The structural transformation of the Pt(1 1 0) electrode during the Cu underpotential deposition process

The underpotential deposition (UPD) of copper on the Pt(1 1 0) electrode in 0.5 M H2SO4 was studied by in situ scanning tunneling microscopy and IRAS. It was revealed that UPD copper produces the (1×1) structure as long as the sample potential is kept below 670 mV (vs. standard hydrogen electrode, SHE). After potential cycles over 60 min at the range of 220–1070 mV (vs. SHE), the surface is irreversibly transformed into the (1×n) reconstructed structure. The UPD copper traces the substrate (1×n). The irregular band shift of the SO4 stretching mode observed by IRAS is also discussed.