scholarly journals Enhanced Electrocatalytic CO2 Reduction at Lower Overpotentials Using Iron (III) Tetra(thienyl)porphyrin

2019 ◽  
Author(s):  
Josh D. B. Koenig ◽  
Janina Willkomm ◽  
Roland Roesler ◽  
Warren Piers ◽  
Gregory C. Welch
Keyword(s):  
Electrochemical Properties ◽  
Co2 Reduction ◽  
Faradaic Efficiency ◽  
Lower Overpotential

Iron(III) tetra(5,10,15,20-thienyl)porphyrin chloride (FeTThP) is introduced as a new CO<sub>2</sub> reduction catalyst. The optical and electrochemical properties, as well as the CO<sub>2</sub> reduction capabilities of FeTThP are directly compared to those of iron(III) tetra(5,10,15,20-phenyl)porphyrin chloride (FeTPP). Relative to FeTPP, the newly developed FeTThP achieves a higher TON<sub>CO</sub>, with comparable faradaic efficiency, using a much lower overpotential.

scholarly journals Quasi-graphitic carbon shell-induced Cu confinement promotes electrocatalytic CO2 reduction toward C2+ products

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ji-Yong Kim ◽  
Deokgi Hong ◽  
Jae-Chan Lee ◽  
Hyoung Gyun Kim ◽  
Sungwoo Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Co2 Reduction ◽  
Value Added ◽  
Material Design ◽  
Catalyst System ◽  
Critical Issue ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Design Strategies ◽  
Faradaic Efficiency

AbstractFor steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

scholarly journals A high throughput optical method for studying compositional effects in electrocatalysts for CO2 reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jeremy L. Hitt ◽  
Yuguang C. Li ◽  
Songsheng Tao ◽  
Zhifei Yan ◽  
Yue Gao ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
High Throughput ◽  
High Throughput Screening ◽  
Screening Method ◽  
Co2 Reduction ◽  
Fold Increase ◽  
Faradaic Efficiency ◽  
Atomic Pair Distribution Function ◽  
Earth Abundant ◽  
Ternary Catalysts

AbstractIn the problem of electrochemical CO2 reduction, the discovery of earth-abundant, efficient, and selective catalysts is essential to enabling technology that can contribute to a carbon-neutral energy cycle. In this study, we adapt an optical high throughput screening method to study multi-metallic catalysts for CO2 electroreduction. We demonstrate the utility of the method by constructing catalytic activity maps of different alloyed elements and use X-ray scattering analysis by the atomic pair distribution function (PDF) method to gain insight into the structures of the most active compositions. Among combinations of four elements (Au, Ag, Cu, Zn), Au6Ag2Cu2 and Au4Zn3Cu3 were identified as the most active compositions in their respective ternaries. These ternary electrocatalysts were more active than any binary combination, and a ca. 5-fold increase in current density at potentials of −0.4 to −0.8 V vs. RHE was obtained for the best ternary catalysts relative to Au prepared by the same method. Tafel plots of electrochemical data for CO2 reduction and hydrogen evolution indicate that the ternary catalysts, despite their higher surface area, are poorer catalysts for the hydrogen evolution reaction than pure Au. This results in high Faradaic efficiency for CO2 reduction to CO.

scholarly journals CuZnAl-Oxide Nanopyramidal Mesoporous Materials for the Electrocatalytic CO2 Reduction to Syngas: Tuning of H2/CO Ratio

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3052
Author(s):  
Hilmar Guzmán ◽  
Daniela Roldán ◽  
Adriano Sacco ◽  
Micaela Castellino ◽  
Marco Fontana ◽  
...  
Keyword(s):  
Noble Metals ◽  
Co2 Reduction ◽  
Reduction Process ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
H2 Production ◽  
Ambient Conditions ◽  
Transfer Resistance ◽  
Faradaic Efficiency ◽  
Co2 Electroreduction

Inspired by the knowledge of the thermocatalytic CO2 reduction process, novel nanocrystalline CuZnAl-oxide based catalysts with pyramidal mesoporous structures are here proposed for the CO2 electrochemical reduction under ambient conditions. The XPS analyses revealed that the co-presence of ZnO and Al2O3 into the Cu-based catalyst stabilize the CuO crystalline structure and introduce basic sites on the ternary as-synthesized catalyst. In contrast, the as-prepared CuZn- and Cu-based materials contain a higher amount of superficial Cu0 and Cu1+ species. The CuZnAl-catalyst exhibited enhanced catalytic performance for the CO and H2 production, reaching a Faradaic efficiency (FE) towards syngas of almost 95% at −0.89 V vs. RHE and a remarkable current density of up to 90 mA cm−2 for the CO2 reduction at −2.4 V vs. RHE. The physico-chemical characterizations confirmed that the pyramidal mesoporous structure of this material, which is constituted by a high pore volume and small CuO crystals, plays a fundamental role in its low diffusional mass-transfer resistance. The CO-productivity on the CuZnAl-catalyst increased at more negative applied potentials, leading to the production of syngas with a tunable H2/CO ratio (from 2 to 7), depending on the applied potential. These results pave the way to substitute state-of-the-art noble metals (e.g., Ag, Au) with this abundant and cost-effective catalyst to produce syngas. Moreover, the post-reaction analyses demonstrated the stabilization of Cu2O species, avoiding its complete reduction to Cu0 under the CO2 electroreduction conditions.

CO2 reduction to formic acid at low overpotential on BDD electrodes modified with nanostructured CeO2

2019 ◽  
Vol 7 (30) ◽  
pp. 17896-17905 ◽  
Author(s):  
Enrico Verlato ◽  
Simona Barison ◽  
Yasuaki Einaga ◽  
Stefano Fasolin ◽  
Marco Musiani ◽  
...  
Keyword(s):  
Formic Acid ◽  
Co2 Reduction ◽  
Faradaic Efficiency ◽  
Low Overpotential

Nanostructured CeO2/BDD electrodes produce formic acid with good faradaic efficiency at very low overpotential (>40% at η ≈ 40 mV).

Electrochemical Properties and CO2-Reduction Ability of m-Terphenyl Isocyanide Supported Manganese Tricarbonyl Complexes

2016 ◽  
Vol 55 (23) ◽  
pp. 12400-12408 ◽  
Author(s):  
Douglas W. Agnew ◽  
Matthew D. Sampson ◽  
Curtis E. Moore ◽  
Arnold L. Rheingold ◽  
Clifford P. Kubiak ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Co2 Reduction ◽  
Manganese Tricarbonyl

scholarly journals An Iron Pyridyl-Carbene Catalyst for Low Overpotential CO2 reduction to CO: Mechanistic Comparisons with the Ruthenium Analogue and Photochemical Promotion

2020 ◽  
Author(s):  
Sergio Gonell ◽  
Julio Lloret ◽  
Alexander Miller
Keyword(s):  
Co2 Reduction ◽  
Iron Complexes ◽  
Transition Metal Ions ◽  
Ruthenium Catalysts ◽  
Computational Studies ◽  
Chelating Ligands ◽  
Faradaic Efficiency ◽  
Mechanistic Insight ◽  
Redox Active ◽  
Improved Performance

<div><div><div><p>Electrocatalysts for CO2 reduction based on first row transition metal ions have attracted attention as abundant and affordable candidates for energy conversion applications. We hypothesized that a successful strategy in ruthenium electrocatalyst design, featuring two chelating ligands that can be individually tuned to adjust the overpotential and catalytic activity, could be equally applicable in the analogous iron complexes. New iron complexes supported by a redox-active 2,2':6',2''-terpyridine (tpy) ligand and strong trans effect pyridyl- N-heterocyclic carbene ligand (1-methyl-benzimidazol-2-ylidene-3-(2-pyridine)) were synthesized, and these isostructural analogues to leading ruthenium catalysts were also found to be active CO2 reduction electrocatalysts. Electrochemical and computational studies reveal completely distinct mechanisms for the iron and ruthenium complexes, with hemilability in the iron system enabling electrocatalysis at overpotentials as low as 150 mV (ca. 500 mV lower than the ruthenium analogue). Cyclic voltammetry studies elucidated the mechanism of the net 4e–/2H+ process that occurs within the single reductive feature, with an iron solvento complex undergoing reduction, CO2 activation, and further reduction to an iron carbonyl. The mechanistic insight guided development of photoelectrocatalytic conditions under a continuous flow of CO2 that exhibited improved performance, with Faradaic efficiency up to 99%.</p></div></div></div>

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.

scholarly journals Breaking Scaling Relationships in CO2 Reduction on Copper Alloys with Organic Additives

2021 ◽  
Author(s):  
Yunchieh Lai ◽  
Nicholas Watkins ◽  
Alonso Rosas-Hernández ◽  
Arnaud Thevenon ◽  
Gavin P. Heim ◽  
...  
Keyword(s):  
Copper Alloys ◽  
Co2 Reduction ◽  
Product Formation ◽  
Organic Additives ◽  
Faradaic Efficiency ◽  
Scaling Relationships ◽  
Linear Free Energy ◽  
High Throughput Experimentation ◽  
Scaling Relationship ◽  
Carbon Economy

<p>Boundary conditions for catalyst performance in the conversion of common precursors such as N<sub>2</sub>, O<sub>2</sub>, H<sub>2</sub>O, and CO<sub>2</sub> are governed by linear free energy and scaling relationships. Knowledge of these limits offers an impetus for designing strategies to alter reaction mechanisms to improve performance. Towards a more sustainable carbon economy, understanding the basis of catalytic selectivity for CO<sub>2</sub> conversion to chemical feedstocks/fuels is key. Herein, high-throughput experimentation on 14 bulk copper bimetallic alloys allowed for data-driven identification of a fundamental linear scaling relationship between methane and C<sub>2+</sub> products that constrains the Faradaic efficiency for C–C coupling. We have furthermore demonstrated that coating the electrodes with a molecular film breaks the scaling relationship to promote C<sub>2+</sub> product formation.</p>

Electrochemical CO2 reduction to methane with remarkably high Faradaic efficiency in the presence of a proton permeable membrane

2020 ◽  
Vol 13 (10) ◽  
pp. 3567-3578 ◽  
Author(s):  
Hanqing Pan ◽  
Christopher J. Barile
Keyword(s):  
Co2 Reduction ◽  
Permeable Membrane ◽  
Faradaic Efficiency ◽  
Electrochemical Co2 Reduction

Cu electrodes modified with a Nafion layer catalyze the reduction of CO2 to CH4 with up to 88% Faradaic efficiency.

scholarly journals Photoelectrochemical Reduction of CO2 to Syngas by Reduced Ag Catalysts on Si Photocathodes

2020 ◽  
Vol 10 (10) ◽  
pp. 3487 ◽  
Author(s):  
Changyeon Kim ◽  
Seokhoon Choi ◽  
Min-Ju Choi ◽  
Sol A Lee ◽  
Sang Hyun Ahn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Co2 Reduction ◽  
Reduction Reaction ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
Onset Potential ◽  
Reduction Of Co2 ◽  
Co2 Reduction Reaction ◽  
Ag Catalysts

The photoelectrochemical reduction of CO2 to syngas that is used for many practical applications has been emerging as a promising technique to relieve the increase of CO2 in the atmosphere. Si has been considered to be one of the most promising materials for photoelectrodes, but the integration of electrocatalysts is essential for the photoelectrochemical reduction of CO2 using Si. We report an enhancement of catalytic activity for CO2 reduction reaction by Ag catalysts of tuned morphology, active sites, and electronic structure through reducing anodic treatment. Our proposed photocathode structure, a SiO2 patterned p-Si photocathode with these reduced Ag catalysts, that was fabricated using electron-beam deposition and electrodeposition methods, provides a low onset-potential of −0.16 V vs. the reversible hydrogen electrode (RHE), a large saturated photocurrent density of −9 mA/cm2 at −1.23 V vs. RHE, and faradaic efficiency for CO of 47% at −0.6 V vs. RHE. This photocathode can produce syngas in the ratio from 1:1 to 1:3, which is an appropriate proportion for practical application. This work presents a new approach for designing photocathodes with a balanced catalytic activity and light absorption to improve the photoelectrochemical application for not only CO2 reduction reaction, but also water splitting or N2 reduction reaction.

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