Designing differentiated charge distributed interface has been considered as effective strategy to boost photocatalysis. However, it is still difficult to realize the directional strong polarization to continuous drive directional charge transfer. Here, we present a polarization state reinforcement strategy by coupling Bi19S27Cl3 with covalent triazine framework (CTF) atomic layers via strong bonding. The intrinsic Bi1 & horbar;S & horbar;Bi2 polarize site pair in Bi19S27Cl3 enables rapid bulk charge transport, while interfacial Bi & horbar;C/N bond further strengthens the Bi1 & horbar;S & horbar;Bi2 polarization and favors fast interfacial electron transfer from Bi19S27Cl3 to CTF. Then, the electron-rich triazine N in CTF will serve as reactive sites to reduce the adsorbed NO3 - to NH4 +, with NH4 + generation rate of 13.65 mmol g-1 h-1 in 320-780 nm, and apparent quantum yield up to 46.7% at 380 nm, 30.5% at 400 nm, which is superior to most reported photocatalyst. Moreover, the gradual shift from non-covalent interactions of *NO over CTF to covalent interactions over CTF/Bi19S27Cl3 can help to stabilize the intermediate and lower the rate-limiting step energy barrier.

Solar-driven selective synthesis of C2 chemicals from CO2 is a crucial pathway for carbon cycling, but it is limited by the high kinetic barrier of C─C coupling. This study proposes an epitaxial growth strategy for lattice-bonded asymmetric sites. By constructing a Bi1─O─Bi2 site at the Bi3NbO7 nano-dots/Bi3O4Br nanosheet (BNO/BOB) interface to promote C─C coupling for acetic acid production, the photocatalytic conversion rate of CO2 to acetic acid can reach 192.3 µmol·g-1·h-1, with 91.4% selectivity. The apparent quantum efficiency at 380 and 400 nm reach 9.49% and 6.57%, respectively. The key mechanism originates from a cascade electron effect triggered by the interfacial Bi1─O─Bi2 sites: the interfacial charge redistribution induces a strong built-in electric field, where high-energy electrons selectively occupy the 2π antibonding orbitals of CO* intermediates, significantly weakening the C─O bond in CO* intermediate. Furthermore, the asymmetric charge redistribution effectively neutralizes the electrostatic repulsion between adjacent CO* intermediates, synergistically stabilizing the OCCO* transition state through d-π electron feedback from Bi sites. The dual effects synergistically lower the energy barriers for both the C─C coupling and hydrogenation steps, ultimately steering the reaction pathway towards long-lasting acetic acid formation.

Solar-driven conversion of CO2 and biomass-derived alcohols offers a promising strategy for mitigating CO2 emissions and providing value-added chemicals. However, due to complex reaction pathways and sluggish C-H bond activation, it remains challenging to attain efficient photocatalytic CO2 reduction to CH4 alongside the valorization of biomass-derived alcohols. Herein, we report a judicious design to construct asymmetric dual-metal catalytic centers via anchoring semiconductor nanoclusters in vacancy-rich MOFs, achieving tandem CO2-to-CH4 photoreduction with C-H oxidation. Through loading Fe2O3 clusters in O-vacancy-rich Mil-125(Ti)-NH2, interfacial O-vacancy renders a newly formed Fe-O bond as an atomic-level electron transfer pathway toward Z-scheme construction. Furthermore, the interfacial vacancies trigger intimate interactions and modulate the d-band center to form asymmetric Ti-Fe dual-metal sites. Remarkably, a superior selectivity of 87.0% toward CH4 production coupled with 100% selectivity for benzyl alcohol-to-benzaldehyde oxidation is realized. Mechanistic investigations reveal that the heteronuclear Ti-Fe units synergistically facilitate the hydrogenation of *CO to *CHO through d-p hybridization, thereby enabling CH4 synthesis to be thermodynamically favorable, while photogenerated holes from Fe2O3 preferentially oxidize the α-C-H bond of benzyl alcohol. Further supported via another MOFs-based catalyst, this work enlightens a general design of building asymmetric dual-metal interfaces to concurrently realize selective CO2 photomethanation coupled with C-H activation.

The Group-VI transition metal ditellurides offer a rich platform for correlated and topological phenomena, yet their structural polymorphism and instability complicate the creation of single crystals and heterointerfaces. Here, we introduce a confined-space chemical vapor deposition (CVD) strategy that lowers the growth temperature window and, when combined with tailored precursor configurations and stepwise thermal ramps, enables the deterministic synthesis of high-quality single crystals, alloys, and lateral/vertical heterostructures. High-resolution aberration-corrected STEM provides atomic characterization of lattice-matched Mo(W)Te2 lateral heterostructure, revealing nearly atomically sharp, compositionally well-defined seamless boundaries. This approach avoids the thickness nonuniformity and structural limitations commonly associated with exfoliated samples, enabling reproducible fabrication of clean heterointerfaces and establishing a nearly ideal in-situ experimental system. Furthermore, scanning tunneling microscopy and spectroscopy (STM and STS) enable direct imaging of the seamless boundaries in Mo(W)Te2 lateral heterostructures, while uncovering their distinct real-space distributions of the local density of states. Our results establish a scalable pathway for engineering crystalline Te-based structures with controlled geometry and stacking, providing an essential step toward quantum and topological device platforms based on the transition metal ditellurides family.

Various catalysts have been applied to improve the sensing performance of metal oxide semiconductor (MOS) gas sensors, but achieving high response and outstanding selectivity at low working temperature remains an extremely tough challenge for traditional chemiresistive gas sensors (CGSs). Herein, an in-situ annealing approach has been developed to synthesize composite material with Pt single atoms (Pt SAs) anchored on In2O3 substrate for highly sensitive and selective detecting isoprene at low concentrations (50 ppb) under low temperature of 70 degrees C. Besides, pure In2O3 and Pt nanoparticles (Pt NPs) were utilized as comparisons to further investigate enhanced sensing mechanism with the support of Pt SAs. Experimental and response kinetic model results suggested that Pt SAs can not only serve as active sites to promote the oxidation of isoprene, but also act independently as binding sites to facilitate the adsorption of isoprene on In2O3 surface. Simultaneously, density functional theory (DFT) calculations demonstrate that Pt SA provides a selective adsorption site for isoprene over other gases, thereby facilitating targeted adsorption of isoprene on In2O3 nanoclusters. This study proves the successful anchoring of Pt SAs on In2O3 nanoclusters by utilizing atomic-level interface modulation engineering strategy, providing an attractive strategy for developing CGSs with high response and selectivity at low working temperatures.

A central challenge in single-atom catalysis lies in the precise construction of structurally well-defined local coordination environments at isolated metal sites while retaining low coordination numbers. Here, we present an edge-bonding strategy that confines isolated metal atoms to well-defined edge sites of covalent triazine frameworks, enabling deterministic construction of structurally defined low-coordination environments. With Ni as a model, this approach yields single-atom sites with a well-defined Ni-N1-C6 coordination motif and allows precise control over their spatial distribution. The strategy is readily extendable to other metals, affording single-atom catalysts with structurally defined and highly accessible low-coordination environments. Such geometrically low-coordination sites optimize photogenerated carrier separation and transport while selectively stabilizing the key *OCHO intermediate in the CO2 reduction pathway, thereby directing the reaction toward HCOOH with 98.5% selectivity. This work establishes a principle for achieving low-coordination microenvironments at single-atom sites via macroscopic regulation of support structures, providing a rational strategy for single-atom catalyst design.

Mott insulators are a unique class of materials whose insulating state originates from strong electron-electron correlations: the interactions localize charge carriers, and the resulting on-site Coulomb repulsion opens a charge gap, fundamentally different from conventional insulators, making these systems an exceptional platform for exploring exotic physical phenomena. Significantly, the interplay between strong correlations and charge transfer not only stabilizes the antiferromagnetic ground state but also endows the material with enriched properties, particularly in optics. Herein, we demonstrate a 2D antiferromagnetic charge-transfer Mott insulator, Vanadium Oxychloride (VOCl), which shows giant third-harmonic generation (THG) anisotropy (ρTHG = Ix/Iy, where Ix and Iy represent the THG intensities corresponding to the excitation polarization parallel to crystal’s x- and y-axes), with ρTHG reaching up to 187 at 1280 nm excitation wavelength. Notably, it is the highest THG anisotropic ratio within the van der Waals materials family. The nonlinear anisotropy is further modulated across a broadband infrared (IR) excitation wavelength range from 2028 to 1280 nm, during which ρTHG rises from 2.6 to 187, corresponding to a 72-fold enhancement relative to its value at 2028 nm. Additionally, VOCl demonstrates layer-independent third-order susceptibilities (χ(3) ~ 10-19 m2/V2) and band structures attributed to its extremely weak interlayer electronic coupling. Moreover, the colossal THG anisotropic ratio in 2D VOCl can be ascribed to the synergistic effect of the correlated charge-transfer Mott insulator behavior and intrinsic C3 symmetry breaking, as supported by theoretical calculations. The colossal nonlinear optical anisotropy in 2D VOCl positions it as an excellent candidate for nanophotonic and optoelectronic applications, enabling next-generation nanodevices based on 2D correlated Mott insulators. Giant THG anisotropy in 2D VOCl emerges from a synergistic coupling of charge-transfer Mott insulator behavior with intrinsic C3 symmetry breaking.

Nonlinear frequency upconversion of mid-infrared (MIR) light is of particular importance for infrared imaging, detection and spectroscopy. However, achieving efficient and broadband MIR upconversion is hindered by phase-matching constraints and limited nonlinear coefficients of optical materials. Here, we demonstrate phase-matching-free, broadband and efficient multiphoton frequency upconversion in NbOI2. We observe generation of harmonics from the second to the 11th order, with upconverted signals spanning from the MIR to the ultraviolet. We also achieve nonlinear frequency mixing in the broad spectral window of 1500-5000 nm, including degenerate four-wave mixing, sum-frequency mixing and sum-frequency generation with an efficiency up to 6×10-⁴ W-¹, surpassing those of leading metasurface-based platforms. Finally, we demonstrate broadband MIR upconversion imaging by direct detection from a conventional silicon camera. Our results establish NbOI2 as a promising platform for MIR nanophotonics, enabling advanced applications in ultrabroadband imaging, sensing and spectral conversion.

Taking advantage of the phase transition characteristics of VO2, we designed and experimentally verified a 0.1 THz tunable metalens. This 24-mm-aperture metalens based on geometric phase can achieve transmission or reflection focusing as designed. It was fabricated at low cost by 3D printing of Al2O3 combined with magnetron sputtering of VO2. The measured focal length and full-width-at-half-maximum are in agreement with the simulation, providing a feasible solution for THz reconfigurable optics.

A central challenge in single-atom catalysis lies in the precise construction of structurally well-defined local coordination environments at isolated metal sites while retaining low coordination numbers. Here, we present an edge-bonding strategy that confines isolated metal atoms to well-defined edge sites of covalent triazine frameworks, enabling deterministic construction of structurally defined low-coordination environments. With Ni as a model, this approach yields single-atom sites with a well-defined Ni-N1-C6 coordination motif and allows precise control over their spatial distribution. The strategy is readily extendable to other metals, affording single-atom catalysts with structurally defined and highly accessible low-coordination environments. Such geometrically low-coordination sites optimize photogenerated carrier separation and transport while selectively stabilizing the key *OCHO intermediate in the CO2 reduction pathway, thereby directing the reaction toward HCOOH with 98.5% selectivity. This work establishes a principle for achieving low-coordination microenvironments at single-atom sites via macroscopic regulation of support structures, providing a rational strategy for single-atom catalyst design.

Capturing the dynamic behavior of heterogeneous catalysts under realistic reaction environments is essential for understanding their structure-property relationships and advancing catalyst design. Although conventional silicon nitride-based gas cells allow atomic-resolution imaging at ambient pressure, the 30-50 nm windows on each side make images appear "foggy", hindering reliable detection of single-atom species and complicating chemical analysis. Here, we present a graphene-based gas cell by integrating mechanically exfoliated multilayer graphene (e.g., 1-3 nm) onto micropatterned MEMS chips, offering greatly reduced adverse diffuse-scattering background together with excellent gas tightness, which could maintain gas tightness at at least 101.3 kPa (1 atm) pressure and operational stability at temperature as high as 800 °C. This graphene gas cell effectively "lifts the fog" for in situ electron microscopy at high gas pressure, demonstrating robust single-atom sensitivity with both high (e.g., 200 keV) and low (e.g., 80 keV) energy electrons. It also enabled significantly improved signal-to-background ratios in electron energy loss spectroscopy (EELS) analysis under a gaseous environment. This ultrathin, robust graphene gas cell architecture opens opportunities for better probing of gas-solid interactions with robust single-atom sensitivity and atomic resolution.

The role of vacancy associates for photocatalysis is still an open question. Here, the CuIn2S4 atomic layers with Cu-S vacancy associates is developed to study the influence of vacancy associates on photocatalytic nitrate-ammonia conversion. The engineered Cu-S vacancy associates improve the light absorption intensity of CuIn2S4 among the infrared region. Meantime, it can create a symmetry-breaking structure in CuIn2S4, resulting in differentiated charge-redistributed surface atomic structure and forming local polarization center. This distinctive configuration enables the formation of charge density gradient, favors directional charge transfer and NO3- polarization, contributing to excellent photocatalytic ammonia synthesis performance. The NH3 generation rate over VCu-S rich CuIn2S4 via NO3- reduction arrives 975.9 and 583.9 mu mol g(-1) h(-1) under UV-Vis and NIR light irradiation, with apparent quantum efficiency of 15.87 %, 11.2 %, 7.83 %, 7.12 %, 5.33 %, 4.15 %, 3.62 %, 0.93 %, 0.54 %, 0.34 % at 380, 400, 450, 500, 550, 650, 700, 800, 850, 1064 nm, respectively. The construction of Cu-S vacancy associates with asymmetric charge distributions enhances the non-covalent interactions with reaction intermediates and effectively lower the energy barrier of rate-determining step. This work supplies fresh insights into the important role of Cu-S vacancy associates in photocatalytic ammonia synthesis.

Building differentiated charge distributed polarized atomic pairs may be an alternative for N2 activation. In this work, CuInS2 atomic layers with asymmetric In-In polarized site pairs are prepared by doping Fe single atoms, as proved by X-ray absorption fine structure spectroscopy, quasi in situ X-ray photoelectron spectra and calculated atomic charge distribution. The engineered Fe single atoms tuned the surface atomic charge distribution, building local polarization center to boost directional surface charge separation. The formed In-In polarized site pairs with asymmetric charge distribution creates distinct interaction with two N atoms in N2 molecule, contributing to the enhanced activation of N2. The alternating pathway is regarded as hydrogenation pathway over Fe-CuInS2 with *NNH formation as rate-determining step. The charge-redistributed surface atomic structure after engineered Fe single atoms strengthens intermediate interaction and lower the rate-determining step energy barrier. Benefiting from these features, Fe-CuInS2 exhibits excellent photocatalytic activity under near-infrared (NIR) irradiation with an ammonia synthesis rate of 94.1 lmol g-1 h-1. In comparison, the N2-NH3 conversion rate of Fe-CuInS2 under ultraviolet-visible (UV-Vis) irradiation could reach 137.4 lmol g-1 h-1, which is about 6.8 times higher than that of CuInS2. The apparent quantum efficiencies of Fe-CuInS2-2 at 380, 400, 450, 500, 550, 650, 700, 800, 850 and 1064 nm were 3.0 %, 3.3 %, 2.7 %, 2.1 %, 2.0 %, 1.5 %, 1.3 %, 0.4 %, 0.7 % and 0.6 %, respectively.

Chromium tellurides represent a novel class of two-dimensional ferromagnets with significant potential for advanced electronic applications, including spintronics and magnonics. Despite their promise, the fabrication of large-area samples remains a considerable challenge. In this study, we report a facile modification to the common ambient-pressure chemical vapor deposition setup that enables the synthesis of ultrathin Cr3Te4 nanosheets (6.4 nm thick) with lateral dimensions exceeding 100 mu m. Our findings reveal that by tuning both the growth temperature and the distance between the precursor and substrate, the size and morphology of the synthesized CrxTey nanosheets were significantly impacted. The resulting large-size Cr3Te4, synthesized under 800 degrees C, exhibits robust ferromagnetism, with a Curie temperature reaching 178 K. This advancement in the preparation of large-area Cr3Te4 nanosheets opens new avenues for their integration into next-generation electronic devices.

Precisely designing the atomic coordinate configuration of the reactive center is highly desired to lower the energy barrier and boost photocatalytic ammonia synthesis performance. Here, we describe the isolated asymmetric Fe delta+-O-Bi (2

Oxide interfaces have enormous potential for future electronics with many applications, such as large spin Hall conductance, phase transitions, topological states, and superconductivity. However, previous investigations have predominantly focused on gigahertz frequencies; whilst the possibilities to fabricate devices operational at terahertz frequencies are demonstrated. A model solution is proposed employing 5d rare-earth, strontium iridate (SrIrO3) heterostructure with cobalt (Co) ultrathin layers. Femtosecond lasers are used to photoexcite the spins in Co, which super diffuse into the SrIrO3 layer to produce an ultrafast inverse spin Hall effect in sub-picosecond timescales. The devices exploit the external magnetic field and laser fluence to control the spin polarization from the Co layer and demonstrate a tailored spin Hall effect. These results thus pave paths for next-generation ultrafast oxide electronics offering possibilities for room temperature-based devices.

Two-dimensional (2D) PdSe2 atomic crystals hold great potential for optoelectronic applications due to their bipolar electrical characteristics, tunable bandgap, high electron mobility, and exceptional air stability. Nevertheless, the scalable synthesis of large-area, high-quality 2D PdSe2 crystals using chemical vapor deposition (CVD) remains a significant challenge. Here, we present a self-limiting liquid-phase edge-epitaxy (SLE) low-temperature growth method to achieve high-quality, centimeter-sized PdSe2 films with single-crystal domain areas exceeding 30 mu m. The SLE growth mechanism, clarified by theoretical calculations and time-of-flight secondary ion mass spectrometry (ToF-SIMS), reveals that hydrogen ions on the precursor surface inhibit vertical growth while promoting lateral growth. The as-grown PdSe2 few-layer exhibits a surface roughness of 1.20 nm and an average conductivity of 1.67 x 10-6 S/m, demonstrating their smoothness and uniformity. Temperature-dependent electrical measurements and transfer characteristic curves confirm the orthorhombic PdSe2's bipolar semiconductor behavior. The photodetector based on few-layer PdSe2 films exhibit excellent optoelectronic performance in the 405-1650 nm wavelength range, achieving a responsivity of 6262.37 A W-1, a detectivity of similar to 1012 Jones under 1064 nm illumination, and a fast response time of 37.1 mu s, making them highly suitable for broadband photodetection applications. This work provides valuable insights into the scalable synthesis of PdSe2 few-layers and establishes a foundation for the development of PdSe2-based integrated functional devices.

The scaling relationship among reaction intermediates with strongly correlated adsorption energy in the oxygen evolution reaction (OER) severely restricts the energy-conversion efficiency of water electrolysis. For the conventional adsorbate evolution mechanism, breaking the scaling relationship remains challenging, as it is difficult to modulate the adsorption of multiple intermediates on a specific active site simultaneously. Herein, we utilize the electron buffering effect of a two-dimensional fullerene network (C60NET) to dynamically tune the electronic structure of the iridium (Ir) active site with the change of adsorbed intermediates, which can tailor the adsorption strength of intermediates from multistep reactions and break the adsorption-energy scaling relationships among *OOH, *O, and *OH. The C60NET-buffered Ir nanocluster catalyst exhibits excellent OER activity with a low overpotential of 237 mV and stability over 600 h at 10 mA cm-2, outperforming graphene-supported Ir nanoclusters and commercial IrOx, attributed to the breaking of the linear scaling relationship enabled by the unique ability to reversibly accept and donate electrons of C60NET.

Effective photogenerated charge transfer and utilization have been regarded as a critical factor for achieving highly efficient photosynthesis of ammonia. However, the lacks necessary driving force in many catalysts limit the directly charge transfer. In this work, Cu porphyrin-based monoatomic layer (PML-Cu) is modified on face-centered cubic structured defective CdIn2S4 via solvothermal reaction, with a strong coupled interfacial Cu & horbar;S bond is constructed. Owing to the formation of axial CuS1N4 polarization site, the local interfacial asymmetric configuration can be created between CdIn2S4 and PML-Cu to form a strong potential difference, inducing the rapid charge transport from CdIn2S4 to PML-Cu via Cu & horbar;S bond. Meantime, the electron-enriched CuS1N4 site is beneficial to the stabilization of *NHOH intermediate state, and then lowering the *NHO ->*NHOH rate-limiting step energy barrier. Benefiting from these features, the PML-Cu/CdIn2S4 exhibit good NH3 generation rate of 1979.0 mu mol g(-1) h(-1), with apparent quantum efficiency of 8.56% at 380 nm and 7.40% at 450 nm, respectively. This work provides an accessible pathway for designing interfacial asymmetric configuration with strong coupling to boost photocatalysis.