Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

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Boosting proton reduction via isolated Cu atoms in Bi lattice for efficient electroreduction of CO2 to formate

10.21203/rs.3.rs-422256/v1 ◽

2021 ◽

Author(s):

Pei-Pei Luo ◽

Hong-Juan Wang ◽

Lina Li ◽

Bing Nan ◽

Yu Li ◽

...

Keyword(s):

Current Density ◽

Energy Barrier ◽

Identical Condition ◽

High Energy ◽

Single Atom ◽

Proton Reduction ◽

Faradaic Efficiency ◽

High Energy Barrier ◽

New Strategy ◽

Alloy Catalyst

Abstract Current Bi-based catalysts suffer from low current density for electroreduction of CO2 to formate due to the high energy barrier of H+ reduction to *H on Bi sites. Here we report a unique BiCu single-atom alloy catalyst (SAAC) that can deliver a ultrahigh formate partial current density (jformate) of 434 mA cm–2, the highest among the reported Bi-based electrocatalysts to date, with a formate Faradaic efficiency (FEformate) of 96.5% at –0.55 V (vs. RHE) in a flow cell, while BiCu alloy catalyst containing Cu nanoclusters can only deliver a jformate of 48.5 mA cm–2 with a FEformate of 37.3% under an identical condition. Mechanism investigations reveal that the isolated single-atom Cu in BiCu SAAC can dramatically reduce the energy barrier of H+ reduction to *H on Cu site for boosting the reduction of CO2 to formate. Our work provides a new strategy for engineering unfavourable energy barrier of electrocatalysts to promote CO2 reduction.

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Regulating the coordination structure of single-atom Fe-NxCy catalytic sites for benzene oxidation

Nature Communications ◽

10.1038/s41467-019-12362-8 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 39

Author(s):

Yuan Pan ◽

Yinjuan Chen ◽

Konglin Wu ◽

Zheng Chen ◽

Shoujie Liu ◽

...

Keyword(s):

Active Sites ◽

Reaction Pathway ◽

Theoretical Calculations ◽

Single Atom ◽

Coordination Pattern ◽

Benzene Oxidation ◽

Coordination Environment ◽

Catalytic Sites ◽

Coordination Effect ◽

Oxidative Species

Abstract Atomically dispersed metal-N-C structures are efficient active sites for catalyzing benzene oxidation reaction (BOR). However, the roles of N and C atoms are still unclear. We report a polymerization-regulated pyrolysis strategy for synthesizing single-atom Fe-based catalysts, and present a systematic study on the coordination effect of Fe-NxCy catalytic sites in BOR. The special coordination environment of single-atom Fe sites brings a surprising discovery: Fe atoms anchored by four-coordinating N atoms exhibit the highest BOR performance with benzene conversion of 78.4% and phenol selectivity of 100%. Upon replacing coordinated N atoms by one or two C atoms, the BOR activities decrease gradually. Theoretical calculations demonstrate the coordination pattern influences not only the structure and electronic features, but also the catalytic reaction pathway and the formation of key oxidative species. The increase of Fe-N coordination number facilitates the generation and activation of the crucial intermediate O=Fe=O species, thereby enhancing the BOR activity.

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Theoretical research on a coke-resistant catalyst for the partial oxidation of methane: Pt/Cu single-atom alloys

New Journal of Chemistry ◽

10.1039/c9nj04723a ◽

2020 ◽

Vol 44 (10) ◽

pp. 3922-3929 ◽

Cited By ~ 1

Author(s):

Yuanyuan Meng ◽

Chuanmin Ding ◽

Yuyuan Xue ◽

Xiaofeng Gao ◽

Kan Zhang ◽

...

Keyword(s):

Energy Barrier ◽

Bond Activation ◽

Carbon Deposition ◽

High Energy ◽

Theoretical Research ◽

Single Atom ◽

Oxidation Of Methane ◽

High Energy Barrier ◽

Weak Adsorption ◽

Single Atom Alloys

Cu can prevent carbon deposition on a surface due to weak adsorption, but it exhibits a high energy barrier to C–H bond activation, which means that it is not practical.

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Enhancing the energy barrier and hysteresis temperature in two benchtop-stable Ho(III) single-ion magnets

Chemical Communications ◽

10.1039/d1cc00582k ◽

2021 ◽

Author(s):

Kexin Jia ◽

Xixi Meng ◽

Mengmeng Wang ◽

Xiaoshuang Gou ◽

Yu-Xia Wang ◽

...

Keyword(s):

Energy Barrier ◽

High Energy ◽

Halogen Anion ◽

High Energy Barrier

The energy barrier and hysteresis temperature in two benchtop-stable D5h-symmetry HoIII single-ion magnets were significantly enhanced via the variation of halogen anion. The coexistence of high energy barrier of 418...

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Efficient electrocatalytic nitrogen reduction to ammonia with aqueous silver nanodots

Communications Chemistry ◽

10.1038/s42004-021-00449-7 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Wenyi Li ◽

Ke Li ◽

Yixing Ye ◽

Shengbo Zhang ◽

Yanyan Liu ◽

...

Keyword(s):

Active Sites ◽

Theoretical Calculations ◽

Current Collector ◽

Electrochemical Reactor ◽

Reduction Reaction ◽

Solution Ph ◽

Faradaic Efficiency ◽

Yield Rate ◽

Silver Nanodots ◽

Ti Mesh

AbstractThe electrocatalytic nitrogen (N2) reduction reaction (NRR) relies on the development of highly efficient electrocatalysts and electrocatalysis systems. Herein, we report a non-loading electrocatalysis system, where the electrocatalysts are dispersed in aqueous solution rather than loading them on electrode substrates. The system consists of aqueous Ag nanodots (AgNDs) as the catalyst and metallic titanium (Ti) mesh as the current collector for electrocatalytic NRR. The as-synthesized AgNDs, homogeneously dispersed in 0.1 M Na2SO4 solution (pH = 10.5), can achieve an NH3 yield rate of 600.4 ± 23.0 μg h−1 mgAg−1 with a faradaic efficiency (FE) of 10.1 ± 0.7% at −0.25 V (vs. RHE). The FE can be further improved to be 20.1 ± 0.9% at the same potential by using Ti mesh modified with oxygen vacancy-rich TiO2 nanosheets as the current collector. Utilizing the aqueous AgNDs catalyst, a Ti plate based two-electrode configured flow-type electrochemical reactor was developed to achieve an NH3 yield rate of 804.5 ± 30.6 μg h−1 mgAg−1 with a FE of 8.2 ± 0.5% at a voltage of −1.8 V. The designed non-loading electrocatalysis system takes full advantage of the AgNDs’ active sites for N2 adsorption and activation, following an alternative hydrogenation mechanism revealed by theoretical calculations.

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Slow magnetic relaxation in dinuclear dysprosium and holmium phenoxide bridged complexes: a Dy2 single molecule magnet with a high energy barrier

Inorganic Chemistry Frontiers ◽

10.1039/d1qi00152c ◽

2021 ◽

Author(s):

Matilde Fondo ◽

Julio Corredoira-Vázquez ◽

Ana M. Garcia-Deibe ◽

Jesus Sanmartin Matalobos ◽

Silvia Gómez-Coca ◽

...

Keyword(s):

Crystal Structures ◽

Single Molecule ◽

Energy Barrier ◽

Magnetic Relaxation ◽

High Energy ◽

Single Molecule Magnet ◽

High Energy Barrier ◽

Slow Magnetic Relaxation

Dinuclear [M(H3L1,2,4)]2 (M = Dy, Dy2; M = Ho, Ho2) complexes were isolated from an heptadentate aminophenol ligand. The crystal structures of Dy2·2THF, and the pyridine adducts Dy2·2Py and Ho2·2Py,...

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First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633615500200 ◽

2015 ◽

Vol 14 (03) ◽

pp. 1550020 ◽

Cited By ~ 3

Author(s):

Yuan Yuan ◽

Wei Hu ◽

Xuhui Chi ◽

Cuihua Li ◽

Dayong Gui ◽

...

Keyword(s):

Diethyl Ether ◽

Energy Barrier ◽

Density Functional ◽

Oxidation Process ◽

Oxidation Mechanism ◽

High Energy ◽

First Principle ◽

Functional Theory ◽

The Third ◽

High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

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