SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4420-7
Cu2-xSe is a leading p-type thermoelectric material owing to its phonon-liquid electron-crystal (PLEC) behavior, yet the atomic-scale mechanisms governing Cu+ migration remain unresolved. This study employs in situ high-resolution neutron diffraction coupled with maximum entropy method (MEM) analysis to map the temperature-dependent evolution of Cu+ nuclear density in β-Cu2Se and β-Cu1.95Se. At 398–423 K, intra-tetrahedral Cu 8c ↔ 32f <111> hopping emerges, with isosurface values of 0.505 fm Å-3 for β-Cu2Se and 0.484 fm Å-3 for β-Cu1.95Se. Above 448 K, inter-tetrahedral pathways form via Cu 32f ↔ 32f <100> or 32f ↔ 4b ↔ 32f <111> migration, as revealed by line scans along [1̅11̅] up to 723 K. The presence of Cu vacancies (x = 0.05) alters the onset and connectivity of these pathways, directly impacting phonon scattering and electron transport. These findings establish a structural basis for controlling Cu+ mobility, offering a rational route to mitigate Cu precipitation and enhance zT stability beyond 1.5 at 900 K. The work bridges microstructural dynamics and thermoelectric performance, providing critical guidance for defect engineering in superionic thermoelectrics.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4239-2
The sluggish kinetics of the oxygen evolution reaction (OER) remains a bottleneck for efficient water splitting. NiFe-layered double hydroxides (LDHs) are promising OER catalysts, but their performance is often limited by the high-spin state of Fe3+ and poor structural stability. Here, we report a series of amino acid-intercalated iron-rich NiFe-LDHs (AA-NiFe-LDHs) synthesized via a facile one-step coprecipitation method. Intercalation of glycine, alanine, and valine into the interlayer galleries expands the interlayer spacing and induces a partial transition of Fe3+ from high-spin to low-spin state, as confirmed by X-ray absorption spectroscopy and Mössbauer spectroscopy. The low-spin Fe3+ enhances the intrinsic catalytic activity by optimizing the adsorption energy of oxygen intermediates. Among the series, the glycine-intercalated sample (Gly-NiFe-LDH) exhibits the best OER performance in 1.0 M KOH, with an overpotential of 240 mV at 10 mA cm−2 and a Tafel slope of 38 mV dec−1, significantly outperforming the pristine NiFe-LDH (280 mV, 52 mV dec−1). Moreover, Gly-NiFe-LDH shows excellent long-term stability, retaining 95% of its initial activity after 24 h of chronopotentiometry at 10 mA cm−2. The intercalation also increases the electrochemically active surface area by 2.3-fold and reduces the charge transfer resistance from 12.5 Ω to 4.8 Ω. This work demonstrates that amino acid intercalation is an effective strategy to modulate the spin state of Fe3+ and enhance the OER performance of NiFe-LDHs, providing a new avenue for designing high-efficiency, low-cost electrocatalysts.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202506005
The escalating generation of medical waste, driven by healthcare expansion and frequent medical activities, poses significant environmental and public health risks. Under the framework of ecological civilization, China is developing a comprehensive policy system for medical waste treatment and disposal, yet the current framework remains nascent and exhibits inconsistencies between national and local policies. This study systematically analyzes the status of national and local policies from 2003 to 2024, collecting 413 policy documents (166 from national ministries and 247 from provincial governments). The analysis examines temporal evolution, regional distribution, and policy focus, alongside the influence of medical waste output, treatment technologies, facility infrastructure, and major epidemic responses. Findings reveal distinct policy phases: initial self-disposal, exploratory management, foundational system building, and rapid development. Regional disparities are pronounced, with eastern coastal areas showing more advanced policies due to greater technical and financial resources. The surge in medical waste, particularly during the COVID-19 pandemic, underscores the need for enhanced regulatory guidance. Non-incineration technologies are gaining traction for their environmental and cost benefits, and facility coverage has improved but remains uneven. The study proposes five policy principles to foster technological innovation and industrial upgrading, ensuring safe medical waste management and environmental protection.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4094-8
Deep-blue multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters with high efficiency, high color purity, and high brightness are critically important for next-generation OLED displays, yet remain challenging due to severe aggregation and host-guest interactions in the solid state. Herein, we report a core-encapsulating molecular design strategy in which bulky and non-conjugated peripheral groups are introduced to sterically encapsulate a blue-emitting MR core, thereby suppressing intermolecular π-π interactions without perturbing its intrinsic electronic structure. Two new emitters, DNa-BN and QNa-BN, featuring half-encapsulated and fully encapsulated MR-core architectures, respectively, were developed. Owing to its fully encapsulated structure, QNa-BN exhibits pronounced aggregation resistance at high doping concentrations, maintaining photoluminescence quantum yields exceeding 96%, radiative decay rate constants on the order of 10^8 s−1, and fast reverse intersystem crossing rates (~10^5 s−1). Consequently, sensitizer-free OLEDs based on QNa-BN deliver narrowband deep-blue emission at 458 nm with a full width at half maximum of 22 nm, CIE coordinates of (0.142, 0.085), a maximum external quantum efficiency (EQE_max) of 34.4%, and a maximum luminance exceeding 20,000 cd m−2. Furthermore, by adopting a hyperfluorescence architecture, the EQE_max is further boosted to 38.7% with significantly suppressed efficiency roll-off. This work demonstrates that steric encapsulation of the MR core provides an effective and general approach to achieving aggregation-resistant, high-efficiency, and high-brightness deep-blue MR-TADF emitters for OLED applications.
The Chinese Journal of Process Engineering•2026•DOI: 10.12034/j.issn.1009-606X.225162
The effects of tempering temperature on the microstructure, strength-toughness balance, and precipitates of a quenched Cu-Cr-Ni ultra-high strength weathering steel were systematically investigated. The steel was austenitized at 920°C, quenched, and then tempered at 500°C, 550°C, and 600°C. Microstructural characterization was performed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), while mechanical properties were evaluated via tensile and low-temperature impact tests. Results showed that as the tempering temperature increased from 500°C to 600°C, the microstructure transformed from lath-shaped tempered sorbite to a non-lath morphology. The fraction of rod-like cementite decreased, while spheroidized cementite increased, and the size of MC (M = Ti, Nb, V, Mo) precipitates decreased from an average of 12.2 nm to 9.9 nm. Consequently, yield strength and tensile strength decreased from 935 MPa and 958 MPa to 866 MPa and 888 MPa, respectively, whereas total elongation and impact energy at -40°C increased continuously, reaching maximum values of 5.0% and 280 J at 600°C. When tempered at 550°C, the steel exhibited a yield strength of 895 MPa, tensile strength of 921 MPa, elongation of 4.3%, and impact energy of 271 J at -40°C, demonstrating an optimal combination of strength and toughness. This improvement is primarily attributed to the spheroidization of cementite and the uniform dispersion of fine MC precipitates, which alleviate stress concentration, along with the softening of the acicular ferrite matrix during tempering.