SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3755-8
Lead-free piezoelectric ceramics, including potassium sodium niobate (KNN), bismuth sodium titanate (BNT), and barium titanate, are promising alternatives to lead-based counterparts due to environmental regulations. However, their functional properties—piezoelectric coefficient, mechanical quality factor, dielectric loss, Curie temperature, and thermal stability—remain inferior. Oxygen vacancy engineering has emerged as a key strategy to optimize these properties via defect modulation. Oxygen vacancies, prevalent point defects, arise from high-temperature processing, non-stoichiometry, volatile oxide evaporation, or reducing atmospheres. Acceptor doping and post-processing annealing further increase their concentration. These defects influence electrical conduction, piezoelectric/dielectric behavior, and catalytic activity. They exist as lattice vacancies, domain wall vacancies, grain boundary vacancies, and defect dipoles with cation vacancies. Their presence induces lattice distortion, hinders domain wall motion, increases coercive field, and enhances mechanical quality factor via hardening. Defect dipoles align with spontaneous polarization, creating internal bias fields that pin domains, reducing losses. Quantification of oxygen vacancies remains challenging; concentrations below 1 at% in NBT and KNN are difficult to detect. Techniques like XPS have reliability issues. A combination of impedance spectroscopy, XPS/STEM, EPR/PAS is recommended. Defect chemistry modeling, using acceptor doping to fill vacancies, allows inference of non-stoichiometry ranges. For NBT, Bi deficiency of 0.0017–0.0033 and O deficiency of 0.0025–0.0050 were calculated, corresponding to Na0.5Bi0.4967–0.4983TiO3.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3685-7
NiMo-based catalysts are promising for the hydrogen evolution reaction (HER), yet optimizing their electronic structure and enhancing mass transfer remain challenging. Here, we report a route to synthesize two-dimensional (2D) porous Mo2N-Ni heterojunction nanosheets with tuned Ni/Mo ratio for enhanced alkaline HER. The precursor is assembled from polyoxometalate clusters (PMo12) and layered Ni(OH)2. The interaction between PMo12 and Ni(OH)2 suppresses particle agglomeration during pyrolysis, yielding 2D porous sheets composed of small Mo2N-Ni units. Electron transfer from Ni to Mo2N redistributes electrons at the heterojunction, optimizing intermediate adsorption/desorption. The porous structure enhances mass transfer, reducing catalyst impedance. The optimized catalyst exhibits an overpotential of 19 mV at 10 mA cm−2, comparable to commercial Pt/C. An anion exchange membrane (AEM) electrolyzer pairing this catalyst with NiFe-LDH achieves 500 mA cm−2 at 1.80 V and operates stably for 300 h. This assembly method offers a scalable strategy for efficient catalyst production.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202503016
Open-pit coal mining severely damages soil and plant community structure and function, causing soil nutrient loss and ecological degradation. Vegetation reconstruction is a key measure for restoring degraded mining ecosystems, with the core challenge being the selection of suitable plant species and optimization of plant configurations. This study focused on the degraded ecosystem of the Baiyinhua open-pit mine in Inner Mongolia, screening native plant species for vegetation reconstruction experiments to investigate early-stage changes in soil nutrient availability and the underlying microbial mechanisms. Results showed that soil physicochemical properties and fungal community diversity exhibited strong adaptability during early reconstruction. However, soil fungal community composition and the relative abundance of saprotrophic fungi differed significantly among plant configurations. Leymus chinensis significantly increased the proportion of soil saprotrophic fungi from 67.28% in the control to 81.63%, while reducing the relative proportion of pathogenic fungi from 15.63% to 4.33%, demonstrating its potential to enhance soil health. Medicago rivularis improved soil microbial community composition and increased soil available phosphorus content, highlighting its capacity as an excellent pioneer species for optimizing soil nutrient availability. Furthermore, mixed sowing of grasses and legumes showed potential to enhance the nitrogen-fixing effect of legumes. Given the significant positive correlation between soil fungal community composition and total nitrogen and available nitrogen, the effects of different plant configurations on soil nutrient availability and biological health likely stem largely from the regulation of soil fungal community composition. In conclusion, achieving the goal of selecting optimal plant configurations still requires long-term continuous observation and analysis, particularly for optimizing configurations between high-quality grasses like Leymus chinensis and legumes.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3962-y
Photochromic Förster resonance energy transfer (pc-FRET)-based subnanometric polymersomes with accurate color control offer a transformative yet challenging tactic for advanced and custom-tailored information encryption. Herein, various amphiphilic alternating pyrene/azobenzene-containing copolymers were polymerized using one-pot Ugi four-component polycondensation. Subsequent self-assembly was performed to produce highly-integrated monolayer subnanometric polymersomes (MSNPSs) and their composites, with diameters of around ~250 nm and vesicular thicknesses of approximately ~12.0 Å. J-aggregated monolayer chain-folding mechanism was accountable for the donor-acceptor-donor stacking manner within the vesicular membrane, beneficial to achieve highly efficient energy transfer. The trans-to-cis photoisomerization of azobenzenes rendered MSNPSs and their composites with photo-triggered structural transitions in diameter and vesicular thickness. Benefitting from considerable spectral overlap between cis-azobenzene and pyrene, MSNPSs and their composites were capable of photo-controllable non-invasive pc-FRET performance with a wide Stokes shift (~320 nm). The accurate color variation from blue to red highly depended upon precise modulation of both irradiation duration and precursor-fixed donor/acceptor ratios. The proof-of-concept individually multichromatic 2D QR code was attained using photochromic MSNPSs and their composites in patterning lithography, displaying a multimodal decryption and favorable repeatability for high-level and personalized information protection. Our work paves a prospective avenue to meticulously craft stimuli-chromatic polymersomes for the potential of advanced information encryption.