Copper catalysts for electrochemical CO
An electrochemical method includes performing anodic halogenation of Cu foils, performing subsequent oxide-formation in a KHCO 3 electrolyte, and performing an electroreduction in neutral KHCO 3 to generate a copper catalyst.
1. An electrochemical method comprising:
performing anodic halogenation of Cu foils; wherein the anodic halogenation comprises 60-100 s at 1.1 V (vs. Ag/AgCl) for KCI, 60-90 s at 0.18 V (vs. Ag/AgCl) for KBr, or 1-10 s at −0.2 V (vs. Ag/AgCl) for KI;
performing subsequent oxide-formation in a KHCO 3 electrolyte; and
performing an electroreduction in neutral KHCO 3 to generate a copper catalyst comprising cubic structures of Cu and a surface roughness of less than 30; the catalyst capable to provide a faradaic efficiency ≥50% for C 2 H 4 generation.
2. The electrochemical method of claim 1 wherein the electroreduction in neutral KHCO 3 is by linear sweep voltammetry (LSV).
3. The electrochemical method of claim 1 wherein performing anodic halogenation of Cu foils comprises applying an oxidative potential to electropolished Cu foils immersed in an electrolyte containing halide ions.
4. The electrochemical method of claim 1 , further comprising:
prior to performing the anodic halogenation of the Cu foils;
mechanically polishing the Cu foils;
rinsing the polished the Cu foils;
electropolishing the Cu foils by chronoamperometry in 85% phosphoric acid at 1.5 V with a Cu counter electrode in a two-electrode configuration;
rinsing the electropolished Cu foils;
cutting the electropolished Cu foils into 2×0.5 cm 2 pieces;
flattening the electropolished Cu foils;
covering a back side and part of a front side of the flattened electropolished Cu foils with polyimide (PI) tape to define a geometric area of a working electrode; and
wrapping the working electrode in PTFE tape to prevent detachment of the PI tape, exposing an area of 0.35 cm 2 .
5. The electrochemical method of claim 4 , further comprising:
dissolving KCl, KBr, and KI in de-ionized (DI) water to a concentration of 0.1 M; and
performing the anodic halogenation on an electropolished Cu foil immersed in 0.1 M KCl, KBr, and KI, respectively, in a three-electrode configuration using a potentiostat.
6. The electrochemical method of claim 5 wherein a counter electrode is Pt gauze.
7. The electrochemical method of claim 6 wherein a reference electrode was Ag/AgCl (saturated KCl) electrode.
8. The electrochemical method of claim 7 wherein open circuit potentials of electropolished Cu in 0.1 M KCl, KBr, and KI are −0.115 V, −0.134 V, and −0.315 V vs. Ag/AgCl.