“激发态”《科学》（20240216出版）一周论文导读

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编译 | 未玖

Science, 16 FEB 2024, VOL 383, ISSUE 6684

《科学》2024年2月16日，第383卷，6684期

材料科学Materials Science

Superionic lithium transport via multiple coordination environments defined by two-anion packing

由双阴离子堆积定义的多配位环境下超离子锂输运

▲ 作者：Guopeng Han, Andrij Vasylenko, Luke M. Daniels, Chris M. Collins, Lucia Corti, Ruiyong Chen, et al.

▲ 链接：

https://www.science.org/doi/10.1126/science.adh5115

▲ 摘要：

固体材料中的快速阳离子输运是能量储存的基础。材料设计专注于能以最小阳离子配位变化定义运输途径的结构，因而将注意力限制在化学空间的一小部分。

受二元金属间化合物比金属元素更大的结构多样性所启发，研究组使用两种阴离子构建了利用多阳离子配位环境的三维超离子锂离子传导途径。Li7Si2S7I是一种纯锂离子导体，由硫化物和碘化物的有序化产生，其结合了类似于NiZr结构的六方和立方密排元素。

由此产生的具有不同几何结构和阴离子配位化学性质的不同锂位置网络提供了低运输势垒，为高阳离子电导率打开了较大的结构空间。

▲ 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

水诱导强各向同性Mxene交联石墨烯片助力电化学储能

▲ 作者：Jiao Yang, Mingzhu Li, Shaoli Fang, Yanlei Wang, Hongyan He, Chenlu Wang, et al.

▲ 链接：

https://www.science.org/doi/10.1126/science.adj3549

▲ 摘要：

石墨烯和二维过渡金属碳化物和/或氮化物（MXenes）因其电学和机械性能是制造柔性储能装置的重要材料。在室温下将这些材料的纳米片组装成面内各向同性、自支撑片层仍颇具挑战。

利用纳米限域水诱导的基面取向以及共价和π—π片间交联，研究组在室温下制备了Ti3C2Tx Mxene交联的石墨烯片，其各向同性面内抗拉强度为1.87 GPa，模量为98.7 GPa。面内室温电导率达到1423 S/cm，体积比容量达到828 C/cm3。

这种纳米限域水诱导取向有望助力其他二维纳米片的定向宏观组装。

▲ 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.

化学Chemistry

Roaming in highly excited states: The central atom elimination of triatomic molecule decomposition

高激发态下漫游反应：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.

▲ 链接：

https://www.science.org/doi/10.1126/science.adn3357

▲ 摘要：

人们通常认为化学反应沿着最小能量路径（MEP）从反应物转化为生成物。然而，偏离MEP（漫游反应）已被认为是一种非常规的反应机制，且在基态和第一激发态都观测到漫游反应的发生。然而，高激发态中是否存在漫游反应尚不明确。

研究组报道了一种在高激发态下由SO2光解产生电子激发片段S(1D) + O2(a1Δg)的解离通道。结果揭示了两种解离途径：一种是通过MEP产生振动较冷的O2(a1Δg)，另一种是在重定向运动过程中，通过涉及分子内O抽取的漫游途径产生振动较热的O2(a1Δg)。

这种漫游动力学很可能是通过高激发态进行分子光解的规则，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

利用熔点降低加速油水界面光化学反应

▲ 作者：Ya-Ming Tian, Wagner Silva, Ruth M. Gschwind & Burkhard Knig

▲ 链接：

https://www.science.org/doi/10.1126/science.adl3092

▲ 摘要：

水可以加速各种有机反应，远远超过在经典有机溶剂中观察到的速率。然而，使用纯水作为溶剂引入了溶解度限制，特别是限制了高效光化学的适用性。

研究组报道了在水介质中具有不同电子亲和力的芳烃、杂芳烃、烯胺或酯对之间形成聚集体，通过底物熔点降低生成油水相边界。反应物中的活性氢原子与水形成氢键，从而加速光化学反应。

该方法实现了复杂固体分子（包括难溶于水的复杂药物分子）水性偶联反应颇具吸引力的简单条件。

▲ 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

电驱动质子转移助力Br?nsted酸催化速率提升多个数量级

▲ 作者：Karl S. Westendorff, Max J. Hülsey, Thejas S. Wesley, Yuriy Román-Leshkov & Yogesh Surendranath

▲ 链接：

https://www.science.org/doi/10.1126/science.adk4902

▲ 摘要：

电场在酶催化中起着关键作用，可将反应速率提高10万倍，但在热化学非均相催化中尚未实现相同的速率提升。

研究组探讨了催化剂电势和界面电场对非均相Br?nsted酸催化的影响。结果观察到约380 mV的外加电位变化导致碳载磷钨酸催化1—甲基环戊醇脱水的速率提高10万倍。机理研究支持一种在限速C—O键裂解之前，界面静电势降驱动准平衡质子转移至吸附底物的模型。

在用Ti/TiOyHx催化的相同反应，以及用碳载磷钨酸催化苯甲醚与乙酸酐的Friedel—Crafts酰化反应中，研究组也观察到速率随电势的大幅增加。

▲ 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.

地球科学Earth Science

Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum

古新世-始新世热盛期热带上层海洋氧含量上升

▲ 作者：Simone Moretti, Alexandra Auderset, Curtis Deutsch, Ronja Schmitz, Lukas Gerber, Ellen Thomas, et al.

▲ 链接：

https://www.science.org/doi/10.1126/science.adh4893

▲ 摘要：

由于全球变暖，全球海洋的氧气储量正在下降，但低氧热带地区的未来仍不确定。

研究组报道了古新世—始新世热盛期（PETM）热带氧合作用的新证据，这是一个与人为变暖地质学上类似的变暖事件。有孔虫结合的氮同位素表明，热带北太平洋缺氧带在PETM期间收缩。

有孔虫尺寸的伴随增加意味着整个热带北太平洋浅层地下的氧气供应量增加。这些变化与海洋模型对变暖的模拟是一致的，即使全球海洋氧气量下降，但生物生产力的下降却使热带地下氧气增加。 热带氧气的增加或有助于避免PETM期间的大灭绝。

▲ 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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