Dynamics of lifting the Au(111) reconstruction in perchloric acid electrolyte

The striped p × √3 reconstruction of Au(111) is a textbook example of how electrode surfaces reorganise in response to an applied potential. Using in situ high-energy surface X-ray diffraction, we track the surface reconstruction in 0.1 M HClO₄electrolyte while the potential is cycled at both 5 mV s⁻¹and 2 mV s⁻¹between 0.06 V and 0.86 V versus RHE. Reciprocal-space maps, collected every ∼10 s, show that the unit cell of the well-known herringbone reconstruction increases in length progressively as the potential is swept positively; the diffraction spots coalesce with the spot from the (111) surface and the reconstruction lifts completely above ≈0.7 V. The lifting and reformation dynamics of the surface reconstruction are seen to be relatively slow and continuous, when the potential is swept at 5 mV s⁻¹we observe the reconstruction lifting at more positive potentials than when swept at 2 mV s⁻¹. Conversely the reforming of the reconstruction is also slow and is present at more positive potentials when the sweep rate is slower.