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Real‐time Monitoring Reveals Dissolution/Redeposition Mechanism in Copper Nanocatalysts during the Initial Stages of the CO2 Reduction Reaction

“…[32,34,40] As imilar process of anomalous dissolution of Cu under cathodic polarization in acidic media has been studied and its chemical conjugation to oxygen reduction reaction was suggested as an explanation. [41,42] Another possibility is the migration of negatively charged transient Cu À species in awater depletion layer close to the electrode surface;aprocess referred to as cathodic corrosion. [43] This process was observed on Pt electrodes at potentials as high as À0.5 Vvs.…”

Cathodic Corrosion of Cu Substrates as a Route to Nanostructured Cu/M (M=Ag, Au, Pd) Surfaces

“…However, for corrosion to occur Cu must still be oxidised, which is facilitated by the presence of trace oxygen. Therefore, previous investigations [5,11] have proposed that Cu x O x/2(ads) -type oxides are formed on the surface, which can dissolve in acidic media to generate Cu electrolyte was checked pre-and post-electrodeposition by AAS, and no evidence of copper was found in the solution, indicating that the process was confined to Cu (aq) ions that may have been formed were reduced at the surface. The latter is not too surprising in the context of the work of Kreizer and co-workers, as metals electrodeposited using the approach reported here are very rough (Figure 1) and, therefore, contain numerous nucleation sites where Cu deposition would occur.…”

“…However, for corrosion to occur Cu must still be oxidised, which is facilitated by the presence of trace oxygen. Therefore, previous investigations [5,11] have proposed that Cu x O x/2(ads) -type oxides are formed on the surface, which can dissolve in acidic media to generate Cu + (ads) that can be oxidised to Cu 2 + (ads) in the presence of O 2 . Under cathodic polarisation conditions, this oxidised Cu can be reduced to the metallic form (Cu (s) ) or diffuse to the bulk as Cu 2 + (aq) if there is a very low concentration of crystallisation sites.…”

“…It must be noted that in those reports the evolution of hydrogen was not involved. However, according to the studies of Kreizer and coworkers, [5,11] Cu can be electrochemically dissolved under cathodic polarisation conditions, which is promoted when the electrode/electrolyte layer is perturbed by hydrogen evolution. However, for corrosion to occur Cu must still be oxidised, which is facilitated by the presence of trace oxygen.…”

“…[4] Kreizer and co-workers reported that copper dissolution occurs under even milder cathodic polarisation conditions [À0.40 to À0.70 V vs. the standard hydrogen electrode (SHE)] in acidic solution in the presence of trace oxygen, which is promoted by the stirring of the electrode/interface layer by bubbles of evolving hydrogen. [5] In that instance, two competing processes are witnessed; namely, the evolution of hydrogen gas together with the re-deposition of dissolved Cu. [5a] Therefore, in this work, the electrodeposition of metals such as Ag, Au and Pd onto Cu are investigated under cathodic polarisation conditions, where hydrogen-gas evolution occurs.…”