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ZK
Verified CAS / Academic Author14 Decoded Studies

Prof. ZHANG Kai

Suzhou Institute of Nano-tech and Nano-Bionics, Chinese Academy of Sciences

Co-Affiliations:Not specified in textUniversity of Science and Technology of ChinaInstitute of Nuclear and New Energy Technology, Tsinghua UniversitySchool of Environment and Ecology, Xiamen University, Xiamen, 361005, ChinaNorth China Electric Power University

Research Publications & English Decoded Briefs

Showing 14 publications
SCIENCE CHINA Materials2026DOI: 10.1007/s40843-026-4263-3

Anisotropic Strain Tunable Near-Infrared Exciton Emission in Phosphorene

Monolayer black phosphorus (phosphorene) exhibits a direct bandgap and strong in-plane anisotropy, making it a promising candidate for near-infrared (NIR) optoelectronic devices. However, the precise modulation of its excitonic emission via anisotropic strain remains insufficiently understood, particularly regarding the contrasting strain responses of phosphorene versus transition metal dichalcogenides (TMDs). Here, we combine experimental characterization with tight-binding (TB) modeling to elucidate the strain-dependent bandgap evolution in phosphorene. Using a four-band TB model, we derive the bandgap at the Γ point as E_g^BP = 4t1 + 2t2 + 4t3 + 2t5, with hopping parameters t1 = -1.220 eV, t2 = 3.665 eV, t3 = -0.205 eV, t4 = -0.105 eV, and t5 = -0.055 eV. Under tensile strain along the zigzag (ZZ) direction, the interatomic distance associated with t1 increases, reducing the magnitude of |t1|. Since t1 is negative, the bandgap increases, contrary to the behavior of monolayer MoS2, where tensile strain decreases the bandgap due to positive hopping parameters t11, t22, and t12. This anisotropic strain response enables selective tuning of NIR exciton emission. Our findings provide a quantitative framework for strain engineering in phosphorene-based NIR devices, highlighting the critical role of hopping parameter signs in determining bandgap modulation.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3841-6

Synergistic Bulk and Interface Engineering Empowering Exceptional Lithium Storage Performance of Ni-Rich Cathodes

Ni-rich layered oxide cathodes are pivotal candidates for next-generation lithium-ion batteries (LIBs) due to their high capacity and energy density. However, their susceptibility to structural deterioration and interfacial degradation during cycling causes substantial capacity fade, hindering commercialization. This work proposes a synergistic strategy of lattice doping and in situ surface coating to enhance structural integrity and interfacial stability of LiNi0.9Co0.05Mn0.05O2. La and Y dopants act as pillars to reinforce the layered structure, mitigating volume changes and expanding c-axis spacing to facilitate Li+ diffusion. Concurrently, La4NiLiO8 and LiYO2 coatings protect the cathode from H2O/CO2 corrosion and electrolyte attack, while their high lithium-ion conductivity promotes Li+ transport. The modified cathode delivers exceptional electrochemical metrics: high specific capacity of 207.3 mA h g−1, remarkable cycling stability with 97.6% retention after 100 cycles, superior rate capability of 152.1 mA h g−1 at 10.0 C, and enhanced thermal stability. This work establishes a paradigm for multi-dimensional stabilization of Ni-rich cathodes via synergistic bulk and interface engineering, providing insights for designing high-performance energy storage systems.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3793-9

High-efficiency hybrid planar/bulk heterojunction organic solar cells

Organic solar cells (OSCs) require both a high donor/acceptor (D/A) interfacial area for efficient exciton dissociation and a vertically phase-separated morphology for efficient charge transport. Traditional bulk heterojunctions (BHJs) provide large interfacial areas but lack vertical phase separation, while quasi-planar heterojunctions (QPHJs) achieve vertical separation at the cost of reduced interfacial contact. Here, we introduce an in situ pore-forming strategy for polymer thin films. By incorporating an excess of additives as pore-forming agents into the donor layer, a nanoporous film with a fibrous nano-network is generated. Subsequent deposition of acceptor molecules fills these nanopores, creating a hybrid planar/bulk heterojunction (HP/BHJ) that synergizes the strengths of both architectures. This design enhances performance by: (1) increasing the D/A interfacial area via nanopores, forming a three-dimensional network that accelerates exciton dissociation; (2) promoting close molecular packing that minimizes carrier recombination and establishes low-defect charge transport channels; and (3) fostering vertical phase separation through layer-by-layer deposition. Binary OSCs fabricated with this strategy achieve a power conversion efficiency (PCE) of 20.0%, surpassing conventional BHJ and QPHJ devices by a significant margin. The approach demonstrates general applicability, with analogous improvements observed in D18/BTP-eC9-4F and PM6/L8-BO systems, underscoring its potential for advancing OSC performance.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3600-1

Computational Screening of 2D Pentagonal Materials with Room-Temperature Altermagnetism, Multiferroicity, and Topological States

Two-dimensional planar pentagonal crystals, long pursued for their geometrically frustrated lattice configurations and emergent quantum phenomena, have remained challenging to realize due to the intrinsic incompatibility of regular pentagons with Euclidean tiling. Here, we unveil 37 dynamically stable binary planar pentagonal monolayers through high-throughput computational screening of 1470 stoichiometric candidates. These materials exhibit room-temperature magnetism, including ferromagnetic (Curie temperature up to 521 K), antiferromagnetic (Néel temperature up to 761 K), and altermagnetic (Néel temperature = 984 K) ground states, alongside unprecedented electronic states: Dirac semimetals, Dirac half-metal, nodal-loop semimetal, nodal-loop half-metal, and altermagnetic semiconductors (Mn4N2) with giant spin splitting (0.78 eV). The latter achieves pure spin-polarized transport windows (−0.04 to 0.36 eV) and strain-tunable valley splitting (18.2 meV under 4% uniaxial strain). Intrinsic type-II multiferroicity emerges in Fe4C2 and Mn4C2, featuring in-plane electric polarization (1.4 and 1.6 pC/m), ferroelasticity (0.8% and 1.2% reversible strain), and reversal chirality. Topological band analysis identifies chiral edge states in Dirac semimetal pentagons, alongside a magnetic topological insulator with Chern number |C| = 2 in Mo2S4 and W2Te4. Temperature-driven structural transitions in Os2S4 and Tc2S4 from pentagonal to Lieb lattices accompany topological state switching and metal-to-semiconductor transitions. This work establishes pentagonal lattices as a platform for symmetry-driven multifunctionality, bridging geometric frustration with applications in spintronics, nanoelectronics, and quantum devices.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3628-3

Regulating Solution Aggregation and Entanglement for Efficient Self-Powered All-Polymer Photodiodes in Water Quality Monitoring

The solution aggregation structures of conjugated polymers are pivotal in determining their film morphology and optoelectronic properties, yet the relationship between solution aggregation and device performance remains elusive in organic photodiode (OPD) systems. Herein, we introduce the first examination of solution aggregation structures of all-polymer OPD blends, with a focus on how molecular entanglement modulates aggregation behavior and subsequent photodiode performance of low-cost poly(3-pentylthiophene). Using small-angle neutron scattering and freeze-dried imaging, we provide a comprehensive analysis of the solution-state aggregation behavior of poly(3-pentylthiophene) and its evolution in the blend, revealing profound impacts on film morphology and device performance. With finely optimized aggregation, the resulting all-polymer OPD achieves a record-high specific detectivity of ~4×10^13 Jones at zero bias, outperforming all bulk heterojunction (BHJ)-type self-powered OPDs reported to date. This device also demonstrates remarkable thermal stability, with negligible performance degradation after over 800 h of thermal annealing at 85 °C. Furthermore, the self-powered OPD exhibits excellent performance across a broad spectral range, enabling its application in both water quality monitoring and biosensing. This work offers new insights into the solution aggregation behavior of conjugated polymers in OPDs and highlights the importance of resolving solution aggregation in optimizing device function.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3654-5

Nanofunctionalized Chlorella cells with photo stimulation for biological hydrogen production

Hydrogen production by photosynthetic green algae is an efficient biological process that utilizes light energy to convert water and carbon dioxide into clean and renewable energy. In this paper, we constructed a hybrid system combining graphitic carbon nitride (g-C3N4) and Chlorella pyrenoidosa (Chlorella), in which g-C3N4 serves as an extracellular electron source and Chlorella acts as a biological reactor for specific hydrogen production. In particular, the electronic structure of carbon nitride was optimized by means of hydrothermal alkalization and copper ion doping, expanded the light absorption range and enhanced the light response ability. g-C3N4, as an extracellular electron source, can provide electrons for Chlorella to improve hydrogen production performance which is 3.7 times that of bare Chlorella. The construction of a biological hybrid system is a feasible optimization strategy for the hybrid system to promote the synergistic effect of the hybrid system by regulating the properties of non-living components.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3710-y

Closed-Shell Elements Li & Sn Substituted P2-Type Layered Cathode Materials for Wide-Voltage Sodium-Ion Batteries

Layered transition metal oxide cathodes for sodium-ion batteries (SIBs) suffer from Jahn–Teller distortion of MnO6, Na+/vacancy ordering, and irreversible lattice oxygen loss, causing capacity fading and voltage decay. Here, we report a P2-type material, Na0.67Ni0.3Mn0.6Li0.09Sn0.01O2 (NNMO-Li0.09Sn0.01), co-doped with closed-shell Li+ and Sn4+ ions. Li+ increases the Mn4+/Mn3+ ratio, mitigating Jahn–Teller distortion, and disrupts Ni/Mn ordering, suppressing Na+/vacancy ordering. Sn4+ forms stronger Sn–O bonds (548 kJ mol−1), enhancing bonding between transition metal ions and oxygen, reducing oxygen loss. NNMO-Li0.09Sn0.01 delivers a specific capacity of 90.3 mAh g−1 with 62.9% capacity retention after 50 cycles at 0.1 C (1 C = 200 mA g−1), and 90.3% voltage retention. This closed-shell substitution strategy offers a viable approach for enhancing structural stability of wide-voltage layered oxide cathodes.

New Carbon Materials2026DOI: 10.1016/S1872-5805(26)61113-4

Revealing Abnormal Micro- and Meso-Structure Evolution Mechanism of Porous Pyrolytic Carbon in TRISO Coated Fuel Particles under High-Temperature Treatment

Porous pyrolytic carbon (PPyC) serves as the buffer layer in TRi-structural ISOtropic (TRISO) fuel particles, providing storage for fission gases, preventing damage to outer layers, and absorbing stresses caused by fuel-kernel swelling. However, the changes of PPyC micro- and meso-structure at high temperatures remain insufficiently understood. In this study, PPyC fabricated by chemical vapor deposition was heat-treated from 1200 to 1600 °C and characterized across atomic-to-mesoscopic scales. Results show that the structure changes with temperature with a transition at approximately 1400 °C. Below 1400 °C, a decrease in Raman ID/IG ratio, narrowing of the graphite diffraction peak, and increased sp2 hybridization indicate progressive ordering associated with defect redistribution. Concurrent decreases in true density and mesopore volume, together with increased closed porosity, are consistent with partial conversion of open pores into closed pores. Above 1400 °C, increased ID/IG ratio, broadening of the diffraction peak near the rhombohedral graphite (101) reflection, and transition regions between crystalline and amorphous material observed by TEM indicate increasing structural disorder. Meanwhile, initially distinct PPyC particle boundaries blur and merge into broad, plate-like domains. Subsequent decrease in closed porosity and increase in mesopore surface area are consistent with partial connection of closed pores to the open-pore network. This work shows that intrinsic coupling between atomic-scale structural change and mesoscale pore connectivity provides a basis for assessing high-temperature structural stability of PPyC in TRISO fuel particles.

Environmental Chemistry2026DOI: 10.7524/j.issn.0254-6108.2025012001

Research Progress on the Application of Metal Nanozymes in Water Treatment

Nanozymes, nanomaterials capable of mimicking natural enzyme catalytic activity, exhibit exceptional stability, high catalytic activity, cost-effectiveness, and environmental friendliness, demonstrating immense potential in water treatment. This review article delves into the applications of metal nanozymes in water treatment, focusing on the pivotal roles of peroxidase-like, oxidase-like, and multi-enzyme active nanozymes. In this article, the central role of metals of nanozymes in the catalytic activity was analyzed, enhancing catalytic activity and the oxidation efficiency of pollutants. It is emphasized that the synergistic effect of bimetals further enhances catalytic activity and the oxidation efficiency of contaminants. This article offers profound insights into the catalytic mechanisms of nanozymes, providing a reference for selecting appropriate metals based on the characteristics of water pollution and developing metal nanozymes with specific catalytic activities.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3934-1

Bioinspired Reprocessable Dual Crosslinked Solid-Solid Phase Change Material for Solar-Assisted Thermal Energy Storage and Multi-Scenario Thermal Camouflage

Solar energy, a clean and abundant resource, can be stored as latent heat in solid-solid phase change materials (SSPCMs) and subsequently utilized, offering great potential for advancing passive thermal management technologies such as thermal camouflage. Conventional SSPCMs often require active heating for high-temperature conditions, leading to additional energy consumption. Moreover, their permanent crosslinked structures limit reprocessability and increase environmental burden. Herein, we present a lizard-skin-inspired, solar-thermal-responsive, and reprocessable SSPCM (FTSPCM) featuring a dual crosslinked structure composed of dynamic phenol–carbamate bonds and Fe3+@Tannic acid (TA) coordination. Polyethylene glycol (PEG) functions as the phase change segment, while TA introduces both reversible covalent crosslinking and photothermal responsiveness. The FTSPCM exhibits a high latent heat of 102.9 J g−1, excellent shape stability, and maintains its thermal performance after three reprocessing cycles at 120 °C. The Fe3+@TA coordination network enables strong near-infrared absorption and efficient solar-thermal conversion, achieving a surface temperature of 62 °C and a conversion efficiency of 96.85% under 2 Suns irradiation. This dual-function design allows the material to achieve passive thermal camouflage via latent heat release at low temperatures and solar-assisted photothermal heating at high temperatures. This work presents a sustainable strategy for developing reprocessable, solar-responsive SSPCMs, showcasing the distinctive advantages of tannic acid-derived polyphenol chemistry in constructing passive thermal management systems for energy-efficient thermal camouflage and solar-driven thermal energy storage.

Environmental Chemistry2026DOI: 10.7524/j.issn.0254-6108.2026031103

Speciation Analysis and Advanced Removal of Thallium from Washing Wastewater of Sintering Machine Head Ash

Sintering ash washing wastewater from steel plants is characterized by high salinity, high chloride content, high thallium load, and coexistence of multiple metals, posing significant treatment challenges. This study employed thermodynamic simulation to elucidate the speciation and transformation of thallium in such wastewater, and systematically investigated a combined process of sulfide precipitation coupled with coagulation-flocculation. The results showed that at pH 9–10, thallium predominantly existed as Tl+. Under oxidizing conditions, the stable complex anion [TlCl4]− dominated at pH < 8.1, while at pH > 8.1, a mixed system of solid Tl2O3 and dissolved TlClO3 coexisted. Under optimized conditions (pH 12, 2.0% thallium removal agent, 1.0% multi-effect auxiliary agent), the thallium concentration in the wastewater decreased from an initial 9.58 mg·L−1 to 4.31 μg·L−1, meeting the stringent discharge limit of ≤5 μg·L−1. Concurrent removal of Cu, Zn, and Cd was achieved. The primary removal mechanism was sulfide precipitation, with lattice substitution between Tl+ and K+ serving as an auxiliary pathway. This study provides a practicable technical route for advanced treatment of high-chloride, high-thallium industrial wastewater.

Journal of Fuel Chemistry and Technology2026DOI: 10.1016/S1872-5813(26)60690-1

Reaction mechanisms and cracking performance of CH4 provoked by non-equilibrium plasma

Methane cracking driven by electric power holds significant promise in the context of the rapid development of renewable energy. The effects of carrier gas ratio, input power, and inlet gas flow rate on CH4 cracking performance were systematically investigated in a dielectric barrier discharge (DBD) reactor. The variation of temperature distribution and reaction energy intensity were also examined. The experimental results indicate that CH4 conversion and gaseous product formation are promoted by increasing the DBD input power or decreasing the inlet gas flow rate. At an input power of 90 W and an inlet gas flow rate of 200 mL/min, the single-pass CH4 conversion reaches 46.6%, with an H2 yield of 23.3%, demonstrating that CH4 cracking is governed by electron induced reactions. While the Joule heating from the inner and outer electrodes is relatively limited. The reaction energy intensity increases as the CH4 conversion decreases. When the inlet gas flow rate increases from 200 to 800 mL/min, the energy intensity rises by approximately 2.8 times, indicating that higher inlet gas flow rates enhance the convective heat transfer and shorten the gas residence time, thereby suppressing deep CH4 cracking. Moreover, BOLSIG+ calculations further reveal that CH4 activation is dominated by electron induced vibrational excitation, in which stepwise energy accumulation drives C–H bond dissociation. The energy transfer and species transformation pathways of overall CH4 cracking process, which comprises electron energy injection, vibrational excitation, stepwise dissociation, radical chain extension, and final product formation, can be summarized into three stages, i.e. methane activation, radical evolution, and product formation.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-026-4109-2

Ambient Fabrication of Over 19% Efficient Organic Solar Cells via Spontaneous Water-Spreading and Layer-by-Layer Deposition

The fabrication of high-efficiency organic solar cells (OSCs) under ambient conditions remains a formidable challenge due to the sensitivity of active layer morphology to environmental factors. We propose an innovative approach for air-processed devices that combines spontaneous water-spreading film formation with layer-by-layer (LBL) deposition. This method enables the fabrication of donor- and acceptor-dominant bulk heterojunction blend films near the anode and cathode interfacial layers, respectively, optimizing vertical phase separation and enhancing charge transfer efficiency. In the D18:L8-BO system, the device achieves a power conversion efficiency (PCE) of 19.02% with an exceptionally narrow efficiency distribution. Even for devices with an area of 1 cm2, a PCE of 16.56% is attained. After a 1000-hour decay test, the efficiency retains 84.1%. This novel method offers a promising pathway for advancing the industrial application of large-area, highly stable devices with narrow efficiency distribution under ambient conditions.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-4016-3

Electromagnetic Wave Absorbing Materials Derived from Rare Earth Ions Enriched via Host-Guest Interactions in Anion Metal-Organic Frameworks

Rare earth-based electromagnetic wave (EMW) absorbing materials are promising due to their strong dielectric and magnetic loss capabilities, yet effective enrichment and utilization of rare earth ions remain challenging. Here, an anionic imidazolium-based metal-organic framework (MOF), MOZ-200, is employed to enrich multiple rare earth ions (La3+, Ce3+, Pr3+, Nd3+, Y3+) via host-guest interactions. The anionic framework uniformly confines these ions, which are converted in situ into highly dispersed high-entropy rare earth alloy nanoparticles during carbonization. The resulting HE@C composites feature a conductive, graphitized carbon matrix with abundant multi-scale polarization centers and heterogeneous interfaces, enhancing dipole polarization, interface polarization, and conductive loss. Consequently, the material achieves excellent EMW absorption in the Ku band, with a minimum reflection loss of -79.20 dB and a maximum effective absorption bandwidth of 5.23 GHz. Integrated into a polyurethane matrix, a multifunctional flexible device is realized, offering EMW absorption, photothermal heating, microwave de-icing, and hydrophobicity. This work provides a feasible strategy for rare earth ion utilization and advances the design of flexible multifunctional EMW absorbing materials.