Science Bulletin最新文献

Mg₃(Sb,Bi)₂-based thermoelectrics (TEs) show promise for near-room-temperature energy conversion and TE-cooling applications. However, further improvements in electrical power factors and figure-of-merits (zTs) are constrained by precise Mg-vacancy regulation and elucidation of underlying mechanisms. Herein, we report a novel in-situ Mg-vacancy engineering strategy in Mg₃(Sb,Bi)₂ where excess Mg is generated from local reactions between a selection of specific transition metals and the component anionic element(s) in Mg₃(Sb,Bi)₂ during spark-plasma-sintering. This process effectively refills matrix Mg-vacancies through the subsequent global diffusion of Mg cations in Mg₃(Sb,Bi)₂ lattices. This local-reaction-global-diffusion concept, contrasting with reported mechanisms associated with localized grain-boundary engineering, is elaborated through multiscale investigation. Vacancy-restrained Mg₃(Sb,Bi)₂ demonstrates remarkably enhanced carrier mobility and zTs, achieving record-high power factors. Our fabricated Mg₃Sb_0.5Bi_1.5/MgAgSb and Mg₃SbBi/MgAgSb modules achieve record-high dual-output performance with power-density/efficiency values of 1.23 W cm^-2/11.7% and 1.05 W cm^-2/12.8%, respectively, under a temperature difference (ΔT) of 315 K. The constructed Mg₃Sb_0.5Bi_1.5/Bi_0.5Sb_1.5Te₃ and Mg₃Sb_0.75Bi_1.25/Bi_0.5Sb_1.5Te₃ Peltier modules deliver competitive cooling ΔT_max exceeding 70 and 67 K, respectively, at 303 K. The concept is expected to extend to the defect engineering of other energy materials (e.g., SnTe and PbSe TEs), TE-interface materials, and metal-semiconductor interfaces with optimized functionalities.

Developing single-pixel color-tunable electroluminescence technology represents a practical approach to circumvent current limitations in pixel processing and longevity. However, existing single-pixel color-tunable quantum dot light-emitting diodes (QLEDs) devices predominantly employ complex tandem structures. Herein, we demonstrate single-layer color-tunable QLEDs by the real-time interface exciplex modulation with AgInZnS (AIZS) quantum dots (QDs). The dynamically color-tunable QLEDs based on green- and red-emitting AIZS QDs exhibit broad spectral coverage, spanning from green to blue, red to yellow, as well as standard white emission. The fabricated devices achieve a leading maximum external quantum efficiency of 5% for quaternary alloy AIZS-based QLEDs. Furthermore, we successfully demonstrate patterned and large-area QLEDs, systematically confirming their significant potential for application in full-color display and lighting technologies.

Humans have changed planetary boundaries; the depletion of virgin minerals and accumulation of urban minerals are occurring. In contrast to geological resources, the scientific classification of anthropogenic resources remains unsolved. Clarifying where, when, how many, and how various urban minerals accumulate and can be extracted is crucial for fostering a circular economy material "closed loop". To this end, we developed a structural and evidence-based quantifiable classification method to explore the availability (resource) and accessibility (reserve) of urban minerals. Using China's electric and electronic equipment and automobile industries as a case study, our analysis indicates that the annual urban minerals "formation" in 2023 has reached 27 million tons. Among 42 target metals, eight were mineable, 26 were unmineable, and the remaining eight were swinging between mineable and unmineable across scenarios. Furthermore, we found that enhancing separation and recovery ratios for Fe, Al, Cu, and precious metals can further reduce reliance on natural sources for these minerals by 9%-15% and that optimizing recycling value thresholds for the other 37 metals (e.g., rare earth elements and light metals) can replace the need to mine 7%-42% of these virgin minerals, potentially raising present circularity of electrical and electronic equipment and automobiles from one-third to half. This study reveals the "availability-accessibility" gradient structure of urban minerals and its coupling across policy, technological, and economic dimensions, offering scientific support for building urban mineral databases, formulating urban mining policies, and promoting the implementation of urban mining.

Crop diversity underpins the stability of food supply and the sustainability of agriculture, yet a limited understanding of its variability and underlying drivers constrains effective management. Drawing on data from 211 countries over six decades (1961-2020), we show that global crop diversity has generally increased, although one-third of countries experienced declines, and crop evenness decreased in nearly half of the countries. Differences across nations are primarily shaped by farm size, multiple cropping intensity, farmers' crop income, and crop consumption patterns. Farm size emerges as the dominant factor, reducing global crop diversity by approximately 4%-8% annually from 1961 to 2020 and amplifying global inequalities in crop diversity distribution. Projections indicate a further 3%-10% decline by 2050 relative to 2020 levels. However, this trajectory can be reversed, with effective farm size management yielding a 6%-17% increase in global crop diversity while narrowing inter-country disparities. Such progress is critical to strengthen agricultural stability and advance multiple UN Sustainable Development Goals, including zero hunger, reduced inequality, and responsible consumption and production.

The rapid rise in lake surface water temperature (LSWT) over the past few decades has become a global concern. Research on the spatial heterogeneity of lake warming and its mechanistic drivers is a key challenge. Studies have shown that urbanization induced impermeable surface expansion can lead to the warming of inland waters, however, large scale studies are limited, and the driving mechanisms remain unexplored. To address this knowledge gap, we analyzed the thermal characteristics of 587 major lakes across China and found significant regional differences in LSWT trends. Specifically, LSWT increased in highly urbanized and densely populated regions (0.19 ± 0.05 °C 10a^-1) was 58.3% greater than in less urbanized regions (0.12 ± 0.03 °C 10a^-1) (P < 0.05). Additionally, our findings indicate that the warming rate in urbanized lakes (0.16 ± 0.05 °C 10a^-1) is 33.3% higher than in non-urbanized lakes (0.12 ± 0.03 °C 10a^-1) (P < 0.05). Moreover, urbanized lakes with high urbanization intensity (UI) (0.21 ± 0.04 °C 10a^-1) have warmed 31.3% faster than those with low UI (0.16 ± 0.05 °C 10a^-1) (P < 0.05). An importance assessment suggested that urbanization modified the impact of air temperature (ΔAT = 32.0%), precipitation (ΔP = -14.9%), and evapotranspiration (ΔET = -13.4%) on LSWT warming. Under the combined influences of urbanization and future climate change, lake surface waters are expected to warm further. These findings offer valuable insights for assessing LSWT trends, particularly in regions experiencing both urban expansion and changing climate conditions.