RESUMO
Using bulk metals as catalysts to get high efficiency in electro-reduction of CO2 is ideal but challenging. Here, we report the coupling of bulk metal electrodes and a ternary ionic-liquid-based electrolyte, 1-butyl-3-methylimidazolium tetrafluoroborate/1-dodecyl-3-methylimidazolium tetrafluoroborate/MeCN to realize highly efficient electro-reduction of CO2 to CO. Over various bulk metal electrodes, the ternary electrolyte not only increases the current density but also suppresses the hydrogen evolution reaction to obtain a high Faradaic efficiency (FE) toward CO. FECO could maintain â¼100% over a wide potential range, and metal electrodes showed very high stability in the ternary electrolyte. It is demonstrated that the aggregation behavior of the ternary electrolyte and the arrangement of two kinds of IL cations with different chain lengths in the electrochemical double layer not only increase the wettability to electrode and CO2 adsorption but also extend the diffusion channel of H+, rendering the high current density and FECO.
RESUMO
Efficient electrode design is crucial for the electrochemical reduction of CO2 to produce valuable chemicals. The solution used for the preparation of electrodes can affect their overall properties, which in turn determine the reaction efficiency. In this work, we report that transition metal salts could induce the change of two-phase ionic liquid/ethanol mixture into miscible one phase. Pre-phase separation region near the phase boundary of the ternary system was observed. Zinc nanoparticles were electro-deposited along the fibres of carbon paper (CP) substrate uniformly in the salt-induced pre-phase separation region solution. The as-prepared Zn(1)/CP electrode exhibits super-wettability to the electrolyte, rendering very high catalytic performance for CO2 electro-reduction, and the Faradaic efficiency towards CO is 97.6% with a current density of 340 mA cm-2, which is the best result to date in an H-type cell.