Reversibility of Ferri-Ferrocyanide Redox during in-Situ Soft X-Ray Spectroscopy
We studied the photochemical response of ferri-ferrocyanide to intense synchrotron radiation by in-situ X-ray absorption spectroscopy at the iron L edge. For photon flux densities above a defined threshold, precipitation of ferric (hydr)oxide from both ferricyanide and ferrocyanide solutions was clearly detectable. The formation of the precipitate was accelerated during cyclic voltammetry, which we probed by time-resolved in-operando X-ray absorption spectroscopy. The iron redox was completely inhibited in the probed volume after only two electrochemical cycles (70 min). Our study highlights the importance of considering both electrochemical and spectroscopic conditions when designing in-situ experiments that can shed light on charge transfer and chemistry of active sites in energy and health research.