Dataset Information

PH effects on the electrochemical reduction of CO₍₂₎ towards C₂ products on stepped copper.

ABSTRACT: We present a microkinetic model for CO₍₂₎ reduction (CO₍₂₎R) on Cu(211) towards C₂ products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C₁ vs C₂ activity arise from differences in their multi-step mechanisms. We find the depletion in C₂ products observed at high overpotential and high pH to arise from the 2^nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C₁ pathway. We further demonstrate that CO₍₂₎ reduction at a fixed pH yield similar activities, due to the facile kinetics for CO₂ reduction to CO on Cu, which suggests C₂ products to be favored for CO₂R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C₂ products.

SUBMITTER: Liu X

PROVIDER: S-EPMC6318338 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

pH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper.

Liu Xinyan X Schlexer Philomena P Xiao Jianping J Ji Yongfei Y Wang Lei L Wang Lei L Sandberg Robert B RB Tang Michael M Brown Kristopher S KS Peng Hongjie H Ringe Stefan S Hahn Christopher C Jaramillo Thomas F TF Nørskov Jens K JK Chan Karen K

Nature communications 20190103 1

We present a microkinetic model for CO(2) reduction (CO(2)R) on Cu(211) towards C2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C1 vs C2 activity arise from differences in their multi-step mechanisms. We find the depletion in C2 products observed at high overpotential and high pH to arise from the 2nd order dependence of C ...[more]

PMID: 30604776

Similar Datasets

Project description:The electrochemical reduction of CO2 is widely studied as a sustainable alternative for the production of fuels and chemicals. The electrolyte's bulk pH and composition play an important role in the reaction activity and selectivity and can affect the extent of the buildup of pH gradients between the electrode surface and the bulk of the electrolyte. Quantifying the local pH and how it is affected by the solution species is desirable to gain a better understanding of the CO2 reduction reaction. Local pH measurements can be realized using Scanning Electrochemical Microscopy (SECM); however, finding a pH probe that is stable and selective under CO2 reduction reaction conditions is challenging. Here, we have used our recently developed voltammetric pH sensor to perform pH measurements in the diffusion layer during CO2 reduction using SECM, with high time resolution. Using a 4-hydroxylaminothiophenol (4-HATP)/4-nitrosothiophenol (4-NSTP) functionalized gold ultramicroelectrode, we compare the local pH developed above a gold substrate in an argon atmosphere, when only hydrogen evolution is taking place, to the pH developed in a CO2 atmosphere. The pH is monitored at a fixed distance from the surface, and the sample potential is varied in time. In argon, we observe a gradual increase of pH, while a plateau region is present in CO2 atmosphere due to the formation of HCO3 - buffering the reaction interface. By analyzing the diffusion layer dynamics once the sample reaction is turned "off", we gain insightful information on the time scale of the homogeneous reactions happening in solution and on the time required for the diffusion layer to fully recover to the initial bulk concentration of species. In order to account for the effect of the presence of the SECM tip on the measured pH, we performed finite element method simulations of the fluid and reaction dynamics. The results show the significant localized diffusion hindrance caused by the tip, so that in its absence, the pH values are more acidic than when the tip is present. Nonetheless, through the simulation, we can account for this effect and estimate the real local pH values across the diffusion layer.

Dataset Information

PH effects on the electrochemical reduction of CO₍₂₎ towards C₂ products on stepped copper.

Publications

pH effects on the electrochemical reduction of CO<sub>(2)</sub> towards C<sub>2</sub> products on stepped copper.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

PH effects on the electrochemical reduction of CO(2) towards C2 products on stepped copper.

Publications

pH effects on the electrochemical reduction of CO<sub>(2)</sub> towards C<sub>2</sub> products on stepped copper.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

PH effects on the electrochemical reduction of CO₍₂₎ towards C₂ products on stepped copper.