In Situ Spectroscopic Study of CO₂ Electroreduction at Copper Electrodes in Acetonitrile

Abstract

The electrochemical conversion of carbon dioxide (CO 2 ) into valuable compounds is a promising route toward the valorization of this molecule of high environmental impact. Yet, an industrial process involving CO 2 electroreduction is still far from reality and requires deep and fundamental studies for a further understanding and better development of the process. In this work, we describe in situ spectroelectrochemical studies based on Fourier transform infrared spectroscopy and surface-enhanced Raman spectroscopy of the CO 2 reduction in acetonitrile solutions at copper electrodes. The influence of factors such as the water content and the supporting electrolyte on the reaction products were evaluated and compared to products obtained on metal electrodes other than Cu, such as Pt, Pb, Au, Pd, and Ag. The results show that at Cu electrodes in acetonitrile containing small amounts of water, the main reaction products from CO 2 reduction are carbonate, bicarbonate, and CO. The formation of CO was observed at less-negative potentials than the formation of (bi)carbonates, and the formation of carbonate and bicarbonate species appears to be the result of a reaction with electrochemically generated OH − from water reduction. In general, our experiments show the sensitivity of the CO 2 reduction reaction to the presence of water, even at the residual level.

Enhancing CO2 electrolysis through synergistic control of non-stoichiometry and doping to tune cathode surface structures

“…In contrast, all samples with adsorbed CO 2 show absorption signals in two distinct infrared bands at room temperature in Supplementary Fig. 9c,d, that is, 2,380–2,300 cm −1 , which is associated with CO 2 molecules25 on the sample surface, and 1,500–1,430 cm −1 , which is typically observed for CO 3 2− (ref. 26).…”

Mechanistic Study of the Electrosynthesis of Propylene Carbonate from Propylene Oxide and CO2 on Copper Electrodes

“…We note that the reported gas-phase and liquid-phase spectra of PO show bands in the 1000-1500 cm À 1 range, [18] but these bands are too weak (see the black spectrum in this wavenumber range in Figure 2) to be used for identification under the conditions of our experiment, The absorbance spectrum of propylene carbonate in Figure 2 shows that PC is best identified by the characteristic C=O stretching band at 1800 cm À 1 . These latter bands can be attributed to (bi)carbonate species, CO 3 2À , HCO 2 À , CO 3 2À and CO 3 2À respectively, as described by Figueiredo et al [17] Previous studies suggested that the existence of different vibrational bands for C=O and CÀ O bonds on bicarbonates and carbonates is due to the presence of different ion pairs of the anions with TEA + cations or solvation shells with residual water. The assignment of the different bands was done with the help of the transmission spectra and previous reports on CO 2 electrochemical reduction in acetonitrile [17] and is summarized in table 2.…”

“…Therefore, we have collected in Table 1 the corresponding electrode potentials. The assignment of the different bands was done with the help of the transmission spectra and previous reports on CO 2 electrochemical reduction in acetonitrile [17] and is summarized in table 2. The results show that PO in the acetonitrile electrolyte does not present strong IR modes that can be used for its identification, while PC clearly shows features that aid in its identification with vibrational bands at 1800, 1392, 1184, 1118 and 1053 cm À 1 .…”

Highly efficient electrochemical reforming of CH 4 /CO 2 in a solid oxide electrolyser

“…The exsolved interfaces are expected to have enhanced catalytic activity, whereas the LSCM with oxygen nonstoichiometry may facilitate chemical CO 2 adsorption/activation at high temperatures. Figure 3A shows the chemical adsorption of CO 2 at 800°C in the in situ Fourier transform infrared (FTIR) test, which demonstrates the effective chemical adsorption/activation of CO 2 as confirmed by the transition state (TS) between the CO 2 molecule and the carbonate ion ( 19 , 20 ). With the exsolved interfaces, significant enhancement of chemical adsorption/activation of CO 2 would be anticipated on the tailored LSCM scaffold.…”