Surface reconstruction of pure-Cu single-crystal electrodes under CO-reduction potentials in alkaline solutions: A study by seriatim ECSTM-DEMS

摘要: Quasi-operando electrochemical scanning tunneling microscopy (ECSTM) recently showed that a polycrystalline Cu electrode kept in 0.1 M KOH at − 0.9 V (SHE), potential very close to for CO reduction, underwent two-step surface reconstruction, initially Cu(111), or Cu(pc)-[Cu(111)], and terminally Cu(100), Cu(pc)-[Cu(100)]. When subjected monolayer-limited Cu_((s)) ↔ Cu_2O_((s)) oxidation-reduction cycles (ORC), the Cu(pc)-[Cu(100)] was further transformed Cu(pc)-[Cu(511)] produced C_2H_5OH exclusively, as detected by differential mass spectrometry, an overvoltage lower 645 mV relative formation of hydrocarbons. In this paper, results are presented from studies with native monocrystalline surfaces Cu(100) Cu(110). Whereas intermediate Cu(pc)-[Cu(111)] layer eventually converted Cu(pc)-[Cu(100)], pristine Cu(111) single crystal itself no such conversion. The original likewise proved impervious perturbations. contrast, outer plane Cu(110) three transformations: first disordered Cu(110)-d[Cu(110)], then Cu(110)-d[Cu(111)], finally ordered Cu(110)-[Cu(100)] plane. After multiple ORC, [Cu(100)] lattice atop did not generate ethanol, contrast phase above Cu(pc) bulk. ECSTM captured disparity: Post-ORC, converted, Cu(110)-[Cu(511)], but catalytically inactive Cu(110)-[Cu(111)]; hence, C2H5OH production upon reduction CO, would have been case stepped Cu(511) surface.