A versatile electrochemical cell for in-situ GI-XRD measurements on lab-scale XRD devices

In-situ X-ray diffraction (XRD) cells for electrochemical experiments suffer from strong attenuation of primary and diffracted beams within the electrolyte solution. To reduce the intensity loss of the X-rays, the use of a thin layer of electrolyte solution is an essential element of the conventional cell design. On the other hand, the thin layer electrolyte geometry is a considerable limitation for electrochemical measurements. To overcome these drawbacks a versatile electrochemical cell for in-situ GI-XRD measurements was constructed and used for the electrodeposition of Cu2O thin films on a copper substrate. In this design, a thin copper metal film working electrode is applied on a polyimide foil and then backside-illuminated in GI-XRD geometry. In this way, the XRD pattern is measured from the electrolyte/electrode interface of the working electrode. The X-rays only have to penetrate the polymer foil and the sputtered metal layer, resulting in high-intensity signals. In this work, we demonstrate the abilities of the in-situ cell with quantitative measurements of cathodic deposition of Cu2O thin layers. The results show a good agreement between the diffracted X-ray peak intensities and the calculated and measured thicknesses of the oxide layers. The cell design allows the structural characterization of electrode surfaces during electrochemical measurements without the disadvantages of thin layer cells and therefore does not require high intensity synchrotron radiation to perform X-ray diffraction during electrochemical investigations.