Synthesis of Valeric Acid by Selective Electrocatalytic Hydrogenation of Biomass-Derived Levulinic Acid

The electrocatalytic hydrogenation (ECH) of biomass-derived levulinic acid (LA) is a promising strategy to synthetize fine chemicals under ambient conditions by replacing the thermocatalytic hydrogenation at high temperature and high pressure. Herein, various metallic electrodes were investigated in the ECH of LA in a H-type divided cell. The effects of potential, electrolyte concentration, reactant concentration, and temperature on catalytic performance and Faradaic efficiency were systematically explored. The high conversion of LA (93%) and excellent “apparent” selectivity to valeric acid (VA) (94%) with a Faradaic efficiency of 46% can be achieved over a metallic lead electrode in 0.5 M H2SO4 electrolyte containing 0.2 M LA at an applied voltage of −1.8 V (vs. Ag/AgCl) for 4 h. The combination of adsorbed LA and adsorbed hydrogen (Hads) on the surface of the metallic lead electrode is key to the formation of VA. Interestingly, the reaction performance did not change significantly after eight cycles, while the surface of the metallic lead cathode became rough, which may expose more active sites for the ECH of LA to VA. However, there was some degree of corrosion for the metallic lead cathode in this strong acid environment. Therefore, it is necessary to improve the leaching-resistance of the cathode for the ECH of LA in future research.

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Promoting CO2 methanation via ligand-stabilized metal oxide clusters as hydrogen-donating motifs

Nature Communications ◽

10.1038/s41467-020-20004-7 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Yuhang Li ◽

Aoni Xu ◽

Yanwei Lum ◽

Xue Wang ◽

Sung-Fu Hung ◽

...

Keyword(s):

Carbon Dioxide ◽

Metal Oxide ◽

Active Sites ◽

Density Functional ◽

Copper Catalyst ◽

Value Added ◽

Adsorbed Hydrogen ◽

Co2 Methanation ◽

Faradaic Efficiency ◽

Metal Oxide Clusters

AbstractElectroreduction uses renewable energy to upgrade carbon dioxide to value-added chemicals and fuels. Renewable methane synthesized using such a route stands to be readily deployed using existing infrastructure for the distribution and utilization of natural gas. Here we design a suite of ligand-stabilized metal oxide clusters and find that these modulate carbon dioxide reduction pathways on a copper catalyst, enabling thereby a record activity for methane electroproduction. Density functional theory calculations show adsorbed hydrogen donation from clusters to copper active sites for the *CO hydrogenation pathway towards *CHO. We promote this effect via control over cluster size and composition and demonstrate the effect on metal oxides including cobalt(II), molybdenum(VI), tungsten(VI), nickel(II) and palladium(II) oxides. We report a carbon dioxide-to-methane faradaic efficiency of 60% at a partial current density to methane of 135 milliampere per square centimetre. We showcase operation over 18 h that retains a faradaic efficiency exceeding 55%.

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Electrochemical Reduction of CO2: Overcoming Chemical Inertness at Ambient Conditions

Electrochem ◽

10.3390/electrochem1010006 ◽

2020 ◽

Vol 1 (1) ◽

pp. 56-59

Author(s):

Ana Cristina Perez ◽

Manuel Antonio Diaz-Perez ◽

Juan Carlos Serrano-Ruiz

Keyword(s):

Electrochemical Reduction ◽

Active Sites ◽

Storage System ◽

Reduction Process ◽

Electrochemical Reactor ◽

Great Promise ◽

Ambient Conditions ◽

Faradaic Efficiency ◽

Fine Control ◽

Reduction Of Co2

Electroreduction allows for the transformation of a chemically inert molecule such as CO2 into a wide variety of useful carbon products. Unlike other approaches operating at higher temperatures, electrochemical reduction holds great promise since it achieves reduction under ambient conditions, thereby providing more control over the reaction selectivity. By controlling basic parameters such as the potential and the composition of the electrode, CO2 can be transformed into a variety of products including carbon monoxide, syngas (CO/H2), methane, and methanol. This reduction process takes place without external hydrogen, since water can be used as a source of both electrons and protons. Furthermore, this technology, when combined with renewable wind- or solar-derived electricity, has the potential to serve as a storage system for excess electricity. Despite these advantages, a number of challenges need to be overcome before reaching commercialization. New (and cheaper) electrocatalyst formulations with high faradaic selectivities are required. Impressive progress has been made on carbon-doped materials, which, in certain cases, have outperformed expensive noble metal-based materials. Research is also needed on new electrochemical reactor configurations able to overcome kinetic/mass transport limitations, which are crucial to reduce overpotentials. Fine control over the nature of the active sites and the reaction conditions is important to avoid parasitic reactions such as the hydrogen evolution reaction (HER), and therefore increases the faradaic efficiency towards the desired products.

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Bimetallic metal–organic framework-derived MoFe-PC microspheres for electrocatalytic ammonia synthesis under ambient conditions

Journal of Materials Chemistry A ◽

10.1039/c9ta10524g ◽

2020 ◽

Vol 8 (4) ◽

pp. 2099-2104 ◽

Cited By ~ 5

Author(s):

Silong Chen ◽

Haeseong Jang ◽

Jia Wang ◽

Qing Qin ◽

Xien Liu ◽

...

Keyword(s):

Porous Structure ◽

Active Sites ◽

Ammonia Synthesis ◽

Metal Organic Framework ◽

High Yield ◽

Ambient Conditions ◽

Faradaic Efficiency ◽

Yield Rate ◽

Metal Organic ◽

Organic Framework

MoFe-PC exhibits a high yield rate and faradaic efficiency for NH3 electrosynthesis in acidic electrolytes due to the multicomponent active sites and inherent porous structure.

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Folic Acid Self-Assembly Enabling Manganese Single-Atom Electrocatalyst for Selective Nitrogen Reduction to Ammonia

Nano-Micro Letters ◽

10.1007/s40820-021-00651-1 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Xuewan Wang ◽

Dan Wu ◽

Suyun Liu ◽

Jiujun Zhang ◽

Xian-Zhu Fu ◽

...

Keyword(s):

Folic Acid ◽

Self Assembly ◽

Active Sites ◽

Density Functional ◽

Carbon Matrix ◽

Single Atom ◽

Synthesis Process ◽

Ambient Conditions ◽

Hydrogen Electrode ◽

Faradaic Efficiency

AbstractEfficient and robust single-atom catalysts (SACs) based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia (NRR) under ambient conditions. Herein, for the first time, a Mn–N–C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy. The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation. Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix, the catalyst exhibits excellent activity for NRR with high activity and selectivity, achieving a high Faradaic efficiency of 32.02% for ammonia synthesis at − 0.45 V versus reversible hydrogen electrode. Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N2 adsorption, activation and selective reduction to NH3 by the distal mechanism. This work provides a simple synthesis process for Mn–N–C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites. Graphic Abstract

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Altering the rate-determining step over cobalt single clusters leading to highly efficient ammonia synthesis

National Science Review ◽

10.1093/nsr/nwaa136 ◽

2020 ◽

Cited By ~ 1

Author(s):

Sisi Liu ◽

Mengfan Wang ◽

Haoqing Ji ◽

Xiaowei Shen ◽

Chenglin Yan ◽

...

Keyword(s):

Active Sites ◽

Density Functional ◽

Ammonia Synthesis ◽

Density Functional Theory Calculations ◽

High Energy ◽

Ambient Conditions ◽

Property A ◽

Strong Electron ◽

Faradaic Efficiency ◽

Rate Determining Step

Abstract Activation of high-energy triple-bonds of N2 is the most significant bottleneck of ammonia synthesis under ambient conditions. Here, by importing cobalt single clusters as strong electron-donating promoter into the catalyst, the rate-determining step of ammonia synthesis is altered to the subsequent proton addition so that the barrier of N2 dissociation can be successfully overcome. As revealed by density functional theory calculations, the N2 dissociation becomes exothermic over the cobalt single cluster upon the strong electron backdonation from metal to the N2 antibonding orbitals. The energy barrier of the positively shifted rate-determining step is also greatly reduced. At the same time, advanced sampling molecular dynamics simulations indicate a barrier-less process of the N2 approaching the active sites that greatly facilitates the mass transfer. With suitable thermodynamic and dynamic property, a high ammonia yield rate of 76.2 μg h–1 mg$^{-1 }_{\rm cat.}$ and superior Faradaic efficiency of 52.9% were simultaneously achieved.

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Electrocatalytic Conversion of Levulinic Acid in Acid Medium

Journal of Siberian Federal University Chemistry ◽

10.17516/1998-2836-0263 ◽

2021 ◽

Vol 14 (4) ◽

pp. 561-569

Author(s):

Tatyana A. Kenova ◽

◽

Nikolay A. Zos’ko ◽

Valentin V. Sychev ◽

Oxana P. Taran

Keyword(s):

Acid Medium ◽

Glassy Carbon ◽

Levulinic Acid ◽

Valeric Acid ◽

Carbon Electrodes ◽

H2so4 Solution ◽

Electrochemical Hydrogenation ◽

Faradaic Efficiency ◽

Glassy Carbon Electrodes ◽

First Time

The electrochemical hydrogenation of levulinic acid in H2SO4 solution at aluminium, lead, graphite and glassy carbon electrodes is studied. The process is identified to proceed selectively to valeric acid. The conversion, selectivity and faradaic efficiency are significantly influenced by the material electrode nature. The levulinic acid hydrogenation at glassy carbon is shown for the first time to proceed to valeric acid, and the process selectivity is affected by the concentration of surface functionalities

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Efficient dinitrogen fixation on porous covalent organic framework/carbon nanotubes hybrid at low overpotential

Functional Materials Letters ◽

10.1142/s1793604721510279 ◽

2021 ◽

pp. 2151027

Author(s):

Qiming Yu ◽

Hongming Wang

Keyword(s):

Carbon Nanotubes ◽

Active Sites ◽

Rational Design ◽

Ammonia Synthesis ◽

Theoretical Calculations ◽

Ambient Conditions ◽

Hydrogen Electrode ◽

Faradaic Efficiency ◽

Covalent Organic Framework ◽

Organic Framework

Electrocatalytic nitrogen reduction under ambient conditions is a promising approach for ammonia synthesis, but it is challenging to develop highly efficient electrocatalysts. In this work, a hybrid of covalent organic framework (COF) and carbon nanotubes (CNTs) are developed for efficient nitrogen electroreduction with a high faradaic efficiency (FE) of 12.7% at 0.0 V versus reversible hydrogen electrode (RHE) and a remarkable production rate of ammonia up to 8.56 [Formula: see text]g h[Formula: see text] mg[Formula: see text] at –0.2 V versus RHE. Experiments and theoretical calculations reveal that Ni centers are active sites for NH3 synthesis, while the [Formula: see text]–[Formula: see text] stacking between COF-366-Ni and conductive CNTs scaffold results in the rapid interfacial charge transfer. This investigation provides new insights on the rational design of organic–inorganic porous hybrids for efficient nitrogen conversion and ammonia synthesis at ambient conditions.

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Enhancing electrocatalytic N2 conversion to NH3 by MnO2 ultralong nanowires with oxygen vacancies

Journal of Photocatalysis ◽

10.2174/2665976x02666210407142545 ◽

2021 ◽

Vol 02 ◽

Author(s):

Guangbin Wang ◽

Renna Zhao ◽

Fahao Ma ◽

Zeyan Wang ◽

Peng Wang ◽

...

Keyword(s):

Active Sites ◽

Manganese Oxides ◽

Oxygen Vacancies ◽

High Energy ◽

Reduction Reaction ◽

Ambient Conditions ◽

Hydrogen Electrode ◽

Faradaic Efficiency ◽

Vacancy Defects ◽

One Step

Background: At present, industrial synthesis of NH3 mainly relies on the Haber-Bosch process, which is characterized by harsh reaction conditions and high energy consumption. Electrochemical nitrogen reduction is considered to be a mild and sustainable alternative method for producing NH3, but efficient electrocatalyst under ambient conditions is the prerequisite for NH3 production. Objective: To demonstrate that CP@MnO2 ultralong nanowires is a highly-efficient electrocatalyst for N2 reduction reaction (NRR) under ambient conditions. Methods: The α-phase MnO2 synthesized by one-step hydrothermal method has an ultralong nanowires structure and oxygen vacancy defects. The catalysts was characterized by XRD, TEM, XPS, etc. The produced NH3 was estimated by indophenol blue method by UV-vis absorption spectra. Results: Such catalyst attains high Faradaic efficiency (FE) of 8.8% and a large NH3 yield of 1.13×10−10 mol cm−2 s−−1 at −0.7 V versus reversible hydrogen electrode in 0.1 M Na2SO4. In addition, the catalyst also shows high electrochemical stability and selectivity for NH3 formation. Conclusion: MnO2 ultralong nanowires can expose higher density of active sites and the spontaneously formed oxygen vacancies can manipulate the electronic structure of manganese oxides and provide coordination unsaturation sites (CUS) to enhance the adsorption of N2, which is the main reason for the high activity of the catalyst.

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Designing Oxide Aerogels With Enhanced Sorptive and Degradative Activity for Acute Chemical Threats

Frontiers in Materials ◽

10.3389/fmats.2021.674798 ◽

2021 ◽

Vol 8 ◽

Author(s):

Travis G. Novak ◽

Paul A. DeSario ◽

Jeffrey W. Long ◽

Debra R. Rolison

Keyword(s):

Surface Area ◽

Metallic Nanoparticles ◽

Active Sites ◽

High Surface ◽

High Surface Area ◽

Future Research ◽

Ambient Conditions ◽

Industrial Chemicals ◽

Sorptive Capacity ◽

Toxic Industrial Chemicals

Oxide aerogels are pore–solid networks notable for their low density, large pore volume, and high surface area. This three-dimensional arrangement of pore and solid provides critical properties: the high surface area required to maximize the number of active sites and a through-connected porosity that plumbs reactants to the active interior. In decontamination applications where reactivity beyond adsorption is desired to degrade deleterious molecules, oxide aerogels offer multiple avenues to add oxidative power to this unique arrangement of pore and solid. For protection against chemical warfare agents or toxic industrial chemicals, metal-oxide aerogels with their oxide/hydroxide surfaces afford stability under ambient conditions against competing sorbents such as water and oxygen. In this review, strategies to maximize sorptive capacity and degradation rate by modifying surface functionality, compositing with dissimilar oxides, or adding metallic nanoparticles and the subsequent impact on decontamination performance will be summarized and expected directions for future research will be discussed based on the observed trends.

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Electrokinetic and in situ spectroscopic investigations of CO electrochemical reduction on copper

Nature Communications ◽

10.1038/s41467-021-23582-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jing Li ◽

Xiaoxia Chang ◽

Haochen Zhang ◽

Arnav S. Malkani ◽

Mu-jeng Cheng ◽

...

Keyword(s):

Mass Transport ◽

Active Sites ◽

Gas Diffusion ◽

Reduction Reaction ◽

Adsorbed Hydrogen ◽

Diffusion Type ◽

Proton Coupled Electron Transfer ◽

Alkaline Electrolytes ◽

Reaction Orders

AbstractRigorous electrokinetic results are key to understanding the reaction mechanisms in the electrochemical CO reduction reaction (CORR), however, most reported results are compromised by the CO mass transport limitation. In this work, we determined mass transport-free CORR kinetics by employing a gas-diffusion type electrode and identified dependence of catalyst surface speciation on the electrolyte pH using in-situ surface enhanced vibrational spectroscopies. Based on the measured Tafel slopes and reaction orders, we demonstrate that the formation rates of C2+ products are most likely limited by the dimerization of CO adsorbate. CH4 production is limited by the CO hydrogenation step via a proton coupled electron transfer and a chemical hydrogenation step of CO by adsorbed hydrogen atom in weakly (7 < pH < 11) and strongly (pH > 11) alkaline electrolytes, respectively. Further, CH4 and C2+ products are likely formed on distinct types of active sites.

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