Robust coal matrix intensifies electron/substrate interaction of nickel-nitrogen (Ni-N) active sites for efficient CO2 electroreduction at industrial current density

AbstractAlthough Fe–N/C catalysts have received increasing attention in recent years for oxygen reduction reaction (ORR), it is still challenging to precisely control the active sites during the preparation. Herein, we report FexN@RGO catalysts with the size of 2–6 nm derived from the pyrolysis of graphene oxide and 1,1′-diacetylferrocene as C and Fe precursors under the NH3/Ar atmosphere as N source. The 1,1′-diacetylferrocene transforms to Fe3O4 at 600°C and transforms to Fe3N and Fe2N at 700°C and 800°C, respectively. The as-prepared FexN@RGO catalysts exhibited superior electrocatalytic activities in acidic and alkaline media compared with the commercial 10% Pt/C, in terms of electrochemical surface area, onset potential, half-wave potential, number of electrons transferred, kinetic current density, and exchange current density. In addition, the stability of FGN-8 also outperformed commercial 10% Pt/C after 10000 cycles, which demonstrates the as-prepared FexN@RGO as durable and active ORR catalysts in acidic media.

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Facile Synthesis of Carbon Cloth Supported Cobalt Carbonate Hydroxide Hydrate Nanoarrays for Highly Efficient Oxygen Evolution Reaction

Frontiers in Chemistry ◽

10.3389/fchem.2021.754357 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yubing Yan

Keyword(s):

Electron Microscopy ◽

Oxygen Evolution ◽

Current Density ◽

Oxygen Evolution Reaction ◽

Active Sites ◽

Carbon Cloth ◽

High Porosity ◽

Cobalt Carbonate ◽

Carbonate Hydroxide ◽

Hydroxide Hydrate

Developing efficient and low-cost replacements for noble metals as electrocatalysts for the oxygen evolution reaction (OER) remain a great challenge. Herein, we report a needle-like cobalt carbonate hydroxide hydrate (Co(CO3)0.5OH·0.11H2O) nanoarrays, which in situ grown on the surface of carbon cloth through a facile one-step hydrothermal method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations demonstrate that the Co(CO3)0.5OH nanoarrays with high porosity is composed of numerous one-dimensional (1D) nanoneedles. Owing to unique needle-like array structure and abundant exposed active sites, the Co(CO3)0.5OH@CC only requires 317 mV of overpotential to reach a current density of 10 mA cm−2, which is much lower than those of Co(OH)2@CC (378 mV), CoCO3@CC (465 mV) and RuO2@CC (380 mV). For the stability, there is no significant attenuation of current density after continuous operation 27 h. This work paves a facile way to the design and construction of electrocatalysts for the OER.

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CO2 electrolysis to multicarbon products in strong acid

Science ◽

10.1126/science.abg6582 ◽

2021 ◽

Vol 372 (6546) ◽

pp. 1074-1078

Author(s):

Jianan Erick Huang ◽

Fengwang Li ◽

Adnan Ozden ◽

Armin Sedighian Rasouli ◽

F. Pelayo García de Arquer ◽

...

Keyword(s):

Carbon Dioxide ◽

Hydrogen Evolution ◽

Current Density ◽

Carbon Emissions ◽

Active Sites ◽

Cell Voltage ◽

Strong Acid ◽

Electrochemically Active ◽

Co2 Electrolysis ◽

A Current

Carbon dioxide electroreduction (CO2R) is being actively studied as a promising route to convert carbon emissions to valuable chemicals and fuels. However, the fraction of input CO2 that is productively reduced has typically been very low, <2% for multicarbon products; the balance reacts with hydroxide to form carbonate in both alkaline and neutral reactors. Acidic electrolytes would overcome this limitation, but hydrogen evolution has hitherto dominated under those conditions. We report that concentrating potassium cations in the vicinity of electrochemically active sites accelerates CO2 activation to enable efficient CO2R in acid. We achieve CO2R on copper at pH <1 with a single-pass CO2 utilization of 77%, including a conversion efficiency of 50% toward multicarbon products (ethylene, ethanol, and 1-propanol) at a current density of 1.2 amperes per square centimeter and a full-cell voltage of 4.2 volts.

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Revealing active sites in N-doped carbon for CO2 electroreduction by well-defined molecular model catalysts

Science Bulletin ◽

10.1016/j.scib.2020.03.011 ◽

2020 ◽

Vol 65 (10) ◽

pp. 781-782 ◽

Cited By ~ 1

Author(s):

Run Shi ◽

Tierui Zhang

Keyword(s):

Active Sites ◽

Molecular Model ◽

Model Catalysts ◽

Co2 Electroreduction

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Discovery of main group single Sb–N4 active sites for CO2 electroreduction to formate with high efficiency

Energy & Environmental Science ◽

10.1039/d0ee01486a ◽

2020 ◽

Vol 13 (9) ◽

pp. 2856-2863 ◽

Cited By ~ 10

Author(s):

Zhuoli Jiang ◽

Tao Wang ◽

Jiajing Pei ◽

Huishan Shang ◽

Danni Zhou ◽

...

Keyword(s):

Active Sites ◽

High Efficiency ◽

Main Group ◽

Single Atom ◽

Carbon Nanosheets ◽

Co2 Electroreduction

We discover that an Sb single atom material consisting of Sb–N4 moieties anchored on N-doped carbon nanosheets can serve as a CO2RR catalyst to produce formate with high efficiency.

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FeNC catalysts for CO2 electroreduction to CO: effect of nanostructured carbon supports

Sustainable Energy & Fuels ◽

10.1039/c9se00214f ◽

2019 ◽

Vol 3 (7) ◽

pp. 1833-1840 ◽

Cited By ~ 3

Author(s):

Dilan Karapinar ◽

Ngoc-Huan Tran ◽

Domitille Giaume ◽

Nastaran Ranjbar ◽

Frédéric Jaouen ◽

...

Keyword(s):

Carbon Nanofibers ◽

Current Density ◽

Carbon Materials ◽

Nanostructured Carbon ◽

Carbon Supports ◽

Nitrogen Doped ◽

Co2 Electroreduction ◽

Nitrogen Doped Carbon

Iron- and nitrogen-doped carbon materials (FeNC) are excellent catalysts for CO2 electroreduction to CO. Current density and selectivity can be significantly improved by mixing FeNC with carbon materials such as carbon nanofibers.

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Steps in the reactions of proteolytic enzymes with their substrates

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1970.0012 ◽

1970 ◽

Vol 257 (813) ◽

pp. 105-110 ◽

Cited By ~ 8

Keyword(s):

Active Sites ◽

Dissociation Constants ◽

Proteolytic Enzymes ◽

Substrate Binding ◽

Hydrolytic Enzymes ◽

Dimensional Structure ◽

Chemical Information ◽

Substrate Interaction ◽

Enzyme Substrate ◽

Wide Range

Kinetic experiments should be designed to answer specific questions about a reaction mechanism. The present paper is intended to show how a number of specific questions have been answered. Chymotrypsin and trypsin are mainly used to illustrate the different approaches, but many of the arguments used are equally applicable to the reactions of other hydrolytic enzymes with serine-OH or cysteine-SH at the active site. T he recognition of serine-OH and cysteine-SH as essential groups at the active sites of different hydrolytic enzymes did not rest on kinetic evidence. This was deduced from the correlation of enzyme activity with the extent of modification of specially reactive groups. The investigation of proton dissociation equilibria and the assignment of dissociation constants to groups with specified functions in substrate binding, catalysis or protein conformation was the first objective of serious kinetic studies of enzyme reactions. Steady state rate measurements over a wide range of pH showed that groups with p K 6.25 and 6.85 respectively are involved in the catalytic activity of trypsin and chymotrypsin with certain specific substrates (Hammond & Gutfreund 1955). In the case of chymotrypsin it was also shown by Hammond & Gutfreund (1955) that a group with a more alkaline pK is involved in substrate binding. This latter group was subsequently identified and its function was elucidated through the elegant experiments of Oppenheimer, Labouresse & Hess (1966). The identification of histidine as the group with p K A near neutrality, involved in the catalytic mechanism of trypsin and chymotrypsin, was subsequently confirmed by direct chemical methods by Schoelmann & Shaw (1963). Only kinetic analysis can demonstrate the involvement of proton donors or acceptors with specific properties in enzyme-substrate interaction or in catalysis. The clear identification of chemical groups capable of performing such functions is coming from the crystallographic analysis of the three-dimensional structure at the site of enzyme-substrate interaction, as illustrated in other papers presented in this discussion. Very interesting chemical information is obtained when the effect of structure on reactivity is synthesized from the composite of crystallographic and kinetic data.

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Flexible freestanding MoS2 based paper-like material for energy conversion and storage

10.3762/bxiv.2019.24.v1 ◽

2019 ◽

Author(s):

Florian Zoller ◽

Jan Luxa ◽

Thomas Bein ◽

Dina Fattakhova-Rohlfing ◽

Daniel Bousa ◽

...

Keyword(s):

Composite Material ◽

Energy Storage ◽

Mechanical Strength ◽

Current Density ◽

Active Sites ◽

Specific Capacity ◽

Lithium Ion ◽

High Energy ◽

Onset Potential ◽

High Flexibility

Construction of flexible electrochemical devices for energy storage and generation is of utmost importance in the modern society. In this article, we report the synthesis of flexible MoS2 based composite paper by high-energy shear force milling and simple vacuum filtration. This composite material combines high flexibility, mechanical strength and good chemical stability. Chronopotentiometric charge-discharge measurements were used to determine the capacitance of our paper material. Highest capacitance of 33 mF cm-2 was achieved at current density of 1 mA cm-2 showing potential application in supercapacitors. We further used the material as a cathode for hydrogen evolution reaction (HER) with an onset potential of ca. -0.2 V vs RHE. The onset potential was even lower (ca. -0.1 V vs RHE) after treatment with n-butyllithium suggesting the introduction of new active sites. Finally, a potential use in Lithium ion batteries (LIB) was examined. Our material can be used directly without any binder, additive carbon or copper current collector and delivers specific capacity of 740 mA h g-1 at a current density of 0.1 A g-1. After 40 cycles at this current density the material still reached a capacity retention of 91%. Our findings show that this composite material could find application in electrochemical energy storage and generation devices where high flexibility and mechanical strength are desired.

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Electrodeposited Copper Nanocatalysts for CO2 Electroreduction: Effect of Electrodeposition Conditions on Catalysts’ Morphology and Selectivity

Energies ◽

10.3390/en14165012 ◽

2021 ◽

Vol 14 (16) ◽

pp. 5012

Author(s):

Gianluca Zanellato ◽

Pier Giorgio Schiavi ◽

Robertino Zanoni ◽

Antonio Rubino ◽

Pietro Altimari ◽

...

Keyword(s):

Carbon Dioxide ◽

Current Density ◽

Electrical Energy ◽

Gas Diffusion ◽

Dodecyltrimethylammonium Bromide ◽

Xps Analysis ◽

Gaseous Products ◽

Co2 Electroreduction ◽

Catalyst Morphology ◽

Deposition Current Density

Catalytic electroreduction of carbon dioxide represents a promising technology both to reduce CO2 emissions and to store electrical energy from discontinuous sources. In this work, electrochemical deposition of copper on to a gas-diffusion support was tested as a scalable and versatile nanosynthesis technique for the production of catalytic electrodes for CO2 electroreduction. The effect of deposition current density and additives (DAT, DTAB, PEG) on the catalysts’ structure was evaluated. The selectivity of the synthesized catalysts towards the production of CO was evaluated by analyzing the gaseous products obtained using the catalysts as cathodes in electroreduction tests. Catalyst morphology was deeply influenced by the deposition additives. Copper nanospheres, hemispherical microaggregates of nanowires, and shapeless structures were electrodeposited in the presence of dodecyltrimethylammonium bromide (DTAB), 3,5-diamino-1,2,4-triazole (DAT) and polyethylene glycol (PEG), respectively. The effect of the deposition current density on catalyst morphology was also observed and it was found to be additive-specific. DTAB nanostructured electrodes showed the highest selectivity towards CO production, probably attributable to a higher specific surface area. EDX and XPS analysis disclosed the presence of residual DAT and DTAB uniformly distributed onto the catalysts structure. No significant effects of electrodeposition current density and Cu(I)/Cu(II) ratio on the selectivity towards CO were found. In particular, DTAB and DAT electrodes yielded comparable selectivity, although they were characterized by the highest and lowest Cu(I)/Cu(II) ratio, respectively.

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