編譯 | 未玖
Science, 16 FEB 2024, VOL 383, ISSUE 6684
《科學》2024年2月16日，第383卷，6684期
材料科學Materials Science
Superionic lithium transport via multiple coordination environments defined by two-anion packing
由雙陰離子堆積定義的多配位環境下超離子鋰輸運
▲ 作者：Guopeng Han, Andrij Vasylenko, Luke M. Daniels, Chris M. Collins, Lucia Corti, Ruiyong Chen, et al.
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adh5115
▲ 摘要：
固體材料中的快速陽離子輸運是能量儲存的基礎。材料設計專注于能以最小陽離子配位變化定義運輸途徑的結構，因而將注意力限制在化學空間的一小部分。
受二元金屬間化合物比金屬元素更大的結構多樣性所啟發，研究組使用兩種陰離子構建了利用多陽離子配位環境的三維超離子鋰離子傳導途徑。Li7Si2S7I是一種純鋰離子導體，由硫化物和碘化物的有序化產生，其結合了類似于NiZr結構的六方和立方密排元素。
由此產生的具有不同幾何結構和陰離子配位化學性質的不同鋰位置網絡提供了低運輸勢壘，為高陽離子電導率打開了較大的結構空間。
▲ Abstract：
Fast cation transport in solids underpins energy storage. Materials design has focused on structures that can define transport pathways with minimal cation coordination change, restricting attention to a small part of chemical space. Motivated by the greater structural diversity of binary intermetallics than that of the metallic elements, we used two anions to build a pathway for three-dimensional superionic lithium ion conductivity that exploits multiple cation coordination environments. Li7Si2S7I is a pure lithium ion conductor created by an ordering of sulphide and iodide that combines elements of hexagonal and cubic close-packing analogously to the structure of NiZr. The resulting diverse network of lithium positions with distinct geometries and anion coordination chemistries affords low barriers to transport, opening a large structural space for high cation conductivity.
Water-induced strong isotropic MXene-bridged graphene sheets for electrochemical energy storage
水誘導強各向同性Mxene交聯石墨烯片助力電化學儲能
▲ 作者：Jiao Yang, Mingzhu Li, Shaoli Fang, Yanlei Wang, Hongyan He, Chenlu Wang, et al.
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adj3549
▲ 摘要：
石墨烯和二維過渡金屬碳化物和/或氮化物（MXenes）因其電學和機械性能是制造柔性儲能裝置的重要材料。在室溫下將這些材料的納米片組裝成面內各向同性、自支撐片層仍頗具挑戰。
利用納米限域水誘導的基面取向以及共價和π—π片間交聯，研究組在室溫下制備了Ti3C2Tx Mxene交聯的石墨烯片，其各向同性面內抗拉強度為1.87 GPa，模量為98.7 GPa。面內室溫電導率達到1423 S/cm，體積比容量達到828 C/cm3。
這種納米限域水誘導取向有望助力其他二維納米片的定向宏觀組裝。
▲ Abstract：
Graphene and two-dimensional transition metal carbides and/or nitrides (MXenes) are important materials for making flexible energy storage devices because of their electrical and mechanical properties. It remains a challenge to assemble nanoplatelets of these materials at room temperature into in-plane isotropic, free-standing sheets. Using nanoconfined water-induced basal-plane alignment and covalent and π-π interplatelet bridging, we fabricated Ti3C2Tx MXene-bridged graphene sheets at room temperature with isotropic in-plane tensile strength of 1.87 gigapascals and moduli of 98.7 gigapascals. The in-plane room temperature electrical conductivity reached 1423 siemens per centimeter, and volumetric specific capacity reached 828 coulombs per cubic centimeter. This nanoconfined water-induced alignment likely provides an important approach for making other aligned macroscopic assemblies of two-dimensional nanoplatelets.
化學Chemistry
Roaming in highly excited states: The central atom elimination of triatomic molecule decomposition
高激發態下漫游反應：三原子分子分解的中心原子消除
▲ 作者：Zhenxing Li, Yan-lin Fu, Zijie Luo, Shuaikang Yang, Yucheng Wu, Hao Wu, et al.
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adn3357
▲ 摘要：
人們通常認為化學反應沿著最小能量路徑（MEP）從反應物轉化為生成物。然而，偏離MEP（漫游反應）已被認為是一種非常規的反應機制，且在基態和第一激發態都觀測到漫游反應的發生。然而，高激發態中是否存在漫游反應尚不明確。
研究組報道了一種在高激發態下由SO2光解產生電子激發片段S(1D) + O2(a1Δg)的解離通道。結果揭示了兩種解離途徑：一種是通過MEP產生振動較冷的O2(a1Δg)，另一種是在重定向運動過程中，通過涉及分子內O抽取的漫游途徑產生振動較熱的O2(a1Δg)。
這種漫游動力學很可能是通過高激發態進行分子光解的規則，而非例外。
▲ Abstract：
Chemical reactions are generally assumed to proceed from reactants to products along the minimum energy path (MEP). However, straying from the MEP—roaming—has been recognized as an unconventional reaction mechanism and found to occur in both the ground and first excited states. Its existence in highly excited states is however not yet established. We report a dissociation channel to produce electronically excited fragments, S(1D)+O2(a1Δg), from SO2 photodissociation in highly excited states. The results revealed two dissociation pathways: One proceeds through the MEP to produce vibrationally colder O2(a1Δg) and the other yields vibrationally hotter O2(a1Δg) by means of a roaming pathway involving an intramolecular O abstraction during reorientation motion. Such roaming dynamics may well be the rule rather than the exception for molecular photodissociation through highly excited states.
Accelerated photochemical reactions at oil-water interface exploiting melting point depression
利用熔點降低加速油水界面光化學反應
▲ 作者：Ya-Ming Tian, Wagner Silva, Ruth M. Gschwind & Burkhard Knig
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adl3092
▲ 摘要：
水可以加速各種有機反應，遠遠超過在經典有機溶劑中觀察到的速率。然而，使用純水作為溶劑引入了溶解度限制，特別是限制了高效光化學的適用性。
研究組報道了在水介質中具有不同電子親和力的芳烴、雜芳烴、烯胺或酯對之間形成聚集體，通過底物熔點降低生成油水相邊界。反應物中的活性氫原子與水形成氫鍵，從而加速光化學反應。
該方法實現了復雜固體分子（包括難溶于水的復雜藥物分子）水性偶聯反應頗具吸引力的簡單條件。
▲ Abstract：
Water can accelerate a variety of organic reactions far beyond the rates observed in classical organic solvents. However, using pure water as a solvent introduces solubility constraints that have limited the applicability of efficient photochemistry in particular. We report here the formation of aggregates between pairs of arenes, heteroarenes, enamines, or esters with different electron affinities in an aqueous medium, leading to an oil-water phase boundary through substrate melting point depression. The active hydrogen atoms in the reactants engage in hydrogen bonds with water, thereby accelerating photochemical reactions. This methodology realizes appealingly simple conditions for aqueous coupling reactions of complex solid molecules, including complex drug molecules that are poorly soluble in water.
Electrically driven proton transfer promotes Br?nsted acid catalysis by orders of magnitude
電驅動質子轉移助力Br?nsted酸催化速率提升多個數量級
▲ 作者：Karl S. Westendorff, Max J. Hülsey, Thejas S. Wesley, Yuriy Román-Leshkov & Yogesh Surendranath
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adk4902
▲ 摘要：
電場在酶催化中起著關鍵作用，可將反應速率提高10萬倍，但在熱化學非均相催化中尚未實現相同的速率提升。
研究組探討了催化劑電勢和界面電場對非均相Br?nsted酸催化的影響。結果觀察到約380 mV的外加電位變化導致碳載磷鎢酸催化1—甲基環戊醇脫水的速率提高10萬倍。機理研究支持一種在限速C—O鍵裂解之前，界面靜電勢降驅動準平衡質子轉移至吸附底物的模型。
在用Ti/TiOyHx催化的相同反應，以及用碳載磷鎢酸催化苯甲醚與乙酸酐的Friedel—Crafts酰化反應中，研究組也觀察到速率隨電勢的大幅增加。
▲ Abstract：
Electric fields play a key role in enzymatic catalysis and can enhance reaction rates by 100,000-fold, but the same rate enhancements have yet to be achieved in thermochemical heterogeneous catalysis. In this work, we probe the influence of catalyst potential and interfacial electric fields on heterogeneous Br?nsted acid catalysis. We observed that variations in applied potential of ~380 mV led to a 100,000-fold rate enhancement for 1-methylcyclopentanol dehydration, which was catalyzed by carbon-supported phosphotungstic acid. Mechanistic studies support a model in which the interfacial electrostatic potential drop drives quasi-equilibrated proton transfer to the adsorbed substrate prior to rate-limiting C–O bond cleavage. Large increases in rate with potential were also observed for the same reaction catalyzed by Ti/TiOyHx and for the Friedel Crafts acylation of anisole with acetic anhydride by carbon-supported phosphotungstic acid.
地球科學Earth Science
Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum
古新世-始新世熱盛期熱帶上層海洋氧含量上升
▲ 作者：Simone Moretti, Alexandra Auderset, Curtis Deutsch, Ronja Schmitz, Lukas Gerber, Ellen Thomas, et al.
▲ 鏈接：
https://www.science.org/doi/10.1126/science.adh4893
▲ 摘要：
由于全球變暖，全球海洋的氧氣儲量正在下降，但低氧熱帶地區的未來仍不確定。
研究組報道了古新世—始新世熱盛期（PETM）熱帶氧合作用的新證據，這是一個與人為變暖地質學上類似的變暖事件。有孔蟲結合的氮同位素表明，熱帶北太平洋缺氧帶在PETM期間收縮。
有孔蟲尺寸的伴隨增加意味著整個熱帶北太平洋淺層地下的氧氣供應量增加。這些變化與海洋模型對變暖的模擬是一致的，即使全球海洋氧氣量下降，但生物生產力的下降卻使熱帶地下氧氣增加。 熱帶氧氣的增加或有助于避免PETM期間的大滅絕。
▲ Abstract：
The global ocean’s oxygen inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We report new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analog to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM.
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