scholarly journals Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

2021 ◽  
Author(s):  
Siddhartha Subramanian ◽  
Joost Middelkoop ◽  
Thomas Burdyny
Keyword(s):  
Value Added ◽  
Catalytic Performance ◽  
Process Performance ◽  
Co2 Utilization ◽  
Faradaic Efficiency ◽  
Co2 Electrolysis ◽  
Reactant Distribution

The production of value added C1 and C2 compounds within CO2 electrolyzers has reached sufficient catalytic performance that system and process performance – such as CO2 utilization – have come...

scholarly journals Spatial reactant distribution in CO2 electrolysis: Balancing CO2 utilization and Faradaic Efficiency

2021 ◽  
Author(s):  
Siddhartha Subramanian ◽  
Joost Middelkoop ◽  
Thomas Burdyny
Keyword(s):  
Value Added ◽  
Membrane Electrode Assembly ◽  
Catalytic Performance ◽  
Membrane Electrode ◽  
Co2 Utilization ◽  
Faradaic Efficiency ◽  
Gas Channel ◽  
Spatially Resolved ◽  
Diffusion Layers ◽  
Trade Offs

The production of value added C1 and C2 compounds within CO2 electrolyzers has reached sufficient catalytic performance that system and process performance – such as CO2 utilization – have come more into consideration. Efforts to assess the limitations of CO2 conversion and crossover within electrochemical systems have been performed, providing valuable information to position CO2 electrolyzers within a larger process. Currently missing, however, is a clear elucidation of the inevitable trade-offs that exist between CO2 utilization and electrolyzer performance, specifically how the Faradaic Efficiency of a system varies with CO2 availability. Such information is needed to properly assess the viability of the technology. In this work, we provide a combined experimental and 3D modelling assessment of the trade-offs between CO2 utilization and selectivity at 200 mA/cm2 within a membrane-electrode assembly CO2 electrolyzer. Using varying inlet flow rates we demonstrate that the variation in spatial concentration of CO2 leads to spatial variations in Faradaic Efficiency that cannot be captured using common ‘black box’ measurement procedures. Specifically, losses of Faradaic efficiency are observed to occur even at incomplete CO2 consumption (80%). Modelling of the gas channel and diffusion layers indicated at least a portion of the H2 generated is considered as avoidable by proper flow field design and modification. The combined work allows for a spatially resolved interpretation of product selectivity occurring inside the reactor, providing the foundation for design rules in balancing CO2 utilization and device performance in both lab and scaled applications.

scholarly journals Efficient Electrochemical Reduction of CO2 to CO in Ionic Liquid/Propylene Carbonate Electrolyte on Ag Electrode

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1102
Author(s):  
Fengyang Ju ◽  
Jinjin Zhang ◽  
Weiwei Lu
Keyword(s):  
Ionic Liquids ◽  
Electrochemical Reduction ◽  
Propylene Carbonate ◽  
Value Added ◽  
Catalytic Performance ◽  
Co2 Conversion ◽  
Imidazolium Cation ◽  
Faradaic Efficiency ◽  
Ag Electrode ◽  
Reduction Of Co2

The electrochemical reduction of CO2 is a promising way to recycle it to produce value-added chemicals and fuels. However, the requirement of high overpotential and the low solubility of CO2 in water severely limit their efficient conversion. To overcome these problems, in this work, a new type of electrolyte solution constituted by ionic liquids and propylene carbonate was used as the cathodic solution, to study the conversion of CO2 on an Ag electrode. The linear sweep voltammetry (LSV), Tafel characterization and electrochemical impedance spectroscopy (EIS) were used to study the catalytic effect and the mechanism of ionic liquids in electrochemical reduction of CO2. The LSV and Tafel characterization indicated that the chain length of 1-alkyl-3-methyl imidazolium cation had strong influences on the catalytic performance for CO2 conversion. The EIS analysis showed that the imidazolium cation that absorbed on the Ag electrode surface could stabilize the anion radical (CO2•−), leading to the enhanced efficiency of CO2 conversion. At last, the catalytic performance was also evaluated, and the results showed that Faradaic efficiency for CO as high as 98.5% and current density of 8.2 mA/cm2 could be achieved at −1.9 V (vs. Fc/Fc+).

Graphdiyne Anchored Ultrafine Ag Nanoparticles for High Efficient and Solvent-Free Catalysis of CO2 Cycloaddition

2021 ◽  
Author(s):  
Chang Liu ◽  
Chao Zhang ◽  
Tongbu Lu
Keyword(s):  
Ag Nanoparticles ◽  
Co2 Reduction ◽  
Value Added ◽  
Solvent Free ◽  
Alternative Route ◽  
Practical Application ◽  
Co2 Utilization ◽  
High Efficient

Apart from photo-/electro-catalytic CO2 reduction, an important alternative route to CO2 utilization is to use this inert molecule as a C1 source to synthesize value-added chemicals, while the practical application...

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 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.

scholarly journals Synthesis and characterization of rice husk biochar via hydrothermal carbonization for wastewater treatment and biofuel production

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nazia Hossain ◽  
Sabzoi Nizamuddin ◽  
Gregory Griffin ◽  
Periasamy Selvakannan ◽  
Nabisab Mujawar Mubarak ◽  
...  
Keyword(s):  
Rice Husk ◽  
Agricultural Waste ◽  
Value Added ◽  
Hydrothermal Carbonization ◽  
Catalytic Performance ◽  
Biofuel Production ◽  
Suspension Stability ◽  
Waste Biomass ◽  
Suitable Material ◽  
Rice Husk Biochar

Abstract The recent implication of circular economy in Australia spurred the demand for waste material utilization for value-added product generations on a commercial scale. Therefore, this experimental study emphasized on agricultural waste biomass, rice husk (RH) as potential feedstock to produce valuable products. Rice husk biochar (RB) was obtained at temperature: 180 °C, pressure: 70 bar, reaction time: 20 min with water via hydrothermal carbonization (HTC), and the obtained biochar yield was 57.9%. Enhancement of zeta potential value from − 30.1 to − 10.6 mV in RB presented the higher suspension stability, and improvement of surface area and porosity in RB demonstrated the wastewater adsorption capacity. Along with that, an increase of crystallinity in RB, 60.5%, also indicates the enhancement of the catalytic performance of the material significantly more favorable to improve the adsorption efficiency of transitional compounds. In contrast, an increase of the atomic O/C ratio in RB, 0.51 delineated high breakdown of the cellulosic component, which is favorable for biofuel purpose. 13.98% SiO2 reduction in RB confirmed ash content minimization and better quality of fuel properties. Therefore, the rice husk biochar through HTC can be considered a suitable material for further application to treat wastewater and generate bioenergy.

scholarly journals Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xi Zhang ◽  
Guoqing Cui ◽  
Haisong Feng ◽  
Lifang Chen ◽  
Hui Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Value Added ◽  
Catalytic Performance ◽  
Single Atom ◽  
Glycerol Hydrogenolysis ◽  
Single Atom Alloy

AbstractSelective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems.

scholarly journals Copper nanoparticle ensembles for selective electroreduction of CO2 to C2–C3 products

2017 ◽  
Vol 114 (40) ◽  
pp. 10560-10565 ◽  
Author(s):  
Dohyung Kim ◽  
Christopher S. Kley ◽  
Yifan Li ◽  
Peidong Yang
Keyword(s):  
Aqueous Media ◽  
Direct Conversion ◽  
Catalytic Performance ◽  
Product Formation ◽  
Stable Operation ◽  
Grand Challenge ◽  
Hydrogen Electrode ◽  
Faradaic Efficiency ◽  
Onset Potential ◽  
Rate Determining Step

Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2 reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective formation of C2–C3 products at low overpotentials. Densely packed Cu NP ensembles underwent structural transformation during electrolysis into electrocatalytically active cube-like particles intermixed with smaller nanoparticles. Ethylene, ethanol, and n-propanol are the major C2–C3 products with onset potential at −0.53 V (vs. reversible hydrogen electrode, RHE) and C2–C3 faradaic efficiency (FE) reaching 50% at only −0.75 V. Thus, the catalyst exhibits selective generation of C2–C3 hydrocarbons and oxygenates at considerably lowered overpotentials in neutral pH aqueous media. In addition, this approach suggests new opportunities in realizing multicarbon product formation from CO2, where the majority of efforts has been to use oxidized copper-based materials. Robust catalytic performance is demonstrated by 10 h of stable operation with C2–C3 current density 10 mA/cm2 (at −0.75 V), rendering it attractive for solar-to-fuel applications. Tafel analysis suggests reductive CO coupling as a rate determining step for C2 products, while n-propanol (C3) production seems to have a discrete pathway.

Cu/CuxOy NPs architectured COF: a recyclable catalyst for the synthesis of oxazolidinedione via atmospheric cyclizative CO2 utilization

2020 ◽  
Vol 56 (81) ◽  
pp. 12202-12205
Author(s):  
Somnath Sarkar ◽  
Swarbhanu Ghosh ◽  
Jahangir Mondal ◽  
Sk. Manirul Islam
Keyword(s):  
Catalytic System ◽  
Value Added ◽  
Recyclable Catalyst ◽  
Co2 Utilization ◽  
Heterogeneous Catalytic ◽  
Heterogeneous Catalytic System

This work emphasizes the utility of COFs in establishing a heterogeneous catalytic system for the generation of value-added oxazolidinediones under alkali-free conditions (sustainable approach).

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