XPS analysis of activated carbon supported ionic liquids: Enhanced purity and reduced charging

Herein we report on XPS measurements on five different [EMIM] based ionic liquids (IL) prepared on activated carbon and aluminium supports. The anions were [TFSI] [BF4], [FAP], [B(CN)(4)] and [EtOSO3]. The results show that impurities such as O, Si or hydrocarbons were significantly reduced or no longer detected when preparation was performed on the high surface area carbon support. All core level spectra were fitted and for [EMIM][FAP], [EMIM][B(CN)(4)] and [EMIM][EtOSO3] de-convolution procedures of the C 1s lines are suggested. Comparison of the determined binding energies with published data strongly suggests that sample charging is irrelevant when preparation is performed on the activated carbon support. This observation is supposed to refer to the high capacitance of the high surface area carbon. (C) 2011 Elsevier B.V. All rights reserved.