Structure-Sensitive CO 2 Electroreduction to Hydrocarbons on Ultrathin 5-fold Twinned Copper Nanowires

Liu

et al. 2017

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Climate change, caused by heavy CO emissions, is driving new demands to alleviate the rising concentration of atmospheric CO levels. Enlightened by the photosynthesis of green plants, photo(electro)chemical catalysis of CO reduction, also known as artificial photosynthesis, is emerged as a promising candidate to address these demands and is widely investigated during the past decade. Among various artificial photosynthetic systems, solar-driven electrochemical CO reduction is widely recognized to possess high efficiencies and potentials for practical application. The efficient and selective electroreduction of CO is the key to the overall solar-to-chemical efficiency of artificial photosynthesis. Recent studies show that various metallic materials possess the capability to play as electrocatalysts for CO reduction. In order to achieve high selectivity for CO reduction products, various efforts are made including studies on electrolytes, crystal facets, oxide-derived catalysts, electronic and geometric structures, nanostructures, and mesoscale phenomena. In this Review, these methods for tuning the selectivity of CO electrochemical reduction of metallic catalysts are summarized. The challenges and perspectives in this field are also discussed.

Section: Design Of Electrocatalystsmentioning

confidence: 99%

Tuning of CO₂ Reduction Selectivity on Metal Electrocatalysts

Liu

et al. 2017

Small

196

125

“…Copper‐based materials represent the only category of electrocatalysts reported to date that can reduce CO 2 to hydrocarbons and alcohols with good selectivity and efficiency . As a nonprecious metal with the capability of producing deep reduction products, copper and its derivatives, including alloys, compounds, and composites, are considered to have strong potential for comprehensive utilization of CO 2 through direct conversion into different value‐added reduction products.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Copper‐Based Electrocatalysts for CO₂ Reduction

et al. 2018

The continuous increase of CO2 concentration in the atmosphere has been imposing an imminent threat for global climate change and environmental hazards. In recent years, the electrochemical or photochemical conversion of CO2 into value‐added chemicals or fuels has received significant attention, as it may enable an attractive means to mitigate the atmospheric CO2 concentration and complete the imbalanced carbon‐neutral energy cycle, as well as create renewable energy resources for human use. Among the different electrocatalysts being studied, Cu‐based materials have been demonstrated as the only category of candidates that allows the conversion of CO2 into a variety of reducing products, including carbon monoxide, hydrocarbons, and alcohols. Herein, the reaction pathways for different Cu‐based catalysts for C1 and C2+ products are introduced. Then, different parameters in tuning Cu‐based electrocatalysts are summarized and discussed, including the morphologies, compositions, crystal facets, and oxide derivation. In addition, various types of parameters for CO2 electroreduction are also described, particularly the option of electrolytes such as aqueous, ionic liquids, and organic solutions. Finally, the current challenges are discussed and the potential strategies to facilitate the future development of CO2 electroreduction are summarized.

“…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 electrodeposition from solution 6,17,25,26 .…”

mentioning

confidence: 99%

“…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 electrodeposition from solution 6,17,25,26 .…”

mentioning

confidence: 99%

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

et al. 2018

Self Cite

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 ...