3V_9Te_13 as a brand new correlated matter that synergistically combines flat-band physics and tunable properties.

NdFeAsO, a typical 1111-type iron-based superconductor (IBS), has a layered crystal structure consisting of alternating charge-reservoir Nd2O2 layers and conducting Fe2As2 layers, offering substantial potential for carrier doping. In this study, uranium (U) was incorporated into the Nd site, and a series of Nd1-xUxFeAsO samples were successfully synthesized. Rietveld refinement of X-ray diffraction (XRD) patterns revealed a systematic lattice contraction with increasing U content. Consistently, X-ray photoelectron spectroscopy (XPS) directly confirmed the substitution of U4+ for Nd3+ and the electron-doping nature of this substitution. Electrical transport measurements demonstrated that U doping effectively suppresses the spin-density wave (SDW) transition of the parent compound at ∼150 K and induces bulk superconductivity in the doping range 0.15 ≤ x ≤ 0.25. The optimally doped sample (x = 0.25) exhibits a high superconducting critical temperature (Tc) of 47.5 K, and its superconducting onset transition is markedly insensitive to the applied magnetic field, suggesting the presence of a high upper critical field (Hc2). This work demonstrates that U doping offers an alternative route for achieving superconductivity in the 1111-family IBS.

Kagome metals are prone to charge-density wave (CDW), magnetic, and superconducting phases, with their flat electronic band conducive for correlated physics. In contrast to the weakly correlated AV_3Sb_5 (A = K, Rb, Cs) kagome metals with a 2×2 CDW, CsCr_3Sb_5 is a correlated metal with a flat band close to the Fermi level, and exhibits a 4×1 CDW intertwined with magnetic order. Under pressure, the intertwined orders are suppressed and give way to a dome of superconductivity that emerges from a non-Fermi liquid normal state. Here, we solve the crystal structure of the 4× 1 CDW state in CsCr_3Sb_5, and show it consists of Cr dimers separated by Cr chains. First-principles calculations show the dominant exchange interaction is antiferromagnetic within the dimers, while the intra-chain and dimer-chain couplings are much weaker. The CDW transition of CsCr_3Sb_5 is found to be more strongly first-order than those in AV_3Sb_5, without significant soft phonons or diffuse scattering above the CDW transition temperature. These findings suggest that fluctuating antiferromagnetic dimers may play a major role in the electron pairing of superconducting CsCr_3Sb_5.

Transition-metal sulfide-based electrocatalysts hold great promise for the advancement of various renewable energy technologies, yet their complex in situ surface reconstruction during electrochemical operation remains a significant challenge. Herein, we report a highly efficient binder-free bifunctional electrocatalyst, FeS/CoS1.097@NC, consisting of cobalt-iron sulfide polyhedra encapsulated within nitrogen-doped carbon nanorods directly grown on carbon cloth. The judiciously designed FeS/CoS1.097@NC architecture features abundant active sites, moderate wettability, and reinforced electronic synergy, which collectively facilitate interfacial charge transfer and redox kinetics. As a bifunctional catalyst, FeS/CoS1.097@NC realizes a low overall overpotential of 0.6 V, comparable to that of the Pt/C+RuO2 benchmark. Combined experimental and theoretical investigation unravels that the in situ electrochemical reconstruction process promotes the formation and stabilization of Co-Fe (oxy)hydroxides as the dominant active phase. Notably, the reconstructed hybrid phases effectively modulate the d-band center and optimize the binding affinity of active sites toward (oxy) intermediates, thereby enhancing both oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) kinetics and long-term durability. When employed as a free-standing air-cathode, FeS/CoS1.097@NC endows rechargeable and flexible Zn-air batteries with high discharge capacities, superb rate capability and robust operational durability upon cycling. This work envisions a promising approach to constructing high-efficiency hetero-structured electrocatalysts toward multifunctional catalysis and portable/wearable energy devices.

We report the discovery of bulk superconductivity in a new quinary intermetallic compound Th 2 Mo 2 Ru 2 Si 4 C, which crystallizes in a collapsed 22241-type structure. This structure is characterized as an intergrowth of ThMo 2 Si 2 C and ThRu 2 Si 2 units, interconnected by equivalent Si-Si bondings that enhance inter-sublattice coupling. The refined lattice parameters are a = 4.2212(1) Å and c = 20.3899(7) Å. Electrical resistivity and magnetic susceptibility measurements on both polycrystalline and single-crystal samples consistently demonstrate bulk superconductivity with a transition temperature T c ~6.0 K, significantly higher than those of the constituent compound ThMo 2 Si 2 C and related analogs. The superconducting state exhibits nearly isotropic behavior under magnetic fields, attributable to strong covalent interlayer coupling. First-principles calculations reveal a substantial contribution from Mo- d orbitals near the Fermi level, which exhibits several band crossing points. The enhancement in T c can be explained by a synergistic combination of a valence electron concentration and an inter-sublattice self-doping effect between the [Ru 2 Si 2 ] and [Mo 2 Si 2 C] layers.

Abstract The decoupling of electrical and thermal transport parameters remains a central challenge in designing high-efficiency thermoelectric materials. While band structure engineering strategies such as band convergence have successfully guided the synthesis of high-performance alloys, direct spectroscopic validation of these mechanisms in simple binary compounds remains rare. Here we report an angle-resolved photoemission spectroscopy investigation of the layered semiconductor tin disulfide (SnS 2 ), a material theoretically predicted to possess outstanding thermoelectric properties. We unveil a valence band topology that serves as a realization of a desirable thermoelectric electronic structure. We observe a multi-valley valence band structure characterized by the simultaneous convergence of nearly degenerate maxima along the Γ-M and Γ-K high-symmetry directions. These topmost valence bands exhibit a remarkably flat dispersion near the extrema, indicating a large effective mass and a consequently high density of states. Furthermore, photon-energy-dependent measurements reveal a dimensionality decoupling where the electronic states maintain a two-dimensional confinement along the stacking axis despite the three-dimensional structural coherence of the crystal. This quasi-two-dimensional energetic nature prevents the dilution of the density of states, while the weak interlayer van der Waals interactions restrict the cross-plane thermal transport. These combined features effectively decouple electrical and thermal transport. Our findings provide the spectroscopic evidence for the giant thermoelectric potential of SnS 2 .

Ternary tellurides offer a rich platform for exploring exotic transport phenomena in low-dimensional quantum materials. Here, we report the observation of Dirac fermions, nontrivial surface states, and weak antilocalization in the layered telluride . First-principles calculations, complemented by angle-resolved photoemission spectroscopy (ARPES) measurements, reveal a series of robust Dirac points and nontrivial topological surface states near the Fermi level. The direct observation of linear band dispersions and surface-originated features provides clear evidence for its Dirac semimetallic nature. Transport measurements show a metallic behavior with a low-temperature resistivity upturn below 11.8 K, attributed to the combined effect of electron-electron interaction and weak antilocalization. The latter is further evidenced by a dip-like feature in the low-field magnetoresistance and the agreement with the Hikami-Larkin-Nagaoka quantum correction model. Hall measurements indicate dominant hole-type conduction. The resistivity upturn is enhanced under magnetic field or hydrostatic pressure, revealing tunable quantum transport. These findings suggest that is a promising material for exploring correlated topological phases and pressure-tunable quantum transport.

Metal-to-insulator transitions (MITs), particularly near room temperature, have been extensively studied in nonmagnetic and conventional ferromagnetic and antiferromagnetic systems, yet the co-emergence of MIT and altermagnetism (AM) remains unexplored. Here, a layered chromium-based compound CsCr_2S_2O that realizes this coexistence was synthesized. It crystalizes in CeCr_2Si_2C-type structure with Cr moments orders in a C-type antiferromagnetic configuration below T_N = 326 K, constituting a room-temperature d-wave altermagnet. In the altermagnetic state, a subsequent Verwey-type MIT appears at T_MI = 305 K, driven by a tetragonal-to-orthorhombic structural distortion and stripe charge ordering of Cr^+2/Cr^+3 ions, while maintaining its altermagnetic character. First-principles calculations show moment-dependent spin-split electronic structures with maximum splitting energies of 0.6 eV and 0.3 eV in the metallic and insulating states, respectively. Our work links the two prominent phenomena, MIT and AM, in a single material, establishing a new platform for potential spintronic applications.

Electrocatalytic water splitting using renewable electricity is widely regarded as a promising route to sustainable hydrogen production. However, its practical application is hindered by the sluggish kinetics of both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). A critical challenge remains: the lack of electrocatalysts that simultaneously achieve high intrinsic activity, long-term durability, and industrially relevant efficiency. Despite advances in catalyst design, current studies are still dominated by static descriptors and single-dimensional optimization, which fail to address the mismatch between material-level activity and device-level performance. In this review, we propose a six-dimensional coupled design framework for water electrolysis electrocatalysts. Specifically, electronic structure regulation (E), atomic-level active site definition (A), bulk-phase framework engineering (B), interfacial coupling (I), hierarchical architecture design (H), and dynamic evolution (D) are discussed as six mutually constraining dimensions. Altogether, these dimensions cover a hierarchical range, extending from microscopic electronic states at the atomic scale to the operational behavior of macroscopic devices. We first introduce the fundamentals of water electrolysis, including HER/OER mechanisms, thermodynamic and kinetic constraints, and evaluation metrics from intrinsic activity to industrially relevant performance. Subsequently, representative catalyst systems and design strategies are systematically discussed within the E-A-B-I-H-D framework, emphasizing structure-activity relationships and cross-dimensional interconnections. Finally, the key challenges and future directions toward predictive, multidimensional, and industrially relevant catalyst design are highlighted. This review aims to provide an integrative multiscale framework and practical design guidelines for developing high-performance electrocatalysts that bridge fundamental research and industrial water electrolysis.

Research on geopolymer-based ionic thermoelectrics has mainly focused on electrolytes while overlooking electrodes. Here, ionic transport blocking and reconstruction experiments show that bulk ions migration dominates the thermoelectric effect, with interfaces regulating this process. By introducing metallic and non-metal modified electrodes, we reveal electrode-dependent responses: Pt-geopolymer composite achieves the highest Seebeck coefficient (2.01 mV/K), whereas Ag-geopolymer composite exhibits polarity reversal. Mechanistic analysis indicates that interfacial microlayers of water act as gateways for ions entry and exit under a temperature gradient, with ion distribution and exchange governed by the electrochemical activity of the electrodes and their energy-level matching with the geopolymer. Specifically, well-matched, high-activity electrodes stabilize Na+ at the cold side and OH- at the hot side, enhancing the Seebeck effect, while poorly matched, low-activity electrodes cause polarization instability and response degradation.

The rapid growth of distributed and renewable energy systems has created an urgent demand for structural materials capable of simultaneously providing mechanical support and energy-storage functionality. Conventional cementitious materials, however, exhibit low ionic conductivity and poor electrochemical activity, limiting their use in multifunctional energy-storage structures. To address this challenge, this study explores the development of alkali-activated metakaolin (MK) geopolymers modified with different sodium salts (Na2SO4, NaCl, and NaOH) as structural solid electrolytes. The incorporation of sodium salts enhanced the ionic conductivity and capacitive behavior of the MK-based electrolytes. Results showed that the incorporation of sodium salts significantly enhanced the ionic conductivity and capacitive performance of the geopolymer electrolytes. The Na2SO4-modified sample (MK-S) exhibited the highest ionic conductivity of 33.22 mS cm-1 and an areal capacitance of 603.93 mF cm-2, corresponding to a 4.5-fold increase over unmodified MK. This improvement is primarily associated with enhanced Na + availability and refined pore connectivity attributed to the presence of SO42-anions. These findings demonstrate a viable route toward structural electrolytes for next-generation energy-storage-integrated building materials, although further investigation under application scenarios is still required.

Abstract We report the pressure effect on the MnP-layer-based material, RbTh 2 Mn 4 P 4 N 2 , which is a self-doped correlated antiferromagnetic bad metal at ambient pressure. Measurements of the temperature- and pressure-dependent electrical resistivity [ ρ ( T , P )] were performed at temperatures down to 0.4 K and under high pressures up to 38.2 GPa. At 12 GPa, an anomaly at ~240 K is observed, which is attributed to the suppressed antiferromagnetic transition. This ρ ( T ) anomaly changes abruptly into a broad hump at 13 GPa, signaling short-range magnetic ordering. Above 16.9 GPa, the ρ ( T ) hump disappears and the system evolves into a high-pressure metallic state exhibiting non-Fermi-liquid behavior. The first-principles calculations suggest that the high-pressure phase has a collapsed structure in which magnetic quantum criticality may emerge due to exchange-interaction frustrations.

Insufficient interfacial interaction between nanoconductive materials and polymer matrices severely limits the mechanical, electrical, and pressure-sensing properties. Carbon nanotubes (CNTs), widely used as polymer reinforcements due to their excellent properties, can significantly enhance the mechanical performance of nanocomposites by improving the interfacial interactions with the matrix. Given the diversity of functionalized CNTs, a systematic study of their interfacial bonding mechanisms is of great importance for both scientific research and engineering applications. To this end, this study employs molecular dynamics simulations to investigate the interfacial characteristics and mechanical responses of functionalized CNT/polyimide (PI) systems. The results demonstrate that functionalization treatments significantly enhance both the interfacial interaction and the shear performance of CNT/PI nanocomposites. Specifically, the interfacial shear strength of the carboxylated CNT/PI composite reaches 269.83 MPa, representing a 20% improvement; furthermore, this property further increases with higher functional group content. This work elucidates the influence of functional group type and content on the interfacial shear performance of CNT/PI composites at the atomic scale, providing new physical insights.