scholarly journals Electrochemical CO2 Reduction on Nanostructured Metal Electrodes: Fact or Defect?

2019 ◽  
Author(s):  
Recep Kas ◽  
Kailun Yang ◽  
Divya Bohra ◽  
Ruud Kortlever ◽  
Thomas Burdyny ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Structural Changes ◽  
Co2 Reduction ◽  
Catalyst Layer ◽  
Active Surface ◽  
Process Conditions ◽  
Active Surface Area ◽  
Catalytic Layer ◽  
Nanostructured Electrodes ◽  
Electrochemical Co2 Reduction

<div> <p>Electrochemical CO<sub>2</sub> reduction has received an increased amount of interest in the last decade as a promising avenue for storing renewable electricity in chemical bonds. Despite considerable progress on catalyst performance using nanostructured electrodes, the sensitivity of the reaction to process conditions has led to debate on the origin of the activity and high selectivity. Additionally, this raises questions on the transferability of the performance and knowledge to other electrochemical systems. At its core, the discrepancy is primarily a result of the highly porous nature of nanostructured electrodes, which are vulnerable to both mass transport effects and structural changes during the electrolysis. Both effects are not straightforward to identify and difficult to decouple. Despite the susceptibility of nanostructured electrodes to mass transfer limitations, we highlight that nanostructured silver electrodes exhibit considerably higher activity when normalized to the electrochemically active surface in contrast to gold and copper electrodes. Alongside, we provide a discussion on how active surface area and thickness of the catalytic layer itself can influence the selectivity, stability, activity and mass transfer inside and outside of the three dimensional catalyst layer. Key parameters and potential solutions are highlighted to decouple mass transfer effects from the measured activity in electrochemical cells utilizing CO<sub>2</sub> saturated aqueous solutions. </p> </div> <br>

scholarly journals Electrochemical CO2 Reduction on Nanostructured Metal Electrodes: Fact or Defect?

2019 ◽  
Author(s):  
Recep Kas ◽  
Kailun Yang ◽  
Divya Bohra ◽  
Ruud Kortlever ◽  
Thomas Burdyny ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Structural Changes ◽  
Co2 Reduction ◽  
Catalyst Layer ◽  
Active Surface ◽  
Process Conditions ◽  
Active Surface Area ◽  
Catalytic Layer ◽  
Nanostructured Electrodes ◽  
Electrochemical Co2 Reduction

<div> <p>Electrochemical CO<sub>2</sub> reduction has received an increased amount of interest in the last decade as a promising avenue for storing renewable electricity in chemical bonds. Despite considerable progress on catalyst performance using nanostructured electrodes, the sensitivity of the reaction to process conditions has led to debate on the origin of the activity and high selectivity. Additionally, this raises questions on the transferability of the performance and knowledge to other electrochemical systems. At its core, the discrepancy is primarily a result of the highly porous nature of nanostructured electrodes, which are vulnerable to both mass transport effects and structural changes during the electrolysis. Both effects are not straightforward to identify and difficult to decouple. Despite the susceptibility of nanostructured electrodes to mass transfer limitations, we highlight that nanostructured silver electrodes exhibit considerably higher activity when normalized to the electrochemically active surface in contrast to gold and copper electrodes. Alongside, we provide a discussion on how active surface area and thickness of the catalytic layer itself can influence the selectivity, stability, activity and mass transfer inside and outside of the three dimensional catalyst layer. Key parameters and potential solutions are highlighted to decouple mass transfer effects from the measured activity in electrochemical cells utilizing CO<sub>2</sub> saturated aqueous solutions. </p> </div> <br>

scholarly journals Electrochemical Reduction of CO2 to CO on Hydrophobic Zn Foam Rod in a Microchannel Electrochemical Reactor

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1592
Author(s):  
Chunxiao Zhang ◽  
Shenglin Yan ◽  
Jing Lin ◽  
Qing Hu ◽  
Juhua Zhong ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Saturated Calomel Electrode ◽  
Co2 Reduction ◽  
Active Surface ◽  
Active Surface Area ◽  
Mass Transfer Limitation ◽  
Faradaic Efficiency ◽  
Electrochemical Co2 Reduction ◽  
Hydrophobic Layer ◽  
Co2 Mass Transfer

Due to CO2 mass transfer limitation as well as the competition of hydrogen evolution reaction in electroreduction of CO2 in the aqueous electrolyte, Zn-based electrodes normally exhibit unsatisfying selectivity for CO production, especially at high potentials. In this work, we introduced a zinc myristate (Zn [CH3(CH2)12COO]2) hydrophobic layer on the surface of zinc foam electrode by an electrodeposition method. The obtained hydrophobic zinc foam electrode showed a high Faradaic efficiency (FE) of 91.8% for CO at −1.9 V (vs. saturated calomel electrode, SCE), which was a remarkable improvement over zinc foam (FECO = 81.87%) at the same potentials. The high roughness of the hydrophobic layer has greatly increased the active surface area and CO2 mass transfer performance by providing abundant gas-liquid-solid contacting area. This work shows adding a hydrophobic layer on the surface of the catalyst is an effective way to improve the electrochemical CO2 reduction performance.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

scholarly journals High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6357
Author(s):  
Roberto Luigi Oliveri ◽  
Maria Grazia Insinga ◽  
Simone Pisana ◽  
Bernardo Patella ◽  
Giuseppe Aiello ◽  
...  
Keyword(s):  
High Performance ◽  
Active Material ◽  
Active Surface ◽  
Effect Of Temperature ◽  
Active Surface Area ◽  
Polycarbonate Membrane ◽  
Nanostructured Electrodes ◽  
Lead Acid Batteries ◽  
Improved Stability ◽  
Lead Acid

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electrodes. In particular, we have obtained nanostructured electrodes in Pb and PbO2 through electrosynthesis in a template consisting of a nanoporous polycarbonate membrane. These electrodes are characterized by a wider active surface area, which allows for a better use of the active material, and for a consequent increased specific energy compared to traditional batteries. In this research, the performance of lead-acid batteries with nanostructured electrodes was studied at 10 C at temperatures of 25, −20 and 40 °C in order to evaluate the efficiency and the effect of temperature on electrode morphology. The batteries were assembled using both nanostructured electrodes and an AGM-type separator used in commercial batteries.

Effect of mass transfer and kinetics in ordered Cu-mesostructures for electrochemical CO2 reduction

2018 ◽  
Vol 232 ◽  
pp. 391-396 ◽  
Author(s):  
Hakhyeon Song ◽  
Mintaek Im ◽  
Jun Tae Song ◽  
Jung-Ae Lim ◽  
Beom-Sik Kim ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Co2 Reduction ◽  
Electrochemical Co2 Reduction

scholarly journals Optimizing the use of a “Zero-Gap” Gas Diffusion Electrode Setup for Electrochemical Reduction of CO2

2021 ◽  
Author(s):  
Shima Alinejad ◽  
Jonathan Quinson ◽  
Yao Li ◽  
Ying Kong ◽  
Sven Reichenberger ◽  
...  
Keyword(s):  
Co2 Reduction ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Gas Diffusion Electrode ◽  
Test Bed ◽  
Catalyst Screening ◽  
Electrochemical Co2 Reduction ◽  
Reduction Of Co2 ◽  
Co2 Reduction Reaction

The lack of a robust and standardized experimental test bed to investigate the performance of catalyst materials for the electrochemical CO2 reduction reaction (ECO2RR) is one of the major challenges in this field of research. To best reproduce and mimic commercially relevant conditions for catalyst screening and testing, gas diffusion electrode (GDE) setups attract a rising attention as an alternative to conventional aqueous-based setups such as the H-cell configuration. In particular a zero-gap design shows promising features for upscaling to the commercial scale. In this study, we develop further our recently introduced zero-gap GDE setup for the CO2RR using an Au electrocatalyst as model system and identify/report the key experimental parameters to control in the catalyst layer preparation in order to optimize the activity and selectivity of the catalyst.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

Utilization of the catalyst layer of dimensionally stable anodes—Interplay of morphology and active surface area

2012 ◽  
Vol 82 ◽  
pp. 408-414 ◽  
Author(s):  
Aleksandar R. Zeradjanin ◽  
Fabio La Mantia ◽  
Justus Masa ◽  
Wolfgang Schuhmann
Keyword(s):  
Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
Dimensionally Stable Anodes

scholarly journals Sputtered highly effective iridium catalysts: a new approach for green satellite propulsion

2021 ◽  
Vol 56 (16) ◽  
pp. 9974-9984
Author(s):  
Manfred Stollenwerk ◽  
Tobias Schäfer ◽  
Johannes Stadtmüller ◽  
Thorsten Döhring ◽  
Dominic Freudenmann ◽  
...  
Keyword(s):  
First Generation ◽  
Active Surface ◽  
Open Shell ◽  
Process Conditions ◽  
Active Surface Area ◽  
Zone Model ◽  
Space Propulsion ◽  
Iridium Catalysts ◽  
New Approach ◽  
Process Pressure

AbstractThis work demonstrated the large potential of sputtered iridium metal for catalytic reactions shown by the example of decomposition of hydrogen peroxide (H2O2) for space propulsion systems. For this purpose, iridium was coated onto Al2O3 pellets by a sputter process under varied process parameters. Depending on previously selected parameters, the obtained metal-loaded pellets offer closed- and/or open-shell structures. Catalytic productivity of these first-generation iridium-sputtered catalysts was estimated in laboratory experiments and compared to platinum-loaded pellets. Under optimized sputter-process conditions, the reactivity is significantly improved compared to the platinum-impregnated pellets. The better catalytic productivity can be explained by the increased active surface area of the iridium layers on the pellets. The surface morphology and the microstructure of the iridium coating can be actively controlled by the sputter pressure. The results are in accordance with the sputtering process pressure tendency described by the Thornton Structure–Zone Model. Graphical abstract

scholarly journals Synthesis of MWCNT Forests with Alumina-Supported Fe2O3 Catalyst by Using a Floating Catalyst Chemical Vapor Deposition Technique

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Shazia Shukrullah ◽  
Muhammad Y. Naz ◽  
Norani M. Mohamed ◽  
Khalid A. Ibrahim ◽  
Abdul Ghaffar ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Active Surface ◽  
Metal Catalyst ◽  
Process Conditions ◽  
Active Surface Area ◽  
Alumina Support ◽  
Vapor Deposition Technique ◽  
Catalyst Chemical Vapor Deposition

In this study, multiwalled CNT bundles were synthesized with an alumina-supported Fe2O3 catalyst by using a floating catalyst chemical vapor deposition (FCCVD) technique. The metal catalyst was synthesized by dispersing Fe2O3 on alumina support. Ethylene molecules were decomposed over different amounts of metal nanoparticles in a FCCVD reactor. The CVD temperature was elevated from 600°C to 1000°C. The large active surface area of the metal nanobuds promoted the decomposition of a carbon precursor and the fast growth of CNT bundles. Least dense bundles of varying heights were observed at lower CVD temperatures of 600°C and 700°C. At 800°C, CVD process conditions were found suitable for the fast decomposition of hydrocarbon. The relatively better yield of well-structured CNTs was obtained with a catalyst weight of 0.3 g at 800°C. Above 800°C, CNT forests start losing alignment and height. The forest density was also decreased at temperatures above the optimum. The elemental composition of CNT bundles revealed the presence of carbon, aluminium, oxygen, and iron in percentages of 91%, 0.76%, 8.2%, and 0.04%, respectively. A very small ID to IG ratio of 0.22 was calculated for CNTs grown under optimized conditions.

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