Chem 化学

Article 品

Electrochemical synthesis of formamide by CN coupling with amine and ${CO}_{2}$ with a high faradaic efficiency of 37.5%
CN 与胺偶联电化学合成甲酰胺， ${CO}_{2}$ 法拉第效率高达 37.5%

The strategy of synthesizing carbon dioxide and dimethylamine into dimethylformamide by electrocatalysis is realized. Through the optimization of the catalyst, the maximum faradaic efficiency and yield of dimethylformamide reached

37.5 %

and

385 mmol \cdot h^{- 1} \cdot g_{cat} \cdot^{- 1}

, respectively. It provides a strategy for the electrochemical

C - N

coupling of organic amines via carbon dioxide and is expected to be extended to synthesizing other amides.
实现了通过电催化将二氧化碳和二甲胺合成成二甲基甲酰胺的策略。通过催化剂的优化，二甲基甲酰胺的最大法拉第效率和收率分别达到

37.5 %

和

385 mmol \cdot h^{- 1} \cdot g_{cat} \cdot^{- 1}

。它为有机胺通过二氧化碳的电化学

C - N

偶联提供了一种策略，并有望扩展到合成其他酰胺。

Yun Fan, Tianyang Liu, Yunhui Yan, …, Yafei Li, Shuangyin Wang, Yuqin Zou
樊云，刘天阳，闫云辉， ...，李亚飞，王双银，邹玉琴
yuqin_zou@hnu.edu.cn

Highlights 突出

The electrosynthesis of dimethylformamide with

{CO}_{2}

and dimethylamine was achieved
实现了二甲基甲酰胺与

{CO}_{2}

和二甲胺的电合成

The catalytic mechanism between noble metal loading and metal defects is clarified
阐明贵金属负载与金属缺陷之间的催化机制

The electrochemical C-N coupling mechanism is confirmed
证实电化学 C-N 耦合机制

The synthesis of high-value organic nitrogen compounds from

{CO}_{2}

is proposed
提出了高值有机氮化合物的

{CO}_{2}

合成方法

Fan et al., Chem 10, 2437-2449
Fan 等人，化学 10,2437-2449
August 8, 2024 © 2024 Elsevier Inc. All rights reserved.
August 8， 2024 © 2024 爱思唯尔公司保留所有权利。
https://doi.org/10.1016/j.chempr.2024.03.024

Article 品

Electrochemical synthesis of formamide by $C - N$ coupling with amine and ${CO}_{2}$ with a high faradaic efficiency of $37.5 %$
通过与 $C - N$ 胺偶联电化学合成甲酰胺， ${CO}_{2}$ 法拉第效率高 $37.5 %$

Yun Fan, $^{1, 5}$ Tianyang Liu, $^{2, 5}$ Yunhui Yan, $^{1, 5}$ Zhongcheng Xia, $^{1}$ Yuxuan Lu, $^{1}$ Yuping Pan, $^{1}$ Ruiqi Wang, $^{1}$ Dianke Xie, $^{1}$ Zhonghuan Zhu, $^{1}$ Ta Thi Thuy Nga, $^{4}$ Chung-Li Dong, $^{4}$ Yu Jing, $^{2}$ Yafei Li, $^{3}$ Shuangyin Wang, $^{1}$ and Yuqin Zou $^{1, 6, *}$
樊云、 $^{1, 5}$ 刘天阳、 $^{2, 5}$ 闫云辉、 $^{1, 5}$ 夏忠成、 $^{1}$ 卢玉轩、 $^{1}$ 潘玉萍、 $^{1}$ 王瑞琪、 $^{1}$ 谢殿科、 $^{1}$ 朱忠欢、 $^{1}$ Ta Thi Thuy Nga、 $^{4}$ 董忠丽、 $^{4}$ 靖宇、 $^{2}$ 李亚飞、 $^{3}$ 王双茵 $^{1}$ 和邹 $^{1, 6, *}$ 玉琴

Abstract 抽象

SUMMARY N,N-Dimethylformamide (DMF) is a versatile chemical and universal solvent that is commonly synthesized from carbon monoxide and dimethylamine (DMA) under high temperature and pressure. However, this process leads to a large amount of carbon emissions. Herein, we propose an electrochemical strategy to directly convert carbon dioxide ( ${CO}_{2}$ ) and DMA to DMF under ambient conditions. Loading palladium (Pd) onto copper ( Cu ) nanosheet catalysts with Cu vacancies ( $Pd / {Cu}^{-} V_{Cu}$ ) enabled the efficient synthesis of DMF, and the maximum yield and faradaic efficiency reached $385 mmol \cdot h^{- 1} \cdot g_{cat}^{- 1}$ and $37.5 %$ , respectively. In situ spectroscopy and density functional theory calculations indicated that Cu vacancies ( $Cu - V_{Cu}$ ) promoted the adsorption of ${CO}_{2}$ on the catalyst surface, followed by its spontaneous coupling with DMA to form the $C - N$ bond. Pd nanoparticles accelerated the electrochemical reduction of the intermediate * $OCN {({CH}_{3})}_{2} OH$ to * $OCHN {({CH}_{3})}_{2} OH$ , leading to highly efficient DMF electrosynthesis. This work paves the way for the synthesis of sustainable high-value organic nitrogen compounds from ${CO}_{2}$ .
总结 N，N-二甲基甲酰胺（DMF）是一种用途广泛的化学通用溶剂，通常由一氧化碳和二甲胺（DMA）在高温高压下合成。然而，这个过程会导致大量的碳排放。在此，我们提出了一种在环境条件下直接将二氧化碳（ ${CO}_{2}$ ）和 DMA 转化为 DMF 的电化学策略。将钯（Pd）负载到具有 Cu 空位（ $Pd / {Cu}^{-} V_{Cu}$ ）的铜（Cu）纳米片催化剂上，可以高效合成 DMF，并分别达到 $385 mmol \cdot h^{- 1} \cdot g_{cat}^{- 1}$ $37.5 %$ 最大产率和法拉第效率。原位光谱和密度泛函理论计算表明，Cu 空位（ $Cu - V_{Cu}$ ）促进了催化剂表面 ${CO}_{2}$ 的吸附，随后与 DMA 自发偶联形成 $C - N$ 键。Pd 纳米颗粒加速了中间体* $OCN {({CH}_{3})}_{2} OH$ 到* $OCHN {({CH}_{3})}_{2} OH$ 的电化学还原，从而实现了高效的 DMF 电合成。这项工作为合成可持续的高价值有机氮化合物铺平了道路 ${CO}_{2}$ 。

INTRODUCTION 介绍

The sustainable synthesis of value-added chemicals from carbon dioxide (

{CO}_{2}

) molecules is a promising chemical strategy for producing fuel and other useful chemicals and converting carbon emissions.

^{1, 2}

Moreover, conducting such decarbonization tasks by using renewable energy sources, further reduces

{CO}_{2}

emissions. Present studies have focused on the conversion of

{CO}_{2}

into single-carbon (

C_{1}

) and multi-carbon (

C_{2 +}

) products, such as carbon monoxide ( CO ), formic acid ( HCOOH ), methanol

({CH}_{3} OH)

, acetic acid

({CH}_{3} COOH)

, ethylene

(C_{2} H_{4})

, ethanol

(C_{2} H_{5} OH)

, and so on.

^{3 - 9}

However, very limited products can be constructed in this manner with only

{CO}_{2}

and

H_{2} O

as the reactants. Therefore, the range of

{CO}_{2}

electroreduction products needs to be expanded urgently to meet the huge market demand.
从二氧化碳（

{CO}_{2}

）分子可持续合成增值化学品是生产燃料和其他有用化学品以及转化碳排放的一种有前途的化学策略。

^{1, 2}

此外，通过使用可再生能源进行此类脱碳任务，可以进一步减少

{CO}_{2}

排放。目前的研究主要集中在转化

{CO}_{2}

为单碳（

C_{1}

）和多碳（

C_{2 +}

）产物，如一氧化碳（CO）、甲酸（HCOOH）、甲醇

({CH}_{3} OH)

、乙酸

({CH}_{3} COOH)

、乙烯

(C_{2} H_{4})

、乙醇

(C_{2} H_{5} OH)

等。

^{3 - 9}

然而，仅以

{CO}_{2}

和

H_{2} O

作为反应物以这种方式构建的产物非常有限。因此，

{CO}_{2}

电还原产品的范围亟待扩大，以满足巨大的市场需求。

Organic nitrogen ( N ) compounds are widely used in pesticides, plastics, and polymers.

^{10}

In recent decades, the conversion of N - and C -containing small molecules into organic N compounds has received increasing attention. The synthesis of urea from

N_{2}

and

{CO}_{2}

by electrocatalysis is a mild and efficient

C - N

coupling process.

^{11}

Among them, amides are very important compounds in chemistry and biology. Especially, formamide

({CH}_{3} NO)

, the most basic amide, is the main raw
有机氮（N）化合物广泛用于农药、塑料和聚合物中。近几十年

^{10}

来，将含氮和含碳的小分子转化为有机氮化合物受到越来越多的关注。通过电催化合成

N_{2}

{CO}_{2}

尿素是一种温和而有效的

C - N

偶联过程。

^{11}

其中，酰胺是化学和生物学中非常重要的化合物。尤其是最碱性的酰胺

({CH}_{3} NO)

甲酰胺，是主要的原料

THE BIGGER PICTURE 更大的图景

N,N-Dimethylformamide (DMF) is a versatile chemical solvent commonly synthesized from carbon monoxide and dimethylamine (DMA) under high temperatures and pressure. However, this process leads to problems with carbon emissions. Herein, we propose an electrochemical strategy to convert carbon dioxide (

{CO}_{2}

) and DMA to DMF directly under ambient conditions. Loading palladium (Pd) onto copper (Cu) nanosheet catalysts with Cu vacancies enables the efficient synthesis of DMF; the maximum yield and faradaic efficiency can reach

385 mmol \cdot h^{- 1} \cdot g_{cat} .^{- 1}

and

37.5 %

, respectively. In situ characterizations and theoretical calculations indicate that Cu vacancies promote the adsorption of

{CO}_{2}

on the catalyst surface, followed by its spontaneous coupling with DMA. Pd nanoparticles accelerate the electrochemical reduction of the intermediate *

OCN {({CH}_{3})}_{2} OH

, leading to highly efficient DMF electrosynthesis. This work guides the synthesis of high-value organic nitrogen compounds from

{CO}_{2}

.
N，N-二甲基甲酰胺（DMF）是一种多功能化学溶剂，通常由一氧化碳和二甲胺（DMA）在高温和高压下合成。然而，这个过程会导致碳排放问题。在此，我们提出了一种电化学策略，在环境条件下直接将二氧化碳（

{CO}_{2}

）和 DMA 转化为 DMF。将钯（Pd）负载到具有 Cu 空位的铜（Cu）纳米片催化剂上，可实现 DMF 的高效合成;最大产量和法拉第效率可以分别达到

385 mmol \cdot h^{- 1} \cdot g_{cat} .^{- 1}

和

37.5 %

。原位表征和理论计算表明，Cu 空位促进了催化剂表面的

{CO}_{2}

吸附，随后与 DMA 自发耦合。Pd 纳米颗粒加速中间体 *

OCN {({CH}_{3})}_{2} OH

的电化学还原，导致高效的 DMF 电合成。这项工作指导了高值有机氮化合物的

{CO}_{2}

合成。
material for the preparation of polyurethane pastes, pharmaceutical products, pesticides, food additives, and electronics.

^{12}

Since Jouny et al. realized the electrochemical

C - N

coupling reaction using ammonia (

{NH}_{3}

) with CO in 2019, the construction of organic N compounds through this process has become a promising research direction.

^{13}

For example,

{CH}_{3} NO

has been prepared through the electrochemical reductive coupling of

{HCOO}^{-}

with nitrate (

{NO}_{3}^{-}

), electro-oxidative coupling of

{CH}_{3} OH

with

{NH}_{3}

, and electro-reductive coupling of CO with nitrite

({NO}_{2}^{-})

, thus expanding its synthesis pathways.

^{14 - 16}

Although there exist a few electrochemical

C - N

coupling reactions, the carbon sources for these reactions are

CO, {CH}_{3} OH

, and HCOOH , with most requiring a pre-treatment process to be obtained from fossil fuels.

^{17 - 19}

The direct use of

{CO}_{2}

as the carbon source for these reactions has the distinct advantage of simplifying the process to achieve clean conversion. However, the pathway complexity makes the direct synthesis of

{CH}_{3} NO

from

{CO}_{2}

quite challenging. Li and Kornienko et al. used a copper ( Cu ) catalyst to produce

{CH}_{3} NO

from

{CO}_{2}

and

{NH}_{3}

with a faradaic efficiency (FE) of only

0.3 % .^{20}

Therefore, there is an urgent need to understand the electroreduction process of

C - N

coupling from

{CO}_{2}

and explore electrocatalysts that achieve the synthesis of N -containing organic compounds directly from

{CO}_{2}

with a high FE .
用于制备聚氨酯浆料、药品、农药、食品添加剂和电子产品的材料。

^{12}

自 2019 年 Jouny 等实现了利用氨（

{NH}_{3}

）与 CO 的电化学

C - N

偶联反应以来，通过该工艺构建有机 N 化合物已成为一个有前景的研究方向。

^{13}

例如，

{CH}_{3} NO

通过与硝酸盐（）的

{HCOO}^{-}

电化学还原偶联

{NO}_{3}^{-}

、

{CH}_{3} OH

与的

{NH}_{3}

电氧化偶联、CO 与亚硝酸盐

({NO}_{2}^{-})

的电还原偶联等方法制备了，从而扩大了其合成途径。

^{14 - 16}

尽管存在一些电化学

C - N

偶联反应，但这些反应的碳源是

CO, {CH}_{3} OH

和 HCOOH ，其中大多数需要从化石燃料中获得预处理过程。直接用作

{CO}_{2}

这些反应的碳源

^{17 - 19}

具有简化过程以实现清洁转化的明显优势。然而，途径的复杂性使得

{CH}_{3} NO

直接合成来自

{CO}_{2}

相当具有挑战性。Li 和 Kornienko 等人使用铜（Cu）催化剂

{CH}_{3} NO

{CO}_{2}

{NH}_{3}

生产法拉第效率（FE）

0.3 % .^{20}

仅为因此，迫切需要了解偶

{CO}_{2}

联的

C - N

电还原过程，并探索直接从高 FE 中

{CO}_{2}

实现含 N 有机化合物合成的电催化剂。

Among all

{CH}_{3} NO

compounds,

N, N

-dimethylformamide (DMF) is known as the universal solvent due to its high chemical passivity and wide liquid phase range. The DMF market is projected to reach USD 2.7 billion by 2027, with a compound annual growth rate (CAGRof

3.2 %

during the forecast period.

^{21}

Currently, the DMF production relies on the synthesis of methyl formate (

C_{2} H_{4} O_{2}

) using CO and

{CH}_{3} OH

, followed by coupling with dimethylamine (DMA) under high temperatures (323-473 K ) and pressure (

0.5 - 11.0 MPa

). This process, however, is energy-intensive and generates large amounts of pollutants.

^{22, 23}

在所有

{CH}_{3} NO

化合物中，

N, N

-二甲基甲酰胺（DMF）因其高化学钝化性和宽液相范围而被称为通用溶剂。预计到 2027 年，DMF 市场将达到 27 亿美元，预测期内的复合年增长率（CAGRof

3.2 %

）。

^{21}

目前，DMF 的生产依赖于使用 CO

{CH}_{3} OH

合成甲酸甲酯（

C_{2} H_{4} O_{2}

），然后在高温（323-473 K）和高压下与二甲胺（DMA）偶联

0.5 - 11.0 MPa

（）。然而，这个过程是能源密集型的，会产生大量的污染物。

^{22, 23}

In this study, we implemented an electrocatalytic strategy for the synthesis of DMF via the coupling of

{CO}_{2}

and DMA on a Cu catalyst under ambient conditions (Figure 1). To further improve the performance of the coupling products, Cu vacancies

(Cu - V_{Cu})

were first generated to promote the adsorption of

{CO}_{2}

on the electrode surface, followed by its spontaneous coupling with DMA to form the *

OCNH {({CH}_{3})}_{2} O

intermediate. Subsequently, palladium (Pd) nanoparticles (NPs) were introduced on the electrode surface to accelerate the electrochemical hydrogenation process and generate *

OHCN {({CH}_{3})}_{2} OH

under the applied potential. In situ characterization and theoretical studies helped reveal the reaction pathway of

C - N

coupling. Using Pd-loaded Cu nanosheets with Cu vacancies (

Pd / Cu - V_{Cu}

) in a flow cell, we obtained a maximum DMF FE of

37.5 %

and yield of

385 mmol \cdot h^{- 1} \cdot g_{cat} .^{- 1}

. This process of sustainable electrochemical coupling of organic amines via

C O_{2}

is expected to be extended to the synthesis of other amides in future works.
在这项研究中，我们实施了一种电催化策略，通过在环境条件下在 Cu 催化剂上偶联

{CO}_{2}

和 DMA 来合成 DMF（图 1）。为了进一步提高偶联产物的性能，首先产生 Cu 空位

(Cu - V_{Cu})

以促进电极表面的

{CO}_{2}

吸附，然后与 DMA 自发偶联形成*

OCNH {({CH}_{3})}_{2} O

中间体。随后，在电极表面引入钯（Pd）纳米颗粒（NPs），以加速电化学加氢过程，并在施加电位下生成*

OHCN {({CH}_{3})}_{2} OH

。原位表征和理论研究有助于揭示偶联的

C - N

反应途径。在流通池中使用具有 Cu 空位（

Pd / Cu - V_{Cu}

）的 Pd 负载 Cu 纳米片，我们获得了最大 DMF FE 和

37.5 %

385 mmol \cdot h^{- 1} \cdot g_{cat} .^{- 1}

产率。这种有机胺的可持续电化学偶联过程

C O_{2}

有望在未来的工作中扩展到其他酰胺的合成。

RESULTS AND DISCUSSION 结果与讨论

Physical and chemical characterization of the prepared Cu electrocatalysts
所制备的 Cu 电催化剂的物理和化学表征

The preparation process of the pure Cu nanosheets, Cu nanosheets with

Cu - V_{Cu}

and the

Pd / Cu - V_{Cu}

catalyst is shown in Figure S 1 . The pure Cu nanosheet was synthesized by a chemical reduction method and placed in a quartz tube.

Cu - V_{Cu}

was constructed on the catalyst by argon (Ar) plasma etching.

^{24}

Finally, Pd was loaded onto the

Cu - V_{Cu}

surface through impregnation. The crystal structure and elemental composition of each nanosheet were confirmed prior to conducting the experiments. The X -ray diffraction (XRD) patterns of the

Cu, Cu - V_{Cu}

, and

Pd / Cu - V_{Cu}

sheets
纯 Cu 纳米片、Cu 纳米片和

Cu - V_{Cu}

Pd / Cu - V_{Cu}

催化剂的制备过程如图 S1 所示。通过化学还原法合成纯 Cu 纳米片，并置于石英管中。

Cu - V_{Cu}

通过氩（Ar）等离子体蚀刻在催化剂上构建。

^{24}

最后，通过浸渍将 Pd 加载到

Cu - V_{Cu}

表面。在进行实验之前，确认了每个纳米片的晶体结构和元素组成。

Cu, Cu - V_{Cu}

和片

Pd / Cu - V_{Cu}

材的 X 射线衍射（XRD）图案

$^{1}$ State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Advanced Catalytic Engineering Research Center of the Ministry of Education, Hunan University, Changsha 410082, P.R. China
$^{1}$ 湖南大学化学化工学院，高级催化工程研究中心，化学/生物传感与化学计量学国家重点实验室，湖南大学长沙 410082
$^{2}$ Jiangsu Co-Innovation Centre of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing
$^{2}$ 南京化工学院江苏省森林资源高效加工与利用协同创新中心
Forestry University, Nanjing, Jiangsu 210037, P.R. China
林业大学，中国江苏省南京市 210037
$^{3}$ Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials, Jiangsu Key Laboratory of New Power Batteries, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu 210037, P.R. China
$^{3}$ 南京师范大学化学与材料科学学院，江苏省新型动力电池重点实验室，江苏省生物医用功能材料协同创新中心，江苏省新型动力电池重点实验室，江苏南京 210037
$^{4}$ Department of Physics, Tamkang University, New Taipei City 25137, Taiwan
$^{4}$ 淡江大学物理系，台湾新北市 25137
$^{5}$ These authors contributed equally
$^{5}$ 这些作者的贡献相同
$^{6}$ Lead contact $^{6}$ 牵头联系人
*Correspondence: yuqin_zou@hnu.edu.cn https://doi.org/10.1016/j.chempr.2024.03.024
*对应关系：yuqin_zou@hnu.edu.cn https://doi.org/10.1016/j.chempr.2024.03.024

Chem 化学

Article 品

Electrochemical synthesis of formamide by CN coupling with amine and CO 2 CO 2 CO_(2)\mathrm{CO}_{2} with a high faradaic efficiency of 37.5%CN 与胺偶联电化学合成甲酰胺， CO 2 CO 2 CO_(2)\mathrm{CO}_{2} 法拉第效率高达 37.5%

Highlights 突出

Abstract 抽象

INTRODUCTION 介绍

THE BIGGER PICTURE 更大的图景

RESULTS AND DISCUSSION 结果与讨论

Physical and chemical characterization of the prepared Cu electrocatalysts所制备的 Cu 电催化剂的物理和化学表征

Electrochemical synthesis of formamide by CN coupling with amine and ${CO}_{2}$ with a high faradaic efficiency of 37.5%
CN 与胺偶联电化学合成甲酰胺， ${CO}_{2}$ 法拉第效率高达 37.5%

Physical and chemical characterization of the prepared Cu electrocatalysts
所制备的 Cu 电催化剂的物理和化学表征