《自然》（20231130出版）一周論文導讀

原文地址：http://news.sciencenet.cn/htmlnews/2023/12/513489.shtm

編譯 | 未玖

Nature, 30 November 2023, VOL 623, ISSUE 7989

《自然》2023年11月30日，第623卷，7989期

物理學Physics

Imaging inter-valley coherent order in magic-angle twisted trilayer graphene

魔角扭曲三層石墨烯中的谷間相干序成像

▲ 作者：Hyunjin Kim, Youngjoon Choi, étienne Lantagne-Hurtubise, Cyprian Lewandowski, Alex Thomson, Lingyuan Kong, et al.

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06663-8

▲ 摘要：

魔角扭曲三層石墨烯（MATTG）表現出一系列自發打破潛在對稱性的強相關電子相。研究組使用掃描隧道顯微鏡研究了MATTG的相關相位，并確定了相互作用驅動的空間對稱性破缺的顯著特征。

低應變樣品中，在每個莫爾晶胞大約兩到三個電子或空穴的填充范圍內，研究觀察到石墨烯晶格的原子級重建，并伴隨著隧穿光譜中的相關能隙。這種短尺度的重組表現為一個凱庫勒超晶胞（意味著電子之間自發的谷間相干性），并在與能隙發展相一致的寬磁場和溫度范圍內持續存在。

覆蓋多個莫爾晶胞的大比例尺圖進一步揭示了凱庫勒模式的緩慢演變，表明原子尺度重建與更長莫爾尺度上的平移對稱性破缺共存。研究組使用自相關和傅立葉分析來提取這些相位的本征周期性，發現其與理論上不相稱的凱庫勒螺旋階一致。

此外還發現，表征莫爾尺度調制的波長隨著空穴摻雜遠離帶的半填充而單調減小，且對磁場的依賴性較弱。該研究結果為存在應變情況下MATTG相關相的性質提供了重要見解，并表明超導性可從谷間相干母態中出現。

▲ Abstract：

Magic-angle twisted trilayer graphene (MATTG) exhibits a range of strongly correlated electronic phases that spontaneously break its underlying symmetries. Here we investigate the correlated phases of MATTG using scanning tunnelling microscopy and identify marked signatures of interaction-driven spatial symmetry breaking. In low-strain samples, over a filling range of about two to three electrons or holes per moiré unit cell, we observe atomic-scale reconstruction of the graphene lattice that accompanies a correlated gap in the tunnelling spectrum. This short-scale restructuring appears as a Kekulé supercell—implying spontaneous inter-valley coherence between electrons—and persists in a wide range of magnetic fields and temperatures that coincide with the development of the gap. Large-scale maps covering several moiré unit cells further reveal a slow evolution of the Kekulé pattern, indicating that atomic-scale reconstruction coexists with translation symmetry breaking at a much longer moiré scale. We use auto-correlation and Fourier analyses to extract the intrinsic periodicity of these phases and find that they are consistent with the theoretically proposed incommensurate Kekulé spiral order. Moreover, we find that the wavelength characterizing moiré-scale modulations monotonically decreases with hole doping away from half-filling of the bands and depends weakly on the magnetic field. Our results provide essential insights into the nature of the correlated phases of MATTG in the presence of strain and indicate that superconductivity can emerge from an inter-valley coherent parent state.

材料科學Materials Science

A stable atmospheric-pressure plasma for extreme-temperature synthesis

用于極端溫度合成的穩定大氣壓等離子體

▲ 作者：Hua Xie, Ning Liu, Qian Zhang, Hongtao Zhong, Liqun Guo, Xinpeng Zhao, et al.

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06694-1

▲ 摘要：

等離子體能夠產生超高溫反應環境，可用于各種材料的合成和加工。然而，等離子體的體積有限、不穩定性和不均勻性使得大規模生產大塊高溫材料頗具挑戰性。

研究組提出了一種由一對碳纖維尖端增強電極組成的等離子體裝置，能夠在大氣壓下使用垂直取向的長、短碳纖維組合產生均勻、超高溫和穩定的等離子體（高達8000 K）。長碳纖維通過微火花放電在低擊穿電壓下引發等離子體，而短碳纖維將放電凝聚成體積大且穩定的超高溫等離子體。

作為概念驗證，研究組使用該工藝在幾秒鐘內合成了各種極端材料，包括超高溫陶瓷（例如碳氮化鉿）和難熔金屬合金。此外，碳氈電極柔韌性很高，可塑造為各種合成造型。這種簡單實用的等離子體技術或有助于克服高溫合成中的挑戰，并實現由可再生電力驅動的大規模電氣化等離子體制造。

▲ Abstract：

Plasmas can generate ultra-high-temperature reactive environments that can be used for the synthesis and processing of a wide range of materials. However, the limited volume, instability and non-uniformity of plasmas have made it challenging to scalably manufacture bulk, high-temperature materials. Here we present a plasma set-up consisting of a pair of carbon-fibre-tip-enhanced electrodes that enable the generation of a uniform, ultra-high temperature and stable plasma (up to 8,000?K) at atmospheric pressure using a combination of vertically oriented long and short carbon fibres. The long carbon fibres initiate the plasma by micro-spark discharge at a low breakdown voltage, whereas the short carbon fibres coalesce the discharge into a volumetric and stable ultra-high-temperature plasma. As a proof of concept, we used this process to synthesize various extreme materials in seconds, including ultra-high-temperature ceramics (for example, hafnium carbonitride) and refractory metal alloys. Moreover, the carbon-fibre electrodes are highly flexible and can be shaped for various syntheses. This simple and practical plasma technology may help overcome the challenges in high-temperature synthesis and enable large-scale electrified plasma manufacturing powered by renewable electricity.

化學Chemistry

Associative pyridinium electrolytes for air-tolerant redox flow batteries

締合吡啶鎓電解質助力耐空氣氧化還原液流電池

▲ 作者：Mark E. Carrington, Kamil Soko?owski, Erlendur Jónsson, Evan Wenbo Zhao, Anton M. Graf, Israel Temprano, et al.

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06664-7

▲ 摘要：

吡啶鎓電解質是基于液流電池儲能頗有潛力的候選材料。然而，人們對其充放電過程和整體循環穩定性的潛在機制知之甚少。

研究組探討了吡啶鎓電解質在代表性液流電池條件下的氧化還原行為，揭示了包含這些電解質電池的空氣耐受性，同時提供了其可逆性的通用物理化學描述符。利用擴展雙吡啶化合物的合成庫跟蹤吡啶鎓電解質在廣泛電位范圍內的性能，并將單線態—三線態自由能隙確定為成功預測先前未確定的容量衰減機制開始的描述符。

利用耦合原位核磁共振和電子順磁共振波譜，研究組解釋了這些電解質的氧化還原行為，并確定了存在電化學性能的兩種不同機制（窄能隙和寬能隙）。在這兩種機制中，他們將容量衰減與自由基物種的形成聯系起來，進一步表明π—二聚化在抑制自由基與微量雜質（如溶解氧）之間的反應性方面起決定性作用。

該研究結果與圍繞π—二聚體在氧化還原液流電池中作用的主流觀點形成了直接對比，且能夠有效地減輕氧氣導致的容量衰減，即使在長時間（數天）暴露于空氣中亦是如此。這些見解為新型電解質系統設計奠定了基礎，該系統中還原物種的反應性由其對分子內和分子間自由基配對的傾向控制，從而能夠在空氣中運行。

▲ Abstract：

Pyridinium electrolytes are promising candidates for flow-battery-based energy storage. However, the mechanisms underlying both their charge–discharge processes and overall cycling stability remain poorly understood. Here we probe the redox behaviour of pyridinium electrolytes under representative flow battery conditions, offering insights into air tolerance of batteries containing these electrolytes while providing a universal physico-chemical descriptor of their reversibility. Leveraging a synthetic library of extended bispyridinium compounds, we track their performance over a wide range of potentials and identify the singlet–triplet free energy gap as a descriptor that successfully predicts the onset of previously unidentified capacity fade mechanisms. Using coupled operando nuclear magnetic resonance and electron paramagnetic resonance spectroscopies, we explain the redox behaviour of these electrolytes and determine the presence of two distinct regimes (narrow and wide energy gaps) of electrochemical performance. In both regimes, we tie capacity fade to the formation of free radical species, and further show that π-dimerization plays a decisive role in suppressing reactivity between these radicals and trace impurities such as dissolved oxygen. Our findings stand in direct contrast to prevailing views surrounding the role of π-dimers in redox flow batteries and enable us to efficiently mitigate capacity fade from oxygen even on prolonged (days) exposure to air. These insights pave the way to new electrolyte systems, in which reactivity of reduced species is controlled by their propensity for intra- and intermolecular pairing of free radicals, enabling operation in air.

On-surface synthesis of a doubly anti-aromatic carbon allotrope

雙反芳香性碳同素異形體的表面合成

▲ 作者：Yueze Gao, Florian Albrecht, Igor Ron?evi?, Isaac Ettedgui, Paramveer Kumar, Lorel M. Scriven, et al.

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06566-8

▲ 摘要：

合成碳同素異形體（如石墨烯、碳納米管和富勒烯）已徹底改變了材料科學，并帶來了新技術。人們已討論了許多假設的碳同素異形體，但很少有實驗研究。最近，動態共價化學和表面合成等非常規合成策略已被用于創造新形式碳，包括γ—石墨炔、富勒烯聚合物、聯苯烯網絡和環碳。

環[N]碳是由N個碳原子組成的分子環；迄今為止已報道的三種（N = 10、14和18）都是雙芳香的，這就引發了一個問題：是否有可能制備雙反芳香的版本？研究組報道了一種通過尖端誘導的表面化學來合成和表征反芳香碳同素異形體環[16]碳的策略。

除了原子力顯微鏡的結構信息外，他們還通過掃描隧道顯微鏡記錄軌道密度圖來探測其電子結構。環[16]碳的鍵長交替觀察證實了其雙反芳香性，與理論一致。C16的簡單結構使其成為研究芳香性極限的有趣模型系統，其高反應性使其成為新型碳同素異形體頗有前景的前體。

▲ Abstract：

Synthetic carbon allotropes such as graphene, carbon nanotubes and fullerenes have revolutionized materials science and led to new technologies. Many hypothetical carbon allotropes have been discussed, but few have been studied experimentally. Recently, unconventional synthetic strategies such as dynamic covalent chemistry and on-surface synthesis have been used to create new forms of carbon, including γ-graphyne, fullerene polymers, biphenylene networks and cyclocarbons. Cyclo[N]carbons are molecular rings consisting of N carbon atoms; the three that have been reported to date (N?=?10, 14 and 18) are doubly aromatic, which prompts the question: is it possible to prepare doubly anti-aromatic versions? Here we report the synthesis and characterization of an anti-aromatic carbon allotrope, cyclo[16]carbon, by using tip-induced on-surface chemistry. In addition to structural information from atomic force microscopy, we probed its electronic structure by recording orbital density maps with scanning tunnelling microscopy. The observation of bond-length alternation in cyclo[16]carbon confirms its double anti-aromaticity, in concordance with theory. The simple structure of C16 renders it an interesting model system for studying the limits of aromaticity, and its high reactivity makes it a promising precursor to novel carbon allotropes.

信息科學Information Science

Remote collaboration fuses fewer breakthrough ideas

遠程協作融合更難產生突破性想法

▲ 作者：Yiling Lin, Carl Benedikt Frey & Lingfei Wu

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06767-1

▲ 摘要：

創新理論強調社會網絡和團隊作為突破性發現推動者的作用。今天，世界各地的科學家和發明家比以往任何時候都數量更多且相互聯系。然而，盡管越來越多的人有所發現，越來越多的想法能以新方式重新配置，但研究表明，新想法越來越難找到——這與重組增長理論相矛盾。

研究組解開了這個明顯的謎題。他們分析了過去半個世紀全球2000萬篇研究論文和400萬份專利申請，率先記錄了城市間遠程協作的興起，強調了全球科學家和發明家之間日益增長的相互聯系。結果進一步表明，在所有領域、時期和團隊規模中，這些遠程團隊的研究人員與他們的現場同行相比，始終不太可能取得突破性發現。

通過創建一個數據集來探索團隊內部和跨空間知識生產中的勞動分工，結果發現，在分布式團隊成員中，協作集中在涉及更多編碼知識的后期技術任務上。然而，當知識是隱性的時候，他們不太可能在概念性任務上聯合起來，比如構思新想法和設計研究。

研究組得出結論，盡管近年來數字技術取得了驚人的進步，但遠程團隊不太可能整合其成員的知識來產生新的、顛覆性的想法。

▲ Abstract：

Theories of innovation emphasize the role of social networks and teams as facilitators of breakthrough discoveries. Around the world, scientists and inventors are more plentiful and interconnected today than ever before. However, although there are more people making discoveries, and more ideas that can be reconfigured in new ways, research suggests that new ideas are getting harder to find—contradicting recombinant growth theory. Here we shed light on this apparent puzzle. Analysing 20 million research articles and 4 million patent applications from across the globe over the past half-century, we begin by documenting the rise of remote collaboration across cities, underlining the growing interconnectedness of scientists and inventors globally. We further show that across all fields, periods and team sizes, researchers in these remote teams are consistently less likely to make breakthrough discoveries relative to their on-site counterparts. Creating a dataset that allows us to explore the division of labour in knowledge production within teams and across space, we find that among distributed team members, collaboration centres on late-stage, technical tasks involving more codified knowledge. Yet they are less likely to join forces in conceptual tasks—such as conceiving new ideas and designing research—when knowledge is tacit. We conclude that despite striking improvements in digital technology in recent years, remote teams are less likely to integrate the knowledge of their members to produce new, disruptive ideas.

地球科學Earth Science

Ending extreme poverty has a negligible impact on global greenhouse gas emissions

消除極端貧困對全球溫室氣體排放的影響微乎其微

▲ 作者：Philip Wollburg, Stephane Hallegatte & Daniel Gerszon Mahler

▲ 鏈接：

https://www.nature.com/articles/s41586-023-06679-0

▲ 摘要：

不斷增長的消費既是結束極端貧困的必要條件，也是溫室氣體排放的主要驅動因素之一，這在脫貧和限制全球變暖之間造成了潛在的緊張關系。從歷史上看，大多數脫貧都因經濟增長而發生，這意味著脫貧不僅需要增加貧困人口的消費，還需要增加高收入人群的消費。

研究組使用每天2.15美元的國際貧困線來估算緩解極端貧困所需的經濟增長相關排放量。即使考慮到歷史上的能源強度和碳強度模式，與緩解極端貧困相關的全球排放量增長也不大，每年為23.7億噸二氧化碳當量，相當于2019年全球排放量的4.9%。

減少不平等、提高能源效率和能源脫碳可進一步緩解這種緊張關系：假設按照史上最好表現，2050年用于脫貧的排放量將減少90%。更雄心勃勃的貧困線要求更多國家實現更大的經濟增長，這將導致明顯更高的排放量。

研究結果表明，使世界發展目標和氣候目標保持一致的挑戰不在于調和極端脫貧與氣候目標，而在于提供可持續的中等收入生活水平。

▲ Abstract：