CO<sub>2</sub> Reduction Promoted by Imidazole Supported on a Phosphonium-Type Ionic-Liquid-Modified Au Electrode at a Low Overpotential

Published on 2018-02-13T05:32:20Z (GMT) by
The catalytic conversion of CO<sub>2</sub> to useful compounds is of great importance from the viewpoint of global warming and development of alternatives to fossil fuels. Electrochemical reduction of CO<sub>2</sub> using aromatic <i>N</i>-heterocylic molecules is a promising research area. We describe a high performance electrochemical system for reducing CO<sub>2</sub> to formate, methanol, and CO using imidazole incorporated into a phosphonium-type ionic liquid-modified Au electrode, <b>imidazole@IL/Au</b>, at a low onset-potential of −0.32 V versus Ag/AgCl. This represents a significant improvement relative to the onset-potential obtained using a conventional Au electrode (−0.56 V). In the reduction carried out at −0.4 V, formate is mainly generated and methanol and CO are also generated with high efficiency at −0.6 ∼ −0.8 V. The generation of methanol is confirmed by experiments using <sup>13</sup>CO<sub>2</sub> to generate <sup>13</sup>CH<sub>3</sub>OH. To understand the reaction behavior of CO<sub>2</sub> reduction, we characterized the reactions by conducting potential- and time-dependent in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements in D<sub>2</sub>O. During electrochemical CO<sub>2</sub> reduction at −0.8 V, the C–O stretching band for CDOD (or COD) increases and the CO stretching band for COOD increases at −0.4 V. These findings indicate that CO<sub>2</sub> reduction intermediates, CDOD (or COD) and COOD, are formed, depending on the reduction potential, to convert CO<sub>2</sub> to methanol and formate, respectively.

Cite this collection

Iijima, Go; Kitagawa, Tatsuya; Katayama, Akira; Inomata, Tomohiko; Yamaguchi, Hitoshi; Suzuki, Kazunori; Hirata, Kazuki; Hijikata, Yoshimasa; Ito, Miho; Masuda, Hideki (2018): CO2 Reduction Promoted by Imidazole Supported

on a Phosphonium-Type Ionic-Liquid-Modified Au Electrode at a Low

Overpotential. ACS Publications. Collection.