High-Speed in situ Surface X-ray Diffraction Studies of the Electrochemical Dissolution of Au(001)

Abstract

We present in situ X-ray surface diffraction studies of interface processes with data acquisition rates in the millisecond regime, using the electrochemical dissolution of Au(001) in Cl-containing solution as an example. This progress in time resolution permits monitoring of atomic-scale growth and etching processes at solid-liquid interfaces at technologically relevant rates. Au etching was found to proceed via a layer-by-layer mechanism in the entire active dissolution regime up to rates of ∼20 ML/s. Furthermore, we demonstrate that information on the lateral surface morphology and in-plane lattice strain during the electrochemical process can be obtained.

Anomalous Potential Dependence in Homoepitaxial Cu(001) Electrodeposition: AnIn SituSurface X-Ray Diffraction Study

“…A crossover from 3D to layer-by-layer and finally to step-flow growth was observed with increasing potential. Since the deposition rate was identical at all potentials, this behavior has to be caused by an increase in the Au surface mobility with potential, which is in good agreement with STM results on Au coarsening in this environment [12][13][14] and SXRD results on the Au(001) dissolution behavior, which revealed step-flow or layer-by-layer growth up to very high dissolution rates [11]. Here we apply in situ SXRD to studies of Cu(001) growth.…”

“…In contrast to these measurements, atomicscale studies of copper in Cl-containing electrolytes up to now were limited to the double layer potential regime or growth at very low deposition rates [5,6,8,9], where Cu (001) grows exclusively via a step-flow mechanism. How the atomic-scale growth proceeds under conditions resembling those during industrial electroplating is currently unclear.We recently demonstrated for the case of Au homoepitaxial deposition and dissolution that in situ SXRD allows studying very fast electrochemical growth, up to 20 monolayers (ML) per second [10,11], i.e., close to technologically relevant rates. For diffusion-limited Au deposition from a Cl-containing electrolyte on unreconstructed Au (001), these studies revealed a pronounced dependence of the growth behavior on the deposition potential.…”

“…We recently demonstrated for the case of Au homoepitaxial deposition and dissolution that in situ SXRD allows studying very fast electrochemical growth, up to 20 monolayers (ML) per second [10,11], i.e., close to technologically relevant rates. For diffusion-limited Au deposition from a Cl-containing electrolyte on unreconstructed Au (001), these studies revealed a pronounced dependence of the growth behavior on the deposition potential.…”

“…We employed the ''hanging meniscus'' electrochemical cell and 1D x-ray pixel detector as in our previous SXRD studies [10,11]. For each experiment, the Cu(001) single crystal sample (Mateck, 99.999%, miscut <0:05 ) was prepared by electropolishing in 70% orthophosphoric acid [6], rinsed with Milli-Q water, and then mounted in the SXRD cell.…”

Dynamics of the Au (001) surface in electrolytes:In situcoherent x-ray scattering

“…5 The dynamics of electrochemical interfaces have been studied with surface x-ray scattering on timescales down to 10 −3 sec. While this incoherent surface x-ray scattering can achieve high time resolution, we took an approach using coherent x rays to study the electrochemical interfaces in order to examine the slow equilibrium dynamics to which incoherent x rays are not sensitive.…”