Core Level Data of Ionic Liquids: Monitoring Charging by In Situ Electrochemical X-ray Photoelectron Spectroscopy

The core level binding energies of ionic liquid electrolytes were measured in an ultra high vacuum compatible electrochemical cell by in situ electrochemical XPS. The shifts of the core level spectra are correlated to X-ray induced shifts of the open circuit potential (OCP) of the working electrode (WE). For a low surface area platinum WE, X-ray induced charging of the electrolyte leads to a respective shift of binding energies (BE) of the XP spectra. The OCP of a high surface area activated carbon WE remains almost constant and no significant shift of BE is observed in the XP lines, respectively. (C) 2013 The Electrochemical Society. All rights reserved.