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美国能源部投资1370万美元支持碳转化技术研发 快报文章
气候变化快报,2025年第3期
作者:  董利苹 杜海霞
Microsoft Word(17Kb)  |  收藏  |  浏览/下载:440/0  |  提交时间:2025/02/04
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Molecular tuning of CO2-to-ethylene conversion 期刊论文
NATURE, 2020, 577 (7791) : 509-+
作者:  Li, Fengwang;  39;Brien, Colin P.
收藏  |  浏览/下载:26/0  |  提交时间:2020/07/03

The electrocatalytic reduction of carbon dioxide, powered by renewable electricity, to produce valuable fuels and feedstocks provides a sustainable and carbon-neutral approach to the storage of energy produced by intermittent renewable sources(1). However, the highly selective generation of economically desirable products such as ethylene from the carbon dioxide reduction reaction (CO2RR) remains a challenge(2). Tuning the stabilities of intermediates to favour a desired reaction pathway can improve selectivity(3-5), and this has recently been explored for the reaction on copper by controlling morphology(6), grain boundaries(7), facets(8), oxidation state(9) and dopants(10). Unfortunately, the Faradaic efficiency for ethylene is still low in neutral media (60 per cent at a partial current density of 7 milliamperes per square centimetre in the best catalyst reported so far(9)), resulting in a low energy efficiency. Here we present a molecular tuning strategy-the functionalization of the surface of electrocatalysts with organic molecules-that stabilizes intermediates for more selective CO2RR to ethylene. Using electrochemical, operando/in situ spectroscopic and computational studies, we investigate the influence of a library of molecules, derived by electro-dimerization of arylpyridiniums(11), adsorbed on copper. We find that the adhered molecules improve the stabilization of an '  atop-bound'  CO intermediate (that is, an intermediate bound to a single copper atom), thereby favouring further reduction to ethylene. As a result of this strategy, we report the CO2RR to ethylene with a Faradaic efficiency of 72 per cent at a partial current density of 230 milliamperes per square centimetre in a liquid-electrolyte flow cell in a neutral medium. We report stable ethylene electrosynthesis for 190 hours in a system based on a membrane-electrode assembly that provides a full-cell energy efficiency of 20 per cent. We anticipate that this may be generalized to enable molecular strategies to complement heterogeneous catalysts by stabilizing intermediates through local molecular tuning.


Electrocatalytic reduction of CO2 over copper can be made highly selective by '  tuning'  the copper surface with adsorbed organic molecules to stabilize intermediates for carbon-based fuels such as ethylene


  
Accelerated discovery of CO2 electrocatalysts using active machine learning 期刊论文
NATURE, 2020, 581 (7807) : 178-+
作者:  Lan, Jun;  Ge, Jiwan;  Yu, Jinfang;  Shan, Sisi;  Zhou, Huan;  Fan, Shilong;  Zhang, Qi;  Shi, Xuanling;  Wang, Qisheng;  Zhang, Linqi;  Wang, Xinquan
收藏  |  浏览/下载:127/0  |  提交时间:2020/07/03

The rapid increase in global energy demand and the need to replace carbon dioxide (CO2)-emitting fossil fuels with renewable sources have driven interest in chemical storage of intermittent solar and wind energy(1,2). Particularly attractive is the electrochemical reduction of CO2 to chemical feedstocks, which uses both CO2 and renewable energy(3-8). Copper has been the predominant electrocatalyst for this reaction when aiming for more valuable multi-carbon products(9-16), and process improvements have been particularly notable when targeting ethylene. However, the energy efficiency and productivity (current density) achieved so far still fall below the values required to produce ethylene at cost-competitive prices. Here we describe Cu-Al electrocatalysts, identified using density functional theory calculations in combination with active machine learning, that efficiently reduce CO2 to ethylene with the highest Faradaic efficiency reported so far. This Faradaic efficiency of over 80 per cent (compared to about 66 per cent for pure Cu) is achieved at a current density of 400 milliamperes per square centimetre (at 1.5 volts versus a reversible hydrogen electrode) and a cathodic-side (half-cell) ethylene power conversion efficiency of 55 +/- 2 per cent at 150 milliamperes per square centimetre. We perform computational studies that suggest that the Cu-Al alloys provide multiple sites and surface orientations with near-optimal CO binding for both efficient and selective CO2 reduction(17). Furthermore, in situ X-ray absorption measurements reveal that Cu and Al enable a favourable Cu coordination environment that enhances C-C dimerization. These findings illustrate the value of computation and machine learning in guiding the experimental exploration of multi-metallic systems that go beyond the limitations of conventional single-metal electrocatalysts.


  
Lactonization as a general route to beta-C(sp(3))-H functionalization 期刊论文
NATURE, 2020, 577 (7792) : 656-+
作者:  Washington, Harriet A.
收藏  |  浏览/下载:27/0  |  提交时间:2020/07/03

Functionalization of the beta-C-H bonds of aliphatic acids is emerging as a valuable synthetic disconnection that complements a wide range of conjugate addition reactions(1-5). Despite efforts for beta-C-H functionalization in carbon-carbon and carbon-heteroatom bond-forming reactions, these have numerous crucial limitations, especially for industrial-scale applications, including lack of mono-selectivity, use of expensive oxidants and limited scope(6-13). Notably, the majority of these reactions are incompatible with free aliphatic acids without exogenous directing groups. Considering the challenge of developing C-H activation reactions, it is not surprising that achieving different transformations requires independent catalyst design and directing group optimizations in each case. Here we report a Pd-catalysed beta-C(sp(3))-H lactonization of aliphatic acids enabled by a mono-N-protected beta-amino acid ligand. The highly strained and reactive beta-lactone products are versatile linchpins for the mono-selective installation of diverse alkyl, alkenyl, aryl, alkynyl, fluoro, hydroxyl and amino groups at the beta position of the parent acid, thus providing a route to many carboxylic acids. The use of inexpensive tert-butyl hydrogen peroxide as the oxidant to promote the desired selective reductive elimination from the Pd(IV) centre, as well as the ease of product purification without column chromatography, render this reaction amenable to tonne-scale manufacturing.


  
Copper-mediated synthesis of drug-like bicyclopentanes 期刊论文
NATURE, 2020, 580 (7802) : 220-+
作者:  Canavelli, Pierre;  Islam, Saidul;  Powner, Matthew W.
收藏  |  浏览/下载:12/0  |  提交时间:2020/07/03

Multicomponent reactions are relied on in both academic and industrial synthetic organic chemistry owing to their step- and atom-economy advantages over traditional synthetic sequences(1). Recently, bicyclo[1.1.1]pentane (BCP) motifs have become valuable as pharmaceutical bioisosteres of benzene rings, and in particular 1,3-disubstituted BCP moieties have become widely adopted in medicinal chemistry as para-phenyl ring replacements(2). These structures are often generated from [1.1.1]propellane via opening of the internal C-C bond through the addition of either radicals or metal-based nucleophiles(3-13). The resulting propellane-addition adducts are then transformed to the requisite polysubstituted BCP compounds via a range of synthetic sequences that traditionally involve multiple chemical steps. Although this approach has been effective so far, a multicomponent reaction that enables single-step access to complex and diverse polysubstituted drug-like BCP products would be more time efficient compared to current stepwise approaches. Here we report a one-step three-component radical coupling of [1.1.1]propellane to afford diverse functionalized bicyclopentanes using various radical precursors and heteroatom nucleophiles via a metallaphotoredox catalysis protocol. This copper-mediated reaction operates on short timescales (five minutes to one hour) across multiple (more than ten) nucleophile classes and can accommodate a diverse array of radical precursors, including those that generate alkyl, alpha-acyl, trifluoromethyl and sulfonyl radicals. This method has been used to rapidly prepare BCP analogues of known pharmaceuticals, one of which is substantially more metabolically stable than its commercial progenitor.


A one-step, three-component radical coupling of [1.1.1]propellane by a photoredox reaction mediated by a copper catalyst produces drug-like bicyclopentanes.


  
Synthesis of rare sugar isomers through site-selective epimerization 期刊论文
NATURE, 2020: 403-+
作者:  Jackson, Hartland W.;  Fischer, Jana R.;  Zanotelli, Vito R. T.;  Ali, H. Raza;  Mechera, Robert;  Soysal, Savas D.;  Moch, Holger;  Muenst, Simone;  Varga, Zsuzsanna;  Weber, Walter P.;  Bodenmiller, Bernd
收藏  |  浏览/下载:24/0  |  提交时间:2020/07/03

Glycans have diverse physiological functions, ranging from energy storage and structural integrity to cell signalling and the regulation of intracellular processes(1). Although biomass-derived carbohydrates (such as d-glucose, d-xylose and d-galactose) are extracted on commercial scales, and serve as renewable chemical feedstocks and building blocks(2,3), there are hundreds of distinct monosaccharides that typically cannot be isolated from their natural sources and must instead be prepared through multistep chemical or enzymatic syntheses(4,5). These '  rare'  sugars feature prominently in bioactive natural products and pharmaceuticals, including antiviral, antibacterial, anticancer and cardiac drugs(6,7). Here we report the preparation of rare sugar isomers directly from biomass carbohydrates through site-selective epimerization reactions. Mechanistic studies establish that these reactions proceed under kinetic control, through sequential steps of hydrogen-atom abstraction and hydrogen-atom donation mediated by two distinct catalysts. This synthetic strategy provides concise and potentially extensive access to this valuable class of natural compounds.


Various rare sugars that cannot be isolated from natural sources are synthesized using light-driven epimerization, a process which may find application in other synthetic scenarios.