Selective Electroreduction of CO<sub>2</sub> toward Ethylene on Nano Dendritic Copper Catalysts at High Current Density

Reller, Christian; Krause, Ralf; Волкова, Е. Г.; Schmid, Bernhard; Neubauer, Sebastian; Rucki, A.; Schuster, Manfred Erwin; Schmid, Günter

doi:10.1002/aenm.201602114

Cited by 233 publications

(219 citation statements)

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“…The screening was conducted on freshly prepared in situ-grown model catalyst on a solid copper support as also described in the previous work [54]. This method is more feasible for liquid or solid model reagents and allowed more precise measurements due to the reduced electrolyte volumes.…”

Section: Model Reagent Screeningmentioning

confidence: 99%

“…Thusly, we chose to directly compare CO 2 (1) and CO (2) under identical high current density conditions (Figure 2). Like in the original publication [54], these experiments were conducted with gas diffusion electrodes at 170 mAcm −2 .…”

Section: Co Bulk Electrolysis At High Current Densitymentioning

confidence: 99%

“…We recently introduced a nano-scale copper dendrite electro-catalyst, which on a carbon gas diffusion layer (GDL) is capable of achieving over 50% Faradaic Efficiency (FE) for ethene at 170 mAcm −2 [53,54]. For this screening, this was the model catalyst of choice.…”

Section: Co 2 Bulk Electrolysis Benchmarkmentioning

confidence: 99%

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Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

et al. 2017

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Abstract:The direct electro-reduction of CO 2 to functional molecules like ethene is a highly desirable variant of CO 2 utilization. The formation of, for example, ethene from CO 2 is a multistep electrochemical process going through various intermediates. As these intermediates are organic species, the CO 2 reducing electro-catalyst has to be competent for a variety of organic functional group transformations to yield the final product. In this work, the activity of an in situ-grown nano-structured copper catalyst towards a variety of organic functional group conversions was studied. The model reagents were selected from the product spectrum of actual CO 2 reduction reaction (CO 2 RR) experiments and from proposals in the literature. The CO 2 bulk electrolysis benchmark was conducted at 170 mAcm −2 current density with up to 43% Faradaic Efficiency (FE) for ethene and 23% FE for ethanol simultaneously. To assure relevance for application-oriented conditions, the reactivity screening was conducted at elevated current densities and, thus, overpotentials. The found reactivity pattern was then also transferred to the CO reduction reaction (CORR) under benchmark conditions yielding additional insights. The results suggest that at high current density/high overpotential conditions, also other ethene formation pathways apart from acetaldehyde reduction such as CH 2 dimerization are present. A new suggestion for a high current density mechanism will be presented, which is in agreement with the experimental observations and the found activity pattern of copper cathodes toward organic functional group conversion.

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Section: Model Reagent Screeningmentioning

confidence: 99%

Section: Co Bulk Electrolysis At High Current Densitymentioning

confidence: 99%

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Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

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“…Copper catalysts with different morphologies have been synthesized through annealing, chemical treatments on thin films, colloidal synthesis and electrodeposition from solution 6,17,25,26 . For example, recent work reported selective ethylene production on bromide-promoted copper dendrites with a maximum ethylene FE of 57% (ref.…”

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confidence: 99%

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

et al. 2018

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As energy demand continues to increase, so too do anthropogenic carbon emissions and global temperatures. Renewable energy sources such as solar, wind and hydroelectricity displace fossil fuel carbon emissions and continue to progress to wider deployment. However, long-term (seasonal) energy storage remains a challenge that must be addressed for renewables to meet a major fraction of global energy demand 1 . Carbon dioxide electroreduction to renewable fuels and feedstocks provides an energy storage solution to the seasonal variability of renewable energy sources 2 . When coupled with carbon capture technology, the carbon dioxide reduction reaction (CO 2 RR) offers a means to close the carbon cycle.CO 2 RR electrocatalysts lower energetic barriers to CO 2 reduction by stabilizing intermediates and transition states in the multistep electrochemical reduction process 3 . Copper reduces CO 2 to a wide range of hydrocarbon products such as methane, ethylene, ethanol and propanol 4 . Unfortunately, bulk copper is not selective among various carbon products, and it also suffers Faradaic efficiency (FE) losses to the competing hydrogen evolution reaction.Among possible products, C2+ hydrocarbons are highly sought in view of their commercial value. Ethylene, for example, is a precursor to the production of polyethylene, a major plastic. Selectively producing ethylene over methane circumvents costly paraffin-olefin separation 5 . Developing catalysts that work at ambient conditions to produce C2 selectively over C1 gaseous products will increase the relevance of renewable feedstocks in the chemical sector.Oxide-derived copper is one class of catalyst that has shown enhanced CO 2 RR activity and increased selectivity towards multi-carbon products [6][7][8] . The selectivity of these catalysts is dependent on structural morphology and copper oxidation state 9-17 . Electrochemical reduction of copper oxide catalyst films can lead to grain boundaries, undercoordinated sites and roughened surfaces that are hypothesized to be catalytically active sites 8,18 . Residual oxides, proposed to play a key role in catalysis, may exist after electrochemical reduction 7 . A recent report of oxygen plasma-activated oxide-derived copper catalysts achieved an ethylene FE of 60% at − 0.9 V versus reversible hydrogen electrode (RHE) 9 , with activity attributed to the presence of Cu + species. In situ hard X-ray absorption spectroscopy (hXAS) experiments have suggested stable Cu + species exist at highly negative CO 2 RR potentials of ~− 1.0 versus RHE 9 . However, the presence of Cu + species during CO 2 RR is still the subject of debate; 7,19 and in situ tracking of the copper oxidation state with time resolution during CO 2 RR has remained elusive.Morphological effects of copper nanostructures have a significant effect on the selectivity of CO 2 RR to multi-carbon products [20][21][22][23][24] . Copper catalysts with different morphologies have been synthesized through annealing, chemical treatments on thin films, colloidal synthesis and ...

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“…The impact would be larger if the CO 2 is not converted into fuels but in high-value products, which may make sense in certain cases (e.g., ethylene) 17 …”

Section: Scalementioning

confidence: 99%

Perspectives on the photoelectrochemical storage of solar energy

Krol

Parkinson

2017

MRS Energy & Sustainability

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Direct photoelectrochemical water splitting offers several advantages over PV-powered electrolysis and may become the technology of choice in the future. However, significant R&D efforts and breakthroughs are needed to accomplish this goal.The sustainable production of hydrogen would be an important first step for both powering fuel cells and for enabling large-scale and technologically mature gas phase processes to reduce CO 2 and nitrogen to get desired products. Specifically, the central challenge is to produce hydrogen from water using sunlight. Photovoltaics and wind-powered electrolysis are likely to be the technology of choice to produce renewable hydrogen for the next few decades. However, the integration of light absorption and catalysis in 'direct' photoelectrolysis routes offers several advantages, such as lower current densities and better heat management, and may become technologically relevant in the second half of this century. This article discusses the research and development efforts and needed breakthroughs to achieve this goal. New chemically stable semiconductors with a band gap between 1.5 and 2.0 eV and long carrier lifetimes are urgently needed to make efficient tandem devices.Scale-up of these research level devices beyond a few cm 2 introduces mass transport limitations that require creative electrochemical engineering solutions. Last but not least, standardized methods for measuring efficiencies and stabilities need to be implemented and should lead to official benchmarking and certification laboratories to guide commercial scale up efforts. Keywords: photochemical; energy storage; energy generation RevIew DISCUSSION POINTS• Water splitting will be a central challenge for any future fossil fuel-free energy infrastructure that relies on liquid or gaseous chemical fuels.• While the main materials challenge for solar-and wind-driven electrolysis is the development of better catalysts, the main challenge for photoelectrochemical water splitting is to find new chemically stable optimal-bandgap semiconducting light absorbers.• Further progress in the development of photo-driven water splitting generators requires significant additional efforts in electrochemical engineering and the development of standardized methods for benchmarking device performance and stability.

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Selective Electroreduction of CO₂ toward Ethylene on Nano Dendritic Copper Catalysts at High Current Density

Cited by 233 publications

References 29 publications

Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

Perspectives on the photoelectrochemical storage of solar energy

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Selective Electroreduction of CO2 toward Ethylene on Nano Dendritic Copper Catalysts at High Current Density

Cited by 233 publications

References 29 publications

Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

Reactivity of Copper Electrodes towards Functional Groups and Small Molecules in the Context of CO2 Electro-Reductions

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

Perspectives on the photoelectrochemical storage of solar energy

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Selective Electroreduction of CO₂ toward Ethylene on Nano Dendritic Copper Catalysts at High Current Density