Science, 25 OCT 2024, VOL 386, ISSUE 6720

《科学》2024年10月25日，第386卷，6720期

材料科学Materials Science

Reductive pathways in molten inorganic salts enable colloidal synthesis of III-V semiconductor nanocrystals

熔融无机盐还原途径实现III-V族半导体纳米晶的胶体合成

▲ 作者：JUSTIN C. ONDRY, ZIRUI ZHOU, KAILAI LIN, ARITRAJIT GUPTA, JUN HYUK CHANG, HAOQI WU, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.ado7088

▲摘要：

胶体量子点具有尺寸可调的光电特性和可扩展的合成，实现了廉价高性能半导体的应用。合成科学的突破是实现量子点技术的关键，但重要的III-V族半导体，包括胶体砷化镓（GaAs），仍然无法用现有方法合成。

研究组介绍的高温熔融盐胶体合成技术可用于制备此前难以处理的胶体材料。利用熔融盐氧化还原化学和使用表面活性剂添加剂来控制纳米晶形状，研究组在熔融无机盐中直接成核和生长胶体量子点。

425℃以上的合成温度是实现光致发光GaAs量子点的关键，这强调了熔融盐溶剂实现高温的重要性。研究组推广了该方法，并展示了近十几种此前没有报道过的III-V族固溶体纳米晶成分。

▲ Abstract：

Colloidal quantum dots, with their size-tunable optoelectronic properties and scalable synthesis, enable applications in which inexpensive high-performance semiconductors are needed. Synthesis science breakthroughs have been key to the realization of quantum dot technologies, but important group III–group V semiconductors, including colloidal gallium arsenide (GaAs), still cannot be synthesized with existing approaches. The high-temperature molten salt colloidal synthesis introduced in this work enables the preparation of previously intractable colloidal materials. We directly nucleated and grew colloidal quantum dots in molten inorganic salts by harnessing molten salt redox chemistry and using surfactant additives for nanocrystal shape control. Synthesis temperatures above 425°C are critical for realizing photoluminescent GaAs quantum dots, which emphasizes the importance of high temperatures enabled by molten salt solvents. We generalize the methodology and demonstrate nearly a dozen III-V solid-solution nanocrystal compositions that have not been previously reported.

Topological grain boundary segregation transitions

拓扑晶界偏析相变

▲ 作者：VIVEK DEVULAPALLI, ENZE CHEN, TOBIAS BRINK, TIMOFEY FROLOV AND CHRISTIAN H. LIEBSCHER

▲链接：

https://www.science.org/doi/10.1126/science.adq4147

▲摘要：

利用溶质偏析技术设计晶界（GBs）结构是一种定制多晶材料性能的颇具前景的方法。从理论上讲，溶质偏析触发GB相变可为设计界面提供不同的途径，但缺乏对其本征原子性质的理解。

研究组结合了原子分辨率电子显微镜和原子模拟，发现钛中铁向GB的偏析稳定了二十面体单元（“笼”），形成了不同GB相的稳健构建块。由于其五重对称性，铁“笼”聚集并组装成具有不同数量和不同排列的二十面体单元构建块的分层GB相。

这种先进的GB结构预测算法和原子模拟验证了这些观察到的各相稳定性，以及相变所适应GB处铁的高过量。

▲ Abstract：

Engineering the structure of grain boundaries (GBs) by solute segregation is a promising strategy to tailor the properties of polycrystalline materials. Solute segregation triggering phase transitions at GBs has been suggested theoretically to offer different pathways to design interfaces, but an understanding of their intrinsic atomistic nature is missing. We combined atomic resolution electron microscopy and atomistic simulations to discover that iron segregation to GBs in titanium stabilizes icosahedral units (“cages”) that form robust building blocks of distinct GB phases. Owing to their five-fold symmetry, the iron cages cluster and assemble into hierarchical GB phases characterized by a different number and arrangement of the constituent icosahedral units. Our advanced GB structure prediction algorithms and atomistic simulations validate the stability of these observed phases and the high excess of iron at the GB that is accommodated by the phase transitions.

Soft hydrogel semiconductors with augmented biointeractive functions

软水凝胶半导体可增强生物交互功能

▲ 作者：YAHAO DAI, SHINYA WAI, PENGJU LI, NAISONG SHAN, ZHIQIANG CAO, YANG LI, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adp9314

▲摘要：

水凝胶因其与生物组织的机械和化学相似性而闻名，广泛应用于生物技术，而半导体则提供先进的电子和光电功能，如信号放大、传感和光调制。将半导体特性与水凝胶设计相结合可以增强生物界面处的生物交互功能和亲密性，但由于聚合物半导体的亲水性较低，这很难实现。

研究组开发了一种溶剂亲和诱导组装方法，将不溶于水的聚合物半导体结合到双网络水凝胶中。这些半导体表现出软至81千帕的组织级模量、150%应变的拉伸率、高达1.4平方厘米/伏/秒的载流子迁移率。当其与生物组织结合时，该组织级模量可减轻免疫反应。

水凝胶的高孔隙度增强了半导体-生物流体界面的分子相互作用，从而实现了具有更高响应的光调制和具有更高灵敏度的体积生物传感。

▲ Abstract：

Hydrogels, known for their mechanical and chemical similarity to biological tissues, are widely used in biotechnologies, whereas semiconductors provide advanced electronic and optoelectronic functionalities such as signal amplification, sensing, and photomodulation. Combining semiconducting properties with hydrogel designs can enhance biointeractive functions and intimacy at biointerfaces, but this is challenging owing to the low hydrophilicity of polymer semiconductors. We developed a solvent affinity–induced assembly method that incorporates water-insoluble polymer semiconductors into double-network hydrogels. These semiconductors exhibited tissue-level moduli as soft as 81 kilopascals, stretchability of 150% strain, and charge-carrier mobility up to 1.4 square centimeters per volt per second. When they are interfaced with biological tissues, their tissue-level modulus enables alleviated immune reactions. The hydrogel’s high porosity enhances molecular interactions at semiconductor-biofluid interfaces, resulting in photomodulation with higher response and volumetric biosensing with higher sensitivity.

能源科学Energy Science

Unification of insertion and supercapacitive storage concepts: Storage profiles in titania

插入式储能和超级电容储能概念的统一：二氧化钛中的储能概况

▲ 作者：CHUANLIAN XIAO, HONGGUANG WANG, ROBERT USISKIN, PETER A. VAN AKEN AND JOACHIM MAIER

▲链接：

https://www.science.org/doi/10.1126/science.adi5700

▲摘要：

电池电极中的插入式储能和超级电容储能通常被认为是两个独立的现象，因此由不同的科学界进行研究。

通过对不同厚度的氧化钛薄膜进行定制实验，研究组证明了这两个过程可同时发生。为了解释包含这两种贡献的整个存储分布，混合导体和邻近相中电荷载流子的（自由）能是唯一需要的材料参数。

实验结果实现了插入式储能和超级电容储能的统一，前者在厚膜中占主导地位，后者在薄膜或可忽略电子导电性的膜中占主导地位。因此，存储介质的尺寸和电流收集相的性质可用来调整功率密度与能量密度。

▲ Abstract：

Insertion storage in battery electrodes and supercapacitive storage are typically considered to be independent phenomena and thus are dealt with in separate scientific communities. Using tailored experiments on titanium oxide thin films of various thicknesses, we demonstrate the simultaneous occurrence of both processes. For the interpretation of the entire storage profile encompassing both contributions, the (free) energies of the charge carriers in the mixed conductor and the neighboring phase are the only materials parameters required. The experimental results enable no less than a unification of insertion and supercapacitive storage, the first being dominant for thick films, the latter for thin films or negligible electronic conductivity. Therefore, the size of the storage medium and the nature of the current collecting phases can be used to tune power density versus energy density.

地球科学Earth Science

The fastest-growing and most destructive fires in the US (2001 to 2020)

美国增长最快、最具破坏性的火灾（2001~2020年）

▲ 作者：JENNIFER K. BALCH, VIRGINIA IGLESIAS, ADAM L. MAHOOD, MAXWELL C. COOK, CIBELE AMARAL, AMY DECASTRO, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adk5737

▲摘要：

美国历史上最具破坏性、最致命的野火来势汹汹。

利用卫星数据，研究组分析了2001年至2020年美国本土6万多起火灾的日增长率。近一半的生态区经历了破坏性的快速火灾，大火在一天内蔓延了1620多公顷。这些火灾造成78%的建筑物被毁，占灭火费用的61%（189亿美元）。

从2001年到2020年，美国西部这些火灾的平均峰值日增长率翻了一倍多（相对于2001年增长249%）。在此期间，美国有近300万栋建筑物距离一场快速火灾不到4千米。鉴于最近毁灭性的野火，了解快速火灾对于改进消防策略和社区准备至关重要。

▲ Abstract：

The most destructive and deadly wildfires in US history were also fast. Using satellite data, we analyzed the daily growth rates of more than 60,000 fires from 2001 to 2020 across the contiguous US. Nearly half of the ecoregions experienced destructive fast fires that grew more than 1620 hectares in 1 day. These fires accounted for 78% of structures destroyed and 61% of suppression costs ($18.9 billion). From 2001 to 2020, the average peak daily growth rate for these fires more than doubled (+249% relative to 2001) in the Western US. Nearly 3 million structures were within 4 kilometers of a fast fire during this period across the US. Given recent devastating wildfires, understanding fast fires is crucial for improving firefighting strategies and community preparedness.

Twenty years of microplastic pollution research—what have we learned?

二十年的微塑料污染研究——我们学到了什么？

▲ 作者：RICHARD C. THOMPSON, WINNIE COURTENE-JONES, JULIEN BOUCHER, SABINE PAHL, KAREN RAUBENHEIMER AND ALBERT A. KOELMANS

▲链接：

https://www.science.org/doi/10.1126/science.adl2746

▲摘要：

在首次使用“微塑料”一词的出版物发表20年后，研究组回顾了当前的理解，完善了定义，并考虑了未来的前景。微塑料有多种来源，包括轮胎、纺织品、化妆品、油漆和大件物品的碎片，其广泛分布在整个自然环境中，有证据表明在生物组织的多个层面上都有危害。

微塑料在食物和饮料中普遍存在，已在人体中被检测到，并出现了负面影响的新证据。到2040年，环境污染可能会翻一番，预计会造成大规模的危害。公众的关注日益增加，国际谈判正在考虑解决微塑料污染的各种措施。

当前需要明确证据证明潜在解决办法的效力，以解决微塑料污染并尽量减少意外后果的风险。

▲ Abstract：

Twenty years after the first publication that used the term microplastic, we review current understanding, refine definitions, and consider future prospects. Microplastics arise from multiple sources, including tires, textiles, cosmetics, paint, and the fragmentation of larger items. They are widely distributed throughout the natural environment, with evidence of harm at multiple levels of biological organization. They are pervasive in food and drink and have been detected throughout the human body, with emerging evidence of negative effects. Environmental contamination could double by 2040, and wide-scale harm has been predicted. Public concern is increasing, and diverse measures to address microplastic pollution are being considered in international negotiations. Clear evidence on the efficacy of potential solutions is now needed to address the issue and to minimize the risks of unintended consequences.