编译|未玖

Science,  12 JUL 2024, VOL 385, ISSUE 6705

《科学》2024年7月12日，第385卷，6705期

物理学Physics

Structured electrons with chiral mass and charge

具有手性质量和电荷的结构电子

▲ 作者：YIQI FANG, JOEL KUTTRUFF, DAVID NABBEN, AND PETER BAUM

▲链接：

https://www.science.org/doi/10.1126/science.adp9143

▲摘要：

手性是一种在基础物理学、材料科学、化学、光学和光谱学中具有广泛关联的现象。

这项工作中，研究组证明了自由电子可通过激光场周期转化为质量和电荷的右旋或左旋。与相位涡旋光束相比，该电子保持了平坦的德布罗意波，但从其时空期望值的形状获得了相应的手性。

通过阿秒门控测量波函数密度，揭示了具有左旋或右旋螺距的线圈和双线圈的三维形状。具有此类或相关手性几何结构的工程基本粒子可应用于手性传感、自由电子量子光学、粒子物理学或电子显微镜等领域。

▲ Abstract：

Chirality is a phenomenon with widespread relevance in fundamental physics, material science, chemistry, optics, and spectroscopy. In this work, we show that a free electron can be converted by the field cycles of laser light into a right-handed or left-handed coil of mass and charge. In contrast to phase-vortex beams, our electrons maintained a flat de Broglie wave but obtained their chirality from the shape of their expectation value in space and time. Measurements of wave function densities by attosecond gating revealed the three-dimensional shape of coils and double coils with left-handed or right-handed pitch. Engineered elementary particles with such or related chiral geometries should be useful for applications in chiral sensing, free-electron quantum optics, particle physics or electron microscopy.

材料科学Materials Science

A crystal capping layer for formation of black-phase FAPbI3 perovskite in humid air

在潮湿空气中形成黑相FAPbI3钙钛矿的晶体覆盖层

▲ 作者：YU ZOU, WENJIN YU, HAOQING GUO, QIZHI LI, XIANGDONG LI, LIANG LI, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adn9646

▲摘要：

黑相甲脒碘化铅（α-FAPbI3）钙钛矿是光伏应用的理想相，但水会引发诸如δ-FAPbI3光惰性杂质相的形成。

研究组表明，钙钛矿制造的经典溶剂系统加剧了这种可重复性挑战。传统配位溶剂二甲亚砜（DMSO）因其吸湿性，在高相对湿度（RH）条件下促进了δ-FAPbI3的形成。

研究组引入含氯有机分子来形成覆盖层，阻止水分渗透，同时保留基于DMSO的配合物来调节晶体生长。所得钙钛矿太阳能电池在20%至60% RH下的能量转换效率>24.5%，在80% RH下为23.4%。在最大功率点运行500小时后，未封装设备在空气中（40至60% RH）仍保留96%的初始性能。

▲ Abstract：

Black-phase formamidinium lead iodide (α-FAPbI3) perovskites are the desired phase for photovoltaic applications, but water can trigger formation of photoinactive impurity phases such as δ-FAPbI3. We show that the classic solvent system for perovskite fabrication exacerbates this reproducibility challenge. The conventional coordinative solvent dimethyl sulfoxide (DMSO) promoted δ-FAPbI3 formation under high relative humidity (RH) conditions because of its hygroscopic nature. We introduced chlorine-containing organic molecules to form a capping layer that blocked moisture penetration while preserving DMSO-based complexes to regulate crystal growth. We report power conversion efficiencies of >24.5% for perovskite solar cells fabricated across an RH range of 20 to 60%, and 23.4% at 80% RH. The unencapsulated device retained 96% of its initial performance in air (with 40 to 60% RH) after 500-hour maximum power point operation.

Partitioning polar-slush strategy in relaxors leads to large energy-storage capability

弛豫器的极性雪泥态区块化策略可实现大储能容量

▲ 作者：LIANG SHU, XIAOMING SHI, XIN ZHANG, ZIQI YANG, WEI LI, YUNPENG MA, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adn8721

▲摘要：

弛豫铁电（RFE）薄膜因其高能量密度（Ue）和高效率而成为小型化高功率电子系统颇有前景的储能候选材料。然而，将其Ue提高到200 J/cm3焦耳以上颇具挑战性，这限制了RFE在下一代储能设备中的应用潜力。

研究组在RFE中实施了一种极性雪泥态区块化策略来突破Ue的界限。在相场模拟的指导下，通过抑制非极性立方矩阵和引入高绝缘网络，设计并制备了具有隔离极性雪泥态团簇的Bi(Mg0.5Ti0.5)O3-SrTiO3基高性能RFE薄膜。

可逆极化和击穿强度的同时增强导致Ue达到202 J/cm3，效率高达79%。该策略为下一代高性能电介质提供了设计自由度。

▲ Abstract：

Relaxor ferroelectric (RFE) films are promising energy-storage candidates for miniaturizing high-power electronic systems, which is credited to their high energy density (Ue) and efficiency. However, advancing their Ue beyond 200 joules per cubic centimeter is challenging, limiting their potential for next-generation energy-storage devices. We implemented a partitioning polar-slush strategy in RFEs to push the boundary of Ue. Guided by phase-field simulations, we designed and fabricated high-performance Bi(Mg0.5Ti0.5)O3-SrTiO3–based RFE films with isolated slush-like polar clusters, which were realized through suppression of the nonpolar cubic matrix and introduction of highly insulating networks. The simultaneous enhancement of the reversible polarization and breakdown strength leads to a Ue of 202 joules per cubic centimeter with a high efficiency of ~79%. The proposed strategy provides a design freedom for next-generation high-performance dielectrics.

化学Chemistry

Resetting tropospheric OH and CH4 lifetime with ultraviolet H2O absorption

利用紫外水吸收重设对流层OH和CH4寿命

▲ 作者：MICHAEL J. PRATHER AND LEI ZHU

▲链接：

https://www.science.org/doi/10.1126/science.adn0415

▲摘要：

甲基氯仿（一种禁用的消耗臭氧物质）的衰变提供了对流层羟基自由基（OH）平均丰度的明确观测指标。几乎所有当前的全球化学模型都计算出约15%的OH过量，从而导致甲烷损失过快。甲烷是一种短暂的气候因子，对实现全球变暖目标至关重要，这一错误影响了人们对气候变化的模型预测。

研究组对紫外线区（290至350纳米）水汽吸收的新观测表明，近地表热带大气中的关键光解速率下降了8%至12%，导致阳光减少。化学输运模型中纳入这一新机制仅能减少4%的OH和甲烷损失，但结合其他提出的机制，如对流层卤素化学（7%），研究组有望解决这一难题。

▲ Abstract：

The decay of methyl chloroform, a banned ozone-depleting substance, has provided a clear observational metric of mean tropospheric hydroxyl radical (OH) abundance. Almost all current global chemistry models calculate about 15% too much OH and thus too rapid methane loss. Methane is a short-lived climate forcer, critical to achieving global warming targets, and this error affects our model projections of climate change. New observations of water vapor absorption in the ultraviolet region (290 to 350 nanometers) imply reductions in sunlight with key photolysis rates decreasing by 8 to 12% in the near-surface tropical atmosphere. Incorporation of this new mechanism in a chemistry-transport model reduces OH and methane loss by only 4%, but combined with other proposed mechanisms, such as tropospheric halogen chemistry (7%), we may be able to resolve this conundrum.

Programmed alternating current optimization of Cu-catalyzed C-H bond transformations

铜催化C-H键转化的可编程交流电优化

▲ 作者：LI ZENG, QINGHONG YANG, JIANXING WANG, XIN WANG, PENGJIE WANG, SHENGCHUN WANG, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.ado0875

▲摘要：

直流（DC）电合成技术在过去一个世纪里经历了不断的优化，在各种工业工艺中起着举足轻重的作用。交流（AC）电合成具有极性反转和周期性波动的特征，或有利于多种化学反应，但设备、原理和应用场景进展较慢。

在这项工作中，研究组介绍了一种可编程交流（pAC）电合成协议，可系统地调整电流、频率和占空比。代表性pAC波形的应用促进了在DC和化学氧化条件下表现不佳的交叉偶联和双官能化反应中的铜催化碳-氢键裂解。

此外，观察不同波形应用下的催化剂动态变化为人们提供了机理见解。

▲ Abstract：

Direct current (DC) electrosynthesis, which has undergone optimization over the past century, plays a pivotal role in a variety of industrial processes. Alternating current (AC) electrosynthesis, characterized by polarity reversal and periodic fluctuations, may be advantageous for multiple chemical reactions, but apparatus, principles, and application scenarios remain underdeveloped. In this work, we introduce a protocol for programmed AC (pAC) electrosynthesis that systematically adjusts currents, frequencies, and duty ratios. The application of representative pAC waveforms facilitates copper-catalyzed carbon-hydrogen bond cleavage in cross-coupling and difunctionalization reactions that exhibit suboptimal performance under DC and chemical oxidation conditions. Moreover, observing catalyst dynamic variation under diverse waveform applications provides mechanistic insight.

地球科学Earth Science

Stratospheric air intrusions promote global-scale new particle formation

平流层空气流入促进全球尺度新粒子的形成

▲ 作者：JIAOSHI ZHANG, XIANDA GONG, EWAN CROSBIE, GLENN DISKIN, KARL FROYD, SAMUEL HALL, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adn2961

▲摘要：

自由对流层中新粒子的形成是全球云凝结核的主要来源。主流观点认为，在自由对流层中，新粒子主要在对流云外流中形成。

研究组利用全球观测提出了另一种机制。结果发现，在平流层空气流入事件中，下降且富含臭氧的平流层空气与更湿润的自由对流层背景混合导致羟基自由基（OH）浓度升高。

这种混合在对流层顶附近最为普遍，那里二氧化硫（SO2）的混合比率较高。SO2和OH水平共同升高导致硫酸浓度升高，促进颗粒形成。这种新粒子的形成频率高，地理分布范围广，是中纬度自由对流层的重要粒子来源。

▲ Abstract：

New particle formation in the free troposphere is a major source of cloud condensation nuclei globally. The prevailing view is that in the free troposphere, new particles are formed predominantly in convective cloud outflows. We present another mechanism using global observations. We find that during stratospheric air intrusion events, the mixing of descending ozone-rich stratospheric air with more moist free tropospheric background results in elevated hydroxyl radical (OH) concentrations. Such mixing is most prevalent near the tropopause where the sulfur dioxide (SO2) mixing ratios are high. The combination of elevated SO2 and OH levels leads to enhanced sulfuric acid concentrations, promoting particle formation. Such new particle formation occurs frequently and over large geographic regions, representing an important particle source in the midlatitude free troposphere.