scholarly journals Understanding the electric and nonelectric field components of the cation effect on the electrochemical CO reduction reaction

2020 ◽  
Vol 6 (45) ◽  
pp. eabd2569 ◽  
Author(s):  
A. S. Malkani ◽  
J. Li ◽  
N. J. Oliveira ◽  
M. He ◽  
X. Chang ◽  
...  
Keyword(s):  
Field Strength ◽  
Hydration Shell ◽  
Reduction Reaction ◽  
Cation Effect ◽  
Spectroscopic Investigations ◽  
Composition And Structure ◽  
Electrochemical Interface ◽  
Alkaline Electrolytes ◽  
Modes Of Interaction ◽  
Co Reduction

Electrolyte cations affect the activity of surface-mediated electrocatalytic reactions; however, understanding the modes of interaction between cations and reaction intermediates remains lacking. We show that larger alkali metal cations (excluding the thickness of the hydration shell) promote the electrochemical CO reduction reaction on polycrystalline Cu surfaces in alkaline electrolytes. Combined reactivity and in situ surface-enhanced spectroscopic investigations show that changes to the interfacial electric field strength cannot solely explain the reactivity trend with cation size, suggesting the presence of a nonelectric field strength component in the cation effect. Spectroscopic investigations with cation chelating agents and organic molecules show that the electric and nonelectric field components of the cation effect could be affected by both cation identity and composition of the electrochemical interface. The interdependent nature of interfacial species indicates that the cation effect should be considered an integral part of the broader effect of composition and structure of the electrochemical interface on electrode-mediated reactions.

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions

2019 ◽  
Author(s):  
Jack Pedersen ◽  
Thomas Batchelor ◽  
Alexander Bagger ◽  
Jan Rossmeisl
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Hydrogen Adsorption ◽  
Co Adsorption ◽  
Reduction Reaction ◽  
Supervised Machine Learning ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Co Reduction ◽  
Disordered Alloy

Using the high-entropy alloys (HEAs) CoCuGaNiZn and AgAuCuPdPt as starting points we provide a framework for tuning the composition of disordered multi-metallic alloys to control the selectivity and activity of the reduction of carbon dioxide (CO2) to highly reduced compounds. By combining density functional theory (DFT) with supervised machine learning we predicted the CO and hydrogen (H) adsorption energies of all surface sites on the (111) surface of the two HEAs. This allowed an optimization for the HEA compositions with increased likelihood for sites with weak hydrogen adsorption{to suppress the formation of molecular hydrogen (H2) and with strong CO adsorption to favor the reduction of CO. This led to the discovery of several disordered alloy catalyst candidates for which selectivity towards highly reduced carbon compounds is expected, as well as insights into the rational design of disordered alloy catalysts for the CO2 and CO reduction reaction.

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

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.

Trimetallic PtNiCo branched nanocages as efficient and durable bifunctional electrocatalysts towards oxygen reduction and methanol oxidation reactions

2021 ◽  
Author(s):  
hengrui Ma ◽  
Zhiping Zheng ◽  
Hongsheng Zhao ◽  
Cong Shen ◽  
Hanming Chen ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Methanol Oxidation ◽  
Oxidation Reaction ◽  
Reduction Reaction ◽  
Great Promise ◽  
Methanol Oxidation Reaction ◽  
Oxidation Reactions ◽  
Bifunctional Electrocatalysts ◽  
Composition And Structure

Engineering the composition and structure of Pt-based alloy electrocatalysts has exhibited great promise for enhancing activity and durability in oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). However, it...

scholarly journals Electrochemical CO Reduction: A Property of the Electrochemical Interface

2019 ◽  
Vol 141 (4) ◽  
pp. 1506-1514 ◽  
Author(s):  
Alexander Bagger ◽  
Logi Arnarson ◽  
Martin H. Hansen ◽  
Eckhard Spohr ◽  
Jan Rossmeisl
Keyword(s):  
Electrochemical Interface ◽  
Co Reduction

An MOF-derived C@NiO@Ni electrocatalyst for N2 conversion to NH3 in alkaline electrolytes

2020 ◽  
Vol 4 (1) ◽  
pp. 164-170 ◽  
Author(s):  
Shijian Luo ◽  
Xiaoman Li ◽  
Wanguo Gao ◽  
Haiqiang Zhang ◽  
Min Luo
Keyword(s):  
Active Sites ◽  
Oxygen Vacancies ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Alkaline Electrolytes

MOF-derived C@NiO@Ni are proposed as an efficient electrocatalyst for N2 reduction reaction in alkaline media. Abundant oxygen vacancies and NiO/Ni interfaces can act as active sites for adsorbing nitrogen and proton, respectively.

Impact of Forced Convection on Spectroscopic Observations of the Electrochemical CO Reduction Reaction

ACS Catalysis ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 941-946 ◽  
Author(s):  
Arnav S. Malkani ◽  
Jing Li ◽  
Jacob Anibal ◽  
Qi Lu ◽  
Bingjun Xu
Keyword(s):  
Forced Convection ◽  
Reduction Reaction ◽  
Spectroscopic Observations ◽  
Co Reduction

Screen-Printing-Based Fabrication of Silver Patterns on Polyimide Substrate

2012 ◽  
Vol 510 ◽  
pp. 176-181 ◽  
Author(s):  
Fang Yang ◽  
Wei Su ◽  
Li Bei Yao ◽  
Li Fang Liang ◽  
Yu Xin Liu ◽  
...  
Keyword(s):  
Screen Printing ◽  
Substrate Surface ◽  
Silver Ions ◽  
Reduction Reaction ◽  
Contact Angles ◽  
Simple Method ◽  
Ion Exchange Reaction ◽  
Composition And Structure ◽  
Dimethylamine Borane ◽  
Ft Ir

A simple method for fabricating silver circuit patterns on polyimide (PI) substrate was developed. Firstly, partially potassium hydroxide (KOH) modified pattern was produced on the surface of PI film via a screen printing process. Then the silver ions were doped into the interior of the PI substrate through an ion-exchange reaction. Finally, the silver circuit patterns with the lines of 200 µm width were formed on the PI substrate surface due to the reduction reaction of dimethylamine borane (DMAB). Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, infrared spectra (FT-IR) and contact angles analyses were conducted to study the morphology, composition and structure of the obtained silver patterns on the PI substrate. This approach is simple and versatile, and need not the expensive apparatus, which is a promising candidate for a broad range of application in high-density circuitry electronic industry.

scholarly journals Co-Zn-MOFs Derived N-Doped Carbon Nanotubes with Crystalline Co Nanoparticles Embedded as Effective Oxygen Electrocatalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 261
Author(s):  
Wendi Zhang ◽  
Xiaoming Liu ◽  
Man Gao ◽  
Hong Shang ◽  
Xuanhe Liu
Keyword(s):  
Carbon Nanotubes ◽  
Low Cost ◽  
Three Dimensional ◽  
Reduction Reaction ◽  
Hydrogen Electrode ◽  
New Strategy ◽  
Different Temperatures ◽  
Alkaline Electrolytes ◽  
Electron Migration ◽  
Co Nanoparticles

The oxygen reduction reaction (ORR) is a crucial step in fuel cells and metal-air batteries. It is necessary to expand the range of efficient non-precious ORR electrocatalysts on account of the low abundance and high cost of Pt/C catalysts. Herein, we synthesized crystalline cobalt-embedded N-doped carbon nanotubes (Co@CNTs-T) via facile carbonization of Co/Zn metal-organic frameworks (MOFs) with dicyandiamide at different temperatures (t = 600, 700, 800, 900 °C). Co@CNTs- 800 possessed excellent ORR activities in alkaline electrolytes with a half wave potential of 0.846 V vs. RHE (Reversible Hydrogen Electrode), which was comparable to Pt/C. This three-dimensional network, formed by Co@CNTs-T, facilitated electron migration and ion diffusion during the ORR process. The carbon shell surrounding the Co nanoparticles resulted in Co@CNTs-800 being stable as an electrocatalyst. This work provides a new strategy to design efficient and low-cost oxygen catalysts.

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