SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4476-1
Self-sustained oscillation in soft actuators enables autonomous, untethered robotic locomotion, yet existing light-driven systems suffer from low oscillation frequencies, rapid photothermal degradation, and reliance on external controllers. This work presents a bat-inspired soft robot that converts continuous near-infrared (NIR) irradiation into sustained rotational motion via a coiled MXene-based liquid crystal elastomer (LCE) actuator. The actuator integrates Ti3C2Tx MXene nanosheets as photothermal converters within an LCE matrix, achieving a photothermal conversion efficiency of 78.3% and a steady-state temperature of 142 °C under 1.5 W cm−2 NIR (808 nm). The coil geometry induces a self-shadowing effect that generates periodic light exposure, producing autonomous oscillation at 2.7 Hz with an amplitude of 45°. The robot demonstrates a rotational speed of 120 rpm and a specific power density of 3.2 W kg−1, outperforming previously reported light-driven oscillators by a factor of 2.5. Under continuous operation for 10,000 cycles, the actuator retains 92% of its initial oscillation amplitude, with a degradation rate of 0.008% per cycle. The bat-inspired wing morphology enables directional rotation and obstacle avoidance in confined spaces. This platform eliminates the need for external modulation, offering a scalable route to autonomous soft robotics for inspection, environmental monitoring, and micro-manipulation.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4373-2
Infrared stealth technology demands materials with simultaneously low infrared emissivity and robust environmental stability. Traditional coatings suffer from high emissivity or poor thermal stability. Here, we report Sr-doped SmCoO3 perovskite ceramics achieving a record-low room-temperature infrared emissivity of 0.12 in the 8–14 μm atmospheric window. Systematic doping (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) via solid-phase synthesis reveals that Sr substitution induces a Co3+/Co4+ mixed valence state, increases oxygen vacancy concentration, and distorts the lattice. First-principles calculations (CASTEP) confirm that doping narrows the bandgap from 1.8 eV to 0.9 eV and enhances the double-exchange interaction, boosting carrier concentration and mobility. The optimized composition (x = 0.3) exhibits an electrical conductivity of 1.2×10^3 S/cm and a carrier density of 3.5×10^21 cm^-3, leading to strong infrared reflection. The material maintains emissivity below 0.15 after 100 hours of thermal cycling at 300°C and 500 hours of humidity exposure (85°C/85% RH), demonstrating exceptional environmental durability. This work establishes a new paradigm for designing high-performance inorganic infrared stealth materials via electronic-structural synergy.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4381-5
Bismuth telluride (Bi2Te3)-based alloys remain the benchmark for low-temperature thermoelectric applications, yet their conversion efficiency is limited by the trade-off between electrical and thermal transport. This study introduces a pseudo grain boundary engineering strategy to simultaneously enhance the average figure of merit (ZT) in p-type (Bi,Sb)2Te3 (BST) materials. By incorporating Ag-based compounds, the carrier concentration is optimized via substitution of Ag+ ions, while the introduction of secondary phases at grain boundaries effectively suppresses lattice thermal conductivity. The approach yields a peak ZT of 1.35 at 393 K and an average ZT of 1.25 across 303–483 K, representing a significant improvement over pristine BST. Compared to prior reports, this work achieves superior average ZT while maintaining high electrical conductivity, addressing the longstanding bottleneck of thermal conductivity reduction without compromising carrier mobility. The findings underscore the efficacy of pseudo grain boundary engineering in advancing Bi2Te3-based thermoelectrics for solid-state cooling and power generation.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4234-3
The pursuit of high-energy-density sodium-ion batteries (SIBs) necessitates the development of stable high-capacity anodes. While amorphous carbon is a promising anode candidate for SIBs, its practical application is hindered by limited capacity. Herein, we design a composite anode by chemically confining a high-content (~25 wt%) short-chain sulfur into hierarchical porous hard carbon microspheres (SHHC) derived from microbe yeast. The SHHC anode exhibits a high reversible capacity of ~807 mAh g−1 at 0.03 A g−1 (~3 times that of conventional amorphous carbon) along with superior rate capability, and extraordinary long-term cyclability (almost 100% capacity retention after 2000 cycles at 1.0 A g−1). The high-content sulfur species contribute to superb redox reactivity for high-capacity sodium storage via a surface-dominated storage mechanism. The carbon matrix features an enlarged interlayer distance, which facilitates Na-ion intercalation and deintercalation for high-rate capability. Furthermore, the hierarchical porous structure with built-in cavities facilitates the Na-ion transfer and effectively accommodates the electrode’s volume expansion, achieving fast electrode kinetics and outstanding cyclability. Such a combination of favored properties leads to state-of-the-art comprehensive battery performance for Na-ion storage. Our finding envisions a new perspective on building stable high-capacity anode materials for SIBs.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3848-7
Conventional heterogeneous photocatalysts often suffer from insufficient light absorption, rapid charge recombination, and a lack of specific reactive sites for efficient photocatalytic oxidation. To overcome these limitations, we propose a molecular polarization engineering approach utilizing structurally well-defined donor (D)-acceptor (A) covalent triazine frameworks (CTFs). The construction of dipole-induced built-in electric fields within the D-A-structured CTFs enables enhanced exciton dissociation and facilitates directional charge transfer. Specifically, the asymmetric A1-D-A2 moiety enhances molecular polarization in the dual-acceptor system CTF-TBT (A1-D-A2), enabling efficient charge separation through multiple electron-withdrawing units. This structural design promotes directional electron transfer toward the secondary acceptor (benzothiazole, A2), while simultaneously concentrating holes on the donor unit. Consequently, the A2 moiety acts as a site for efficient O2 activation via electron accumulation, whereas the highly oxidized donor unit provides strongly positive holes (h+) that facilitate substrate oxidation. Experimental and DFT calculation results confirm that CTF-TBT demonstrates highly enhanced photocatalytic oxidation performance, which can be attributed to its multi-channel charge separation mechanism and spatially separated redox-active sites. This study highlights the effectiveness of molecular dipole engineering in designing heterogeneous photocatalysts with controlled charge transfer pathways and improved redox capabilities. The proposed design principles provide a universal approach for promoting solar-driven chemical synthesis applications.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025121001
Ion chromatography (IC) is the core analytical method for qualitative and quantitative determination of anions in complex water environments, and its separation efficiency highly depends on the performance of the stationary phase. This review systematically summarizes recent progress in the preparation and functionalization of IC stationary phases, addressing the urgent need for high selectivity and sensitivity in water anion analysis. The characteristics of organic polymer-based and inorganic-based matrices are compared, highlighting the advantages of polymer matrices such as poly(methacrylate), poly(vinyl alcohol), polystyrene-divinylbenzene (PS-DVB), and ethylvinylbenzene-divinylbenzene (EVB-DVB) in terms of wide pH tolerance (e.g., pH 0–14 for PS-DVB) and organic solvent compatibility, which allow the use of strong acid or base eluents. Various functionalization strategies are discussed, including the introduction of quaternary ammonium groups, hydrophilic modifications, and grafting of functional layers, which enhance separation selectivity and detection capability. The review also covers the development of hybrid stationary phases and the application of IC in monitoring trace pollutants in water, such as bromate, chlorite, chlorate, fluoride, and nitrate, as regulated by Chinese standards (GB 5749—2022). Future trends are projected, focusing on novel materials for precise identification and high-throughput monitoring. The paper provides a comprehensive reference for the design of high-performance stationary phases, emphasizing the importance of matrix selection and surface chemistry in achieving robust and sensitive anion analysis.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202604009
Biological nitrogen removal in wastewater treatment plants (WWTPs) is often limited by insufficient influent carbon sources, necessitating external carbon addition to enhance denitrification. Conventional single carbon sources, such as sodium acetate, frequently fail to meet the metabolic demands of complex microbial communities, compromising nitrogen removal efficiency and stability. Composite carbon sources, by providing multiple electron donors, can improve metabolic cooperation among microorganisms, yet their underlying microbial mechanisms remain insufficiently understood. In this study, activated sludge from a municipal WWTP was used to investigate the microbial mechanisms of composite carbon sources during denitrification. Batch denitrification experiments were conducted in combination with metagenomic and metatranscriptomic analyses to systematically characterize microbial community structure and functional gene expression under different carbon source conditions. Results showed that, compared with sodium acetate as the single carbon source, the composite carbon source system (sodium acetate: sodium succinate: ethanol = 2:1:3) increased the denitrification rate from (6.822 ± 0.141) mg/(L·h) to (8.370 ± 0.186) mg/(L·h), representing a 22.7% improvement, while reducing N2O accumulation by approximately 55%. Metagenomic analysis revealed that Ottowia, Rubrivivax, Thauera, and Zoogloea were the dominant denitrifying genera. Metatranscriptomic results further demonstrated that the composite carbon sources significantly upregulated the transcription of key denitrification genes, with nirS, norB, and nosZ increasing by 37.8%, 27.4%, and 48.6%, respectively. In addition, the composite carbon sources promoted complementary carbon metabolic strategies among different microbial communities, enhancing electron donor supply and improving denitrification efficiency. These findings indicate that composite carbon sources synergistically enhance denitrification performance through regulation of functional gene transcription in complex microbial communities, providing a theoretical basis for carbon source optimization in WWTPs.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025102002
The ultraviolet/chlorine (UV/Cl2) advanced oxidation process generates multiple radical species, enabling synergistic disinfection. However, the systematic influence of UV intensity on process performance remains inadequately characterized. This study investigated UV intensities from 0.25 to 2.0 mW·cm−2, assessing chlorine photolysis kinetics, bacterial inactivation, and disinfection by-product (DBP) formation. Results demonstrate that inactivation efficiency is not solely governed by total UV energy but is co-regulated by reaction kinetics and mass transfer. Increasing UV intensity accelerated chlorine photolysis by 33.7%–277.8%, elevating steady-state concentrations of hydroxyl radicals and chlorine radicals by factors of 1.6–3.8 and 1.3–3.2, respectively, thereby enhancing initial inactivation rates. However, higher intensities reduced cumulative chlorine exposure (CT value) to 14.3%–55.7% of baseline, causing overall inactivation to first increase then decrease. At a fixed UV dose of 150 mJ·cm−2, an intensity of 1.0 mW·cm−2 achieved optimal 6.5-log inactivation of Escherichia coli and the lowest bacterial reactivation rate (0.07%). Common water constituents (HCO3−, Cl−, natural organic matter) inhibited disinfection, with natural organic matter exerting the strongest suppression (2.7-log reduction). Notably, 1.0 mW·cm−2 exhibited the greatest resistance to interference. Elevated intensity reduced total organic halogen formation from 33.7 μg·L−1 to 19.0 μg·L−1. Balancing disinfection efficacy and DBP risk, 1.0 mW·cm−2 is identified as the optimal UV intensity for the UV/Cl2 process in sand-filtered water treatment.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202509026
Rocky desertification poses a severe threat to ecosystem function in karst regions of southern China. This study, conducted in Jianghua Yao Autonomous County, Hunan Province, investigated the adaptive responses of Paulownia fortunei to rocky desertification habitats and its subsequent effects on soil properties. Leaf structural and physiological parameters were measured, alongside soil physicochemical properties. Results demonstrated that P. fortunei enhanced its adaptability through increased leaf thickness (upper epidermis +50%, total +27.38%), palisade tissue thickness (+22.45%), elevated chlorophyll a (+3.55 mg·g−1) and chlorophyll b (+1.39 mg·g−1) contents, and upregulated activities of superoxide dismutase, catalase, and peroxidase. Planting P. fortunei significantly improved soil structure and fertility: soil bulk density decreased by 0.57 g·cm−3, total porosity increased by 2.41% (0–5 cm) and 3.35% (5–10 cm), field water capacity rose by 18.63% and 18.87%, capillary porosity increased by 11.45% and 14.19%, and soil organic matter content improved from Grade IV to Grade II. These findings indicate a synergistic 'plant adaptation–soil improvement' feedback mechanism, highlighting the potential of P. fortunei for ecological restoration of rocky desertification areas.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025030403
Microplastics (MPs) act as vectors for co-migrating antibiotics and heavy metals, forming complex pollution systems with potential joint toxicity. However, the differential adsorption behaviors and underlying mechanisms of MPs toward organic versus inorganic pollutants remain insufficiently understood. This study selected polypropylene (PP) microplastics, a major component of agricultural plastic films, and investigated the adsorption of sulfamethoxazole (SMX) and Cr(VI) onto aged PP under varying environmental conditions. Results demonstrated that aging increased the maximum adsorption capacity by 2–3 times for both pollutants. Notably, aged PP exhibited approximately 30 times higher adsorption capacity for SMX than for Cr(VI). Characterization revealed that aging introduced oxygen-containing functional groups (e.g., carbonyl) on the MP surface, enhancing adsorption. Mechanistic analysis indicated that hydrogen bonding and electrostatic interactions dominated SMX adsorption, while Cr(VI) adsorption was primarily governed by electrostatic interactions and pore-filling. The stronger intermolecular forces for SMX compared to reversible pore-filling for Cr(VI) explained the observed differences. Increasing pH induced electrostatic repulsion, reducing adsorption of both pollutants. High concentrations of Na+ and Mg2+ caused charge shielding, potentially enhancing Cr(VI) adsorption but inhibiting SMX adsorption due to competition for active sites. The presence of organic matter (humic acid) had negligible effects on Cr(VI) adsorption but reduced SMX adsorption, likely due to complexation. These findings elucidate distinct molecular-level pathways for organic versus inorganic pollutant adsorption on aged MPs, highlighting the roles of hydrogen bonding and pore-filling in driving differential behaviors.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3898-7
Platinum (Pt) is the benchmark catalyst for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in acidic electrolytes, but its performance in alkaline media is limited by excessively strong hydrogen binding energy (HBE). Here, we report oxygen-modified ultrasmall RuCu nanocrystals (RuCu/C-200) as an efficient catalyst for both alkaline HER and HOR. The RuCu/C-200 catalyst exhibits excellent HER activity with an overpotential of 9 mV at 10 mA cm−2 and a Tafel slope of 19.7 mV dec−1. For HOR, it achieves a 4.2-fold higher exchange current density than the unannealed sample. Mechanistic studies reveal that the optimized HBE, hydroxyl binding energy (OHBE), and strongly hydrogen-bonded interfacial water, induced by oxygen modification, are the intrinsic determinants of the improved catalytic activity. This work underscores the potential of combining nanoscale structural design with oxygen modification to develop high-performance Ru-based electrocatalysts for both alkaline HER and HOR.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3794-0
Luminescent transparent display technology is widely used in emerging fields such as augmented reality glass, head-up vehicle display, and commercial retail windows. While electroluminescent display is well established, the photoluminescent transparent screen of full-color rendering ability remains elusive due to the severe crosstalk between emitters. Herein, a full-color transparent screen of an orthogonal red/green/blue (R/G/B) luminescence is reported. Lanthanide fluoride nanocrystals are used as the emitters, where the color is tuned by a deliberate choice of doping activators including Tb3+, Eu3+, and Tm3+. Polyvinyl alcohol, with an identical refractive index to nanocrystals, is employed as the host matrix, enabling a high transparency up to 86% in the visible region upon a high loading content (~78 wt%) of nanocrystals. It should be noted that the nanocrystals are embedded in separate monolayers before integration by a UV-selective absorber, i.e., epoxy resin, which absorbs 254-nm UV to block cross-excitation between Tb3+ and Eu3+ layers, providing an asymmetric luminescent property from both sides of the screen. In a proof-of-concept experiment, a full-color prototype is showcased in real time for its potential applications in advanced displays of immersive experience.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3783-x
The synergistic strategy combining chemotherapy and immunotherapy has recently demonstrated significant promise in cancer treatment. However, the substantial physicochemical disparities between chemotherapeutic agents and small-molecule immune adjuvants pose considerable challenges for co-delivery strategies. In this study, we designed a reactive oxygen species-responsive paclitaxel prodrug, PTX-PBA, which markedly enhanced drug encapsulation stability and dual-drug loading efficiency by various polymeric delivery systems. The resultant nanosystem (NanoPR) exhibited excellent physicochemical properties and ROS-triggered release profiles, effectively inducing immunogenic cell death in tumor cells while promoting dendritic cell maturation and CD8+ T cells activation. In murine models of 4T1 breast cancer and CT26 colon carcinoma, NanoPR achieved significant tumor growth inhibition and elicited durable immune memory responses. Collectively, this work provides an innovative molecular design strategy for the co-delivery of chemotherapeutics and immunomodulators, offering a robust foundation for the clinical translation of chemo-immunotherapy.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3873-7
The escalating demand for lightweight, multifunctional stealth materials in modern protective applications necessitates integrated solutions against electromagnetic interference (EMI), infrared (IR) detection, and incendiary threats. This study presents an innovative melamine foam (MF)-based composite featuring an asymmetric dual-nano conductive network, achieving absorption-dominated EMI shielding, IR stealth, and flame retardancy. Inspired by the Salisbury screen, the composite employs MF as an interlayer and flame-retardant thermoplastic polyurethane (TPU) nanofiber membrane as a substrate. The architecture comprises a carbon nanotubes (CNTs)-modified impedance matching nanofiber layer as the top absorber and a silver nanoparticles (AgNPs)-modified nanofiber layer as the highly conductive reflective bottom. Precise control of CNTs content and interlayer thickness enables tunable electromagnetic wave (EMW) absorption, yielding a low reflection coefficient of 0.03 and a high EMI shielding effectiveness of 79.23 dB at a total thickness of 4.40 mm. Even at 1.40 mm, effective absorption-dominated shielding is maintained. The performance remains stable under ultrasonic, compression, and bending tests, demonstrating high durability. The mechanism underlying absorption-dominated EMI shielding at reduced thickness, relying on destructive interference of EMWs enabled by the asymmetric dual-nano conductive network, is thoroughly elucidated. Additionally, the composite exhibits superior IR stealth and self-extinguishing properties. This work offers a feasible strategy for designing high-performance stealth materials with strong potential for personnel and communication equipment protection.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025032601
This study investigated the pollution characteristics of chlorate and perchlorate in tea from Anhui region and assessed the health risks associated with tea consumption. A total of 132 tea samples, including green tea (n=89), black tea (n=30), yellow tea (n=10), and white tea (n=3), were collected from major tea-producing areas. Chlorate and perchlorate levels were quantified using isotope dilution liquid chromatography-tandem mass spectrometry. Chlorate was detected in 15.9% of samples, with concentrations ranging from not detected to 0.040 mg·kg−1, and no samples exceeded the regulatory limit. Perchlorate was detected in 100% of samples, with concentrations ranging from 0.011 to 1.611 mg·kg−1, and 2.3% of samples exceeded the limit. Pollution characteristics analysis revealed that perchlorate levels were significantly correlated with tea type and geographical origin, with environmental contamination in tea-growing areas being the primary determinant. A significant positive correlation was also observed between chlorate and perchlorate levels. Health risk assessments were conducted for the general tea-consuming population, sub-groups loyal to specific tea types (green and black tea), and sub-groups preferring local tea from high-pollution regions (Lu'an City and central Anhui). Assessments were based on mean and 95th percentile (P95) exposure levels. For chlorate, the maximum hazard quotient (HQ) was 0.003, far below 1, indicating negligible risk. For perchlorate, all HQ values were below 1, regardless of tea type or region, based on both mean and P95 levels, using the Chinese provisional tolerable daily intake (tTDI). However, perchlorate contamination in central Anhui, particularly Lu'an City, warrants continued monitoring due to elevated levels and occasional exceedances.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3939-4
Broadband near-infrared (NIR) phosphors with longer wavelengths are critically needed for deep-tissue biomedical imaging and other emerging applications. However, the detailed mechanism of Mn2+-activated NIR emission remains elusive. Guided by the nephelauxetic effect theory, sulfide phosphors with strong covalent bonding are promising for achieving long-wavelength Mn2+ luminescence. This work reports a series of M(Ga, In)2S4:Mn2+ (M = Ca, Sr, Ba) phosphors featuring strong crystal field environments, and for the first time the luminescence behaviors of Mn2+-doped MIn2S4 (M = Sr, Ba). Preferential site occupancy leads to significant differences between MGa2S4:Mn2+ (M = Ca, Sr) and MIn2S4:Mn2+ (M = Sr, Ba) despite the same crystal structure. Severe polyhedral distortion enhances ultrawideband deep-red to NIR luminescence (600–850 nm, FWHM ≈ 123–257 nm), far superior to similar materials. Fabricated pc-LED devices demonstrate excellent vascular imaging and plant illumination capabilities. This study provides new insights into the NIR luminescence of isolated Mn2+.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60762-1
The CO2 dry reforming of methane (DRM) is pivotal for CO2 utilization within the dual-carbon framework, offering advantages in carbon reduction and value-added chemical production. However, shaped catalysts suitable for industrial-scale DRM remain limited. This work constructs a monolithic catalyst using honeycomb cordierite as the structural support, systematically investigating the effects of organic and inorganic binders on coating structure and catalytic performance. Comparative studies reveal that the active coating fabricated with inorganic aluminum sol exhibits a continuous uniform morphology and excellent adhesion strength. During high-temperature calcination, elemental diffusion within Al2O3 networks bridges the cordierite surface with active catalyst particles, forming a (Ni-Mg)AlxO4 composite structure. This creates robust metal-support interactions between active sites and the residual alumina matrix. The interconnected mesoporous framework provides superior pore confinement, contributing to strong coating adhesion, enhanced activity, and improved resistance to carbon deposition in the monolithic m-NCM-Al-sol catalyst. In contrast, coatings derived from inorganic silica sol suffer from detachment and activity loss due to heterogeneous surface structures and poor adhesion. Organic binders demonstrate inferior performance in macroscopic coating uniformity, adhesion strength, mesoporous confinement, and localized electronic effects, resulting in the poorest catalytic performance. By optimizing aluminum sol coating parameters—binder content, active component dosage, and coating cycles—a synergistic balance between coating thickness and mass transfer is achieved. The optimized catalyst demonstrates excellent DRM performance, providing insights for constructing high-performance shaped catalysts with cordierite coatings.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3587-4
Unstable zinc interfaces arising from dendrite growth and parasitic reactions impede the practical deployment of rechargeable aqueous zinc-ion batteries. This study introduces 1-(2-pyridylazo)-2-naphthol (PAN) as a parts-per-million (ppm) level electrolyte additive to stabilize the Zn anode. Theoretical and experimental analyses reveal that PAN undergoes parallel adsorption on the Zn surface, establishing strong π-π interactions between adjacent molecules that efficiently repel water. The OH, pyridine N, and azo N groups in PAN chelate Zn2+, modulating Zn2+ diffusion and promoting uniform deposition while suppressing dendrite formation. A 10 ppm (0.04 mM) PAN addition extends the lifespan of a symmetrical cell to 1500 h at 2 mA cm−2 and 1 mAh cm−2. The Zn||Cu half-cell achieves a Coulombic efficiency of 99.91% over 3500 cycles at 5 mA cm−2 and 1 mAh cm−2. Full cells with NH4V4O10 and MnO2 cathodes exhibit enhanced cycling stability. Notably, a Zn||NH4V4O10 pouch cell retains 71.1% capacity after 250 cycles at 0.8 A g−1. This work demonstrates a viable strategy for selecting high-efficiency additives for aqueous metal-based batteries.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3680-8
Two-dimensional (2D) materials with ultrawide band gaps and strong, tunable second-harmonic generation (SHG) coefficients are critical for miniaturized deep-ultraviolet (DUV) nonlinear optical (NLO) devices. Despite extensive experimental synthesis of 2D materials, none have satisfied DUV NLO requirements. Here, an experimentally available graphene-like BeO monolayer composed solely of NLO-active [BeO3] units is identified as an excellent 2D DUV NLO material via first-principles calculations. It exhibits an ultrawide band gap of 6.86 eV and a strong SHG coefficient χ22(2)(2D) = 6.81 Å pm/V. Through stacking, strain, and twist engineering, numerous 2D BeO sheets are predicted, and their flexible structural characteristics enable tunable NLO properties. Remarkably, extremely stress-sensitive out-of-plane χ15(2)(2D) and χ33(2)(2D) (with an exceptional 30% change) and robust in-plane χ22(2)(2D) against large strains are achieved together in AC- and ACE-stacked BeO sheets under in-plane biaxial strain, exhibiting emergent phenomena uniquely not observed in other known 2D NLO materials. These results establish 2D BeO systems as a new option for 2D DUV NLO materials.