scholarly journals Substituent-induced electronic localization of nickel phthalocyanine with enhanced electrocatalytic CO2 reduction

2021 ◽  
Author(s):  
Kejun Chen ◽  
Maoqi Cao ◽  
Yiyang Lin ◽  
Junwei Fu ◽  
Hanxiao Liao ◽  
...  
Keyword(s):  
Co2 Reduction ◽  
Catalytic Performance ◽  
Flow Cell ◽  
Reduction Reaction ◽  
Nickel Phthalocyanine ◽  
Localization Strategy ◽  
Current Densities ◽  
Electronic Localization ◽  
Novel Strategy ◽  
Electron Deficiency

Abstract Designing efficient catalysts with high activity and selectivity is desirable and challenging for CO2 reduction reaction (CO2RR). Nickel phthalocyanine (NiPc) is a promising molecule catalyst for CO2RR. However, the pristine NiPc suffers from poor CO2 adsorption and activation due to its electron deficiency of Ni–N4 site, which leads to inferior activity and stability during CO2RR. Here, we develop a substituent-induced electronic localization strategy to improve CO2 adsorption and activation, and thus catalytic performance. Theoretic calculations and experimental results indicate that the electronic localization on the Ni site induced by electron-donating substituents (hydroxyl or amino) of NiPc greatly enhances the CO2 adsorption and activation, which is positively associated with the electron-donating abilities of substituents. Employing the optimal catalyst of amino-substituted NiPc to catalyze CO2 into CO in flow cell can achieve an ultrahigh activity and selectivity of 99.8% at the current densities up to 400 mA cm-2. This work offers a novel strategy to regulate the electronic structure of the active site by introducing substituents for highly efficient CO2RR.

scholarly journals Molecular electrocatalysts transform CO into C2+ products effectively in a flow cell

2020 ◽  
Author(s):  
Shaoxuan Ren ◽  
Arthur Fink ◽  
Eric Lees ◽  
Zishuai Zhang ◽  
Wen Yu Wu ◽  
...  
Keyword(s):  
Copper Phthalocyanine ◽  
Co2 Reduction ◽  
Product Formation ◽  
Flow Cell ◽  
Reduction Reaction ◽  
Flow Cells ◽  
New Class ◽  
Current Densities ◽  
Co2 Reduction Reaction ◽  
Co2 Electrolysis

Abstract The highest performance flow cells capable of electrolytically converting CO2 into higher value chemicals and fuels pass a concentrated hydroxide electrolyte across the cathode. A major problem for CO2 electrolysis is that this strongly alkaline medium converts the majority of CO2 into unreactive HCO3– and CO32– rather than CO2 reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO2) does not suffer from this same problem because CO does not react with hydroxide. Moreover, CO can be more readily converted into products containing two or more carbon atoms (i.e., C2+ products). While several solid-state electrocatalysts have proven competent at converting CO into C2+ products, we demonstrate here that molecular electrocatalysts are also effective at mediating this transformation in a flow cell. Using a molecular copper phthalocyanine (CuPc) electrocatalyst, CO was electrolyzed into C2+ products at high rates of product formation (i.e., current densities J ≥200 mA/cm2), and at high Faradaic efficiencies for C2+ production (FEC2+; 72% at 200 mA/cm2). These findings present a new class of electrocatalysts for making carbon-neutral chemicals and fuels.

Molecular electrocatalysts can mediate fast, selective CO2 reduction in a flow cell

Science ◽  
2019 ◽  
Vol 365 (6451) ◽  
pp. 367-369 ◽  
Author(s):  
Shaoxuan Ren ◽  
Dorian Joulié ◽  
Danielle Salvatore ◽  
Kristian Torbensen ◽  
Min Wang ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Co2 Reduction ◽  
Reduction Reaction ◽  
Operating Conditions ◽  
High Current ◽  
Membrane Flow ◽  
Molecular Catalyst ◽  
Current Densities ◽  
Molecular Catalysts ◽  
Distinct Approach

Practical electrochemical carbon dioxide (CO2) conversion requires a catalyst capable of mediating the efficient formation of a single product with high selectivity at high current densities. Solid-state electrocatalysts achieve the CO2 reduction reaction (CO2RR) at current densities ≥ 150 milliamperes per square centimeter (mA/cm2), but maintaining high selectivities at high current densities and efficiencies remains a challenge. Molecular CO2RR catalysts can be designed to achieve high selectivities and low overpotentials but only at current densities irrelevant to commercial operation. We show here that cobalt phthalocyanine, a widely available molecular catalyst, can mediate CO2 to CO formation in a zero-gap membrane flow reactor with selectivities > 95% at 150 mA/cm2. The revelation that molecular catalysts can work efficiently under these operating conditions illuminates a distinct approach for optimizing CO2RR catalysts and electrolyzers.

scholarly journals CO2 reduction on gas-diffusion electrodes and why catalytic performance must be assessed at commercially-relevant conditions

2019 ◽  
Vol 12 (5) ◽  
pp. 1442-1453 ◽  
Author(s):  
Thomas Burdyny ◽  
Wilson A. Smith
Keyword(s):  
Local Reaction ◽  
Co2 Reduction ◽  
Catalytic Performance ◽  
Gas Diffusion ◽  
High Current ◽  
Gas Diffusion Electrodes ◽  
Current Densities ◽  
Current Practices

The substantial implications of high current densities on the local reaction environment and design of catalysts for electrochemical CO2 reduction are addressed. The presented perspectives also reflect on current practices within the field and offer new opportunities for both future catalyst and system-focused research efforts.

Engineering conductive network of atomically thin bismuthene with rich defects enables CO2 reduction to formate with industry-compatible current densities and stability

2021 ◽  
Author(s):  
Min Zhang ◽  
Wenbo Wei ◽  
Shenghua Zhou ◽  
Dong-Dong Ma ◽  
Aihui Cao ◽  
...  
Keyword(s):  
Co2 Reduction ◽  
Value Added ◽  
Reduction Reaction ◽  
Conductive Network ◽  
Electrochemical Co2 Reduction ◽  
Liquid Products ◽  
Current Densities ◽  
Co2 Reduction Reaction

Electrochemical CO2 reduction reaction (CO2RR) to value-added and readily collectable liquid products is promising but remains a great challenge due to the lack of efficient and robust electrocatalysts. Herein, a...

scholarly journals Enhancing Electrocatalytic CO2 Reduction Using a System-Integrated Approach to Catalyst Discovery

2018 ◽  
Author(s):  
Thomas Burdyny ◽  
Wilson A. Smith
Keyword(s):  
Mass Transport ◽  
Electrochemical Cell ◽  
Co2 Reduction ◽  
Integrated Approach ◽  
Reduction Reaction ◽  
Reaction Conditions ◽  
Alkaline Reaction ◽  
Electrochemical Co2 Reduction ◽  
Current Densities ◽  
Co2 Reduction Reaction

The presented modelling results in this article show that electrochemical CO2 reduction performed at commercially-relevant current densities will ultimately lead to locally alkaline reaction conditions regardless of the electrolyte, configuration and reasonable mass transport scenarios. Discussed in detail are the large implications that this result has for the CO2 reduction reaction itself, and the current way in which catalysts are designed and tested in different electrochemical cell architectures.

scholarly journals Electrocatalysts derived from copper complexes transform CO into C2+ products effectively in a flow cell

2021 ◽  
Author(s):  
Shaoxuan Ren ◽  
Zishuai Zhang ◽  
Eric Lees ◽  
Arthur Fink ◽  
Luke Melo ◽  
...  
Keyword(s):  
Solid State ◽  
Copper Complexes ◽  
Copper Phthalocyanine ◽  
Product Formation ◽  
Flow Cell ◽  
Reduction Reaction ◽  
Flow Cells ◽  
New Class ◽  
Current Densities ◽  
Performance Flow

Abstract The highest performance flow cells capable of electrolytically converting CO2 into higher value chemicals and fuels pass a concentrated hydroxide electrolyte across the cathode. A major problem for CO2 electrolysis is that this strongly alkaline medium converts the majority of CO2 into unreactive HCO3– and CO32– rather than CO2 reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO2) does not suffer from this same problem because CO does not react with hydroxide. Moreover, CO can be more readily converted into products containing two or more carbon atoms (i.e., C2+ products). While several solid-state electrocatalysts have proven competent at converting CO into C2+ products, we demonstrate here that molecular electrocatalysts are also effective at mediating this transformation in a flow cell. Using a molecular copper phthalocyanine (CuPc) electrocatalyst, CO was electrolyzed into C2+ products at high rates of product formation (i.e., current densities J ≥200 mA/cm2), and at high Faradaic efficiencies for C2+ production (FEC2+; 72% at 200 mA/cm2). These findings present a new class of electrocatalysts for making carbon-neutral chemicals and fuels.

scholarly journals Improved electrochemical conversion of CO2 to multicarbon products by using molecular doping

2021 ◽  
Author(s):  
Huali WU ◽  
Ji Li ◽  
Kun Qi ◽  
Yang Zhang ◽  
Eddy Petit ◽  
...  
Keyword(s):  
High Efficiency ◽  
Reaction Pathway ◽  
Reaction Rates ◽  
Reduction Reaction ◽  
Reaction Products ◽  
Faradaic Efficiency ◽  
Cu Catalyst ◽  
Cell Energy ◽  
Current Densities ◽  
Novel Strategy

Abstract The conversion of CO2 into desirable multicarbon products such as ethylene and ethanol via the carbon dioxide reduction reaction (CO2RR) hold promise to achieve a circular carbon economy. The develop of such a technology is currently hampered by the lack of catalysts, which can drive the reaction at industrially relevant current densities with high efficiency and selectivity. Here, we report a novel strategy for increasing the conversion of CO2 into hydrocarbon molecules with two or more carbon atoms (C2+) by modifying the surface of bimetallic silver-copper (Ag-Cu) catalyst with aromatic heterocycles such as thiadiazole and triazole derivatives. By combining operando Raman and X-ray absorption spectroscopy with electrocatalytic measurements and analysis of the reaction products, we identified that the electron withdrawing nature of functional groups orients the reaction pathway towards the production of C2+ species such as ethanol and ethylene and enhances the reaction rates on the surface of the catalyst. As a result, we achieve a maximum Faradaic efficiency for the formation of C2+ of ≈ 80% and full-cell energy efficiency of 20.3% with a specific current density of 261.4 mA cm-2 for C2+ using functionalized Ag-Cu electrodes, compared to only 33.8% and 70.6 mA cm-2 for the pristine Ag-Cu electrodes. We anticipate that our strategy can further be extended in order to improve the selectivity of the reaction towards the production of specific multicarbon molecules.

scholarly journals Visualisation and quantification of flooding phenomena in gas diffusion electrodes (GDEs) used for electrochemical CO2 reduction: A combined EDX/ICP–MS approach

2022 ◽  
Author(s):  
Ying Kong ◽  
Huifang Hu ◽  
Menglong Liu ◽  
Yuhui Hou ◽  
Viliam Kolivoska ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Co2 Reduction ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Gas Diffusion Electrodes ◽  
Cross Sectional ◽  
Faradaic Efficiency ◽  
Icp Ms ◽  
Electrochemical Co2 Reduction ◽  
Current Densities

The most promising strategy to up-scale the electrochemical CO2 reduction reaction (ec-CO2RR) is based on the use of gas diffusion electrodes (GDEs) that allow current densities close to the range of 1 A/cm2 to be reached. At such high current densities, however, the flooding of the GDE cathode is often observed in CO2 electrolysers. Flooding hinders the access of CO2 to the catalyst, and by thus leaving space for (unwanted) hydrogen evolution, it usually leads to a decrease of the observable Faradaic efficiency of CO2 reduction products. To avoid flooding as much as possible has thus become one of the most important aims of to-date ec-CO2RR engineering, and robust analytical methods that can quantitatively assess flooding are now in demand. As flooding is very closely related to the formation of carbonate salts within the GDE structure, in this paper we use alkali (in particular, potassium) carbonates as a tracer of flooding. We present a novel analytical approach —based on the combination of cross-sectional energy-dispersive X-ray (EDX) mapping and inductively coupled plasma mass spectrometry (ICP--MS) analysis— that can not only visualise, but can also quantitatively describe the electrolysis time dependent flooding in GDEs, leading to a better understanding of electrolyser malfunctions.

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