Spectroscopic Observation of a Hydrogenated CO Dimer Intermediate During CO Reduction on Cu(100) Electrodes

Abstract

Carbon dioxide and carbon monoxide can be electrochemically reduced to useful products such as ethylene and ethanol on copper electrocatalysts. The process is yet to be optimized and the exact mechanism and the corresponding reaction intermediates are under debate or unknown. In particular, it has been hypothesized that the C-C bond formation proceeds via CO dimerization and further hydrogenation. Although computational support for this hypothesis exists, direct experimental evidence has been elusive. In this work, we detect a hydrogenated dimer intermediate (OCCOH) using Fourier transform infrared spectroscopy at low overpotentials in LiOH solutions. Density functional theory calculations support our assignment of the observed vibrational bands. The formation of this intermediate is structure sensitive, as it is observed only during CO reduction on Cu(100) and not on Cu(111), in agreement with previous experimental and computational observations.

Promoting Ethylene Selectivity from CO2 Electroreduction on CuO Supported onto CO2 Capture Materials

“…[24,25] Therefore, the high coverage of *COs hould be in favor of the formation of C 2 H 4 . [24,25] Therefore, the high coverage of *COs hould be in favor of the formation of C 2 H 4 .…”

Nature of the Active Sites for CO Reduction on Copper Nanoparticles; Suggestions for Optimizing Performance

“…23 This prediction was supported by recent experiments by Pérez-Gallent et al, who detected a hydrogenated dimer intermediate (*OCCOH) using Fourier transform infrared spectroscopy during CORR at low overpotentials in LiOH solutions. 24 In our recent work, we carried out full solvent QM based metadynamics to determine the RDS for C-C coupling, which we also found associated with the process of first electron transfer. 15,25 Consequently, we take the formation energy of *OCCOH as a descriptor to characterize the performance of surface sites toward C2 production.…”

Structure‐Sensitivity and Electrolyte Effects in CO2 Electroreduction: From Model Studies to Applications

“…Recently, Perez‐Gallent et al. claimed the detection of a protonated dimer (CO‐COH) on Cu(100), using Fourier‐transform infrared spectroscopy (FTIR) (Figure B) . The favourable protonation of the dimer on Cu(100) at potentials prior to the HER has been recently supported by DFT calculations .…”

“…The same experiment carried out on Cu(111) does not show the bands at 1191 cm −1 and 1600 cm −1 reinforcing that a protonated CO dimer is formed on Cu(100) but not on Cu(111). Reprinted with permission from Copyright (2017) WILEY‐VCH VerlagGmbH& Co. KGaA,Weinheim. C) Oxygenate/hydrocarbon ratios for >2e − reduction products as a function of potential for Cu(111), (751), and (100).…”