pH and Anion Effects on Cu-Phosphate Interfaces for CO Electroreduction

Pascual, Paula Sebastián; Petersen, Amanda Schramm; Bagger, Alexander; Escudero‐Escribano, María

doi:10.26434/chemrxiv.12745193

Cited by 6 publications

(10 citation statements)

References 43 publications

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“…Transiently stable Cu-oxide species, which have been suggested to be responsible for a transient CO 2 reduction activity can be ruled out as the cause for our transient activity as the anodic pulse potential (0 V vs RHE) is not high enough to oxidize Cu. 15,24 The resting potential of 0 V vs RHE additionally makes sure that the desorption of surface-bound hydrogen at anodic potentials will not occur, which is supported by our previous research in which a potential of approx. 0.2 V vs RHE is necessary to desorb hydrogen.…”

Section: ■ Transient Co Reduction Activity Does Notsupporting

confidence: 57%

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Hochfilzer

Sørensen

et al. 2022

ACS Catal.

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Pulsed electrolysis has shown promise to improve CO(2) reduction activity and steer selectivity by potential pulsing. Nevertheless, a detailed mechanistic understanding of the transient activity upon potential pulsing is still lacking. Utilizing electrochemical mass spectrometry, we demonstrate highly active but short-lived methane and hydrogen transients for pulsed electrochemical CO reduction in phosphate buffer. Compared with the absence of transients in borate buffer, we conclude that methane and hydrogen transients arise from an initial presence and local depletion of phosphate ions, acting as facile proton donors. We further support our conclusion by mass transport modeling, including homogeneous buffering reactions. Our result stresses the importance of the proton donor nature and its local concentration for proton-coupled electron transfer-limited reactions. In this paper, buffer anions improve methane and hydrogen activities transiently by up to one order of magnitude. Similar strategies can be of importance for the selective transformation of more complex biomass molecules and electrosynthesis.

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Section: ■ Transient Co Reduction Activity Does Notsupporting

confidence: 57%

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Hochfilzer

Sørensen

et al. 2022

ACS Catal.

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“…Recent work by Pascual et al . showed that the adsorption strength of phosphate species on different copper facets affects the potential range at which CO poisons the surface, showcasing how the electrode‐electrolyte interface controls the potential range for CO reduction [21] . The second key impact of the electrolyte is on controlling the local pH near the electrode surface.…”

Section: Introductionmentioning

confidence: 99%

Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO₂ Reduction

et al. 2021

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With rising CO2 emissions and growing interests towards CO2 valorization, electrochemical CO2 reduction (eCO2R) has emerged as a promising prospect for carbon recycling and chemical energy storage. Yet, product selectivity and electrocatalyst longevity persist as obstacles to the broad implementation of eCO2R. A possible solution to ameliorate this challenge is to pulse the applied potential. However, it is currently unclear whether and how the trends and lessons obtained from the more conventional constant potential eCO2R translate to pulsed potential eCO2R. In this work, we report that the relationship between electrolyte concentration/composition and product distribution for pulsed potential eCO2R is different from constant potential eCO2R. In the case of constant potential eCO2R, increasing KHCO3 concentration favors the formation of H2 and CH4. In contrast, for pulsed potential eCO2R, H2 formation is suppressed due to the periodic desorption of surface protons, while CH4 is still favored. In the case of KCl, increasing the concentration during constant potential eCO2R does not affect product distribution, mainly producing H2 and CO. However, increasing KCl concentration during pulsed potential eCO2R persistently suppresses H2 formation and greatly favors C2 products, reaching 71 % Faradaic efficiency. Collectively, these results provide new mechanistic insights into the pulsed eCO2R mechanism within the context of proton‐donator ability and ionic conductivity.

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“…165 Moreover, the onset potential of CO adsorption is significantly affected by phosphate anions, which could block the CO adsorption sites because the pK a of adsorbed anions is much lower at EEI than in bulk solution, thus promoting the HER in phosphate-buffered electrolytes. 166 On the other hand, the concentration of buffered anions (e.g., bicarbonate) could have a great impact on the role of bicarbonate in proton-involved RLSs, because higher concentrations of bicarbonate always induce much more H 2 and CH 4 .…”

Section: Anion Effectmentioning

confidence: 99%

Interfacial Electrolyte Effects on Electrocatalytic CO₂ Reduction

et al. 2021

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Electrocatalytic CO2 reduction (CO2RR), powered by renewable energy, has great potential in decreasing the concentration of CO2 in the atmosphere, as well as producing high value-added fuels or chemicals. The electrode and electrolyte together determine the catalytic performance of CO2RR. Despite the substantial progress has been made in the design and preparation of high-performance catalysts, the role of electrolyte at the electrode–electrolyte interface (EEI) which could largely affect the local catalytic environment has not been understood thoroughly. To maximize and balance the catalytic performance (i.e., activity, selectivity, and stability) of CO2RR from a standpoint of application, the fundamental understanding of interfacial electrolyte effects should be emphasized with equal importance to the intrinsic properties of the catalyst. In this Review, we will focus on the discussion of the role (effects) of electrolytes for CO2RR. We summarize the effects of electrolytes according to their compositions and local chemical environment, which include solvents, local pH, cations, anions, impurities, additives, and modifiers. In addition, in-depth investigations on the detection of intermediates during the catalytic reactions using in situ spectroscopy techniques are included. The mechanisms, current challenges, future developments, and perspectives are discussed.

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pH and Anion Effects on Cu-Phosphate Interfaces for CO Electroreduction

Cited by 6 publications

References 43 publications

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO₂ Reduction

Interfacial Electrolyte Effects on Electrocatalytic CO₂ Reduction

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pH and Anion Effects on Cu-Phosphate Interfaces for CO Electroreduction

Cited by 6 publications

References 43 publications

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Transients in Electrochemical CO Reduction Explained by Mass Transport of Buffers

Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO2 Reduction

Interfacial Electrolyte Effects on Electrocatalytic CO2 Reduction

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Product

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Effect of Electrolyte Composition and Concentration on Pulsed Potential Electrochemical CO₂ Reduction

Interfacial Electrolyte Effects on Electrocatalytic CO₂ Reduction