In situ grazing-incidence X-ray diffraction during electrodeposition of birnessite thin films: Identification of solid precursors

A special electrochemical flow-cell allowing in situ grazing-incidence X-ray diffraction during electrodeposition of thin films has been successfully developed. This original setup is very simple and permits characterisations by reflection onto large surfaces by using an X-ray transparent window used also as a counter electrode. This cell was tested by studying the electrodeposition of birnessite thin films as a function of background electrolytes. In Na2SO4 solution, buserite was identified as the only in situ solid precursor. Its dehydration into birnessite was monitoring in real time and was complete in few minutes. In K2SO4 aerated solution, birnessite was electrodeposited directly as very small crystals. This demonstrates the usefulness of this electrochemical flow-cell for characterising compounds during electrochemical measurements.

Research highlights► Development of a very simple electrochemical cell for in situ XRD characterisation. ► Determination of precursor compounds during electrodeposition of birnessite film. ► Importance of electrolyte background on in situ precursor compound. ► Highlighting of in situ XRD characterisation interests during electrochemistry.