Authors: SI Lee S Mitani SH Yoon KH Choi Y Korai K Saito I Mochida
Publish Date: 2005/11/18
Volume: 82, Issue: 4, Pages: 647-652
Abstract
H2SO4 adsorption was studied by solidstate 2HNMRand temperatureprogrammed desorption TPD on a series of pitchbased activated carbon fibers ACFs and compared to their electric doublelayer capacitance in H2SO4 and Et4NBF4 Three states of H2SO4 were found by magic angle spinning MAS2HNMR namely species adsorbed on the walls trapped in the pores and staying over the outer surface of the ACFs respectively Protons of H2SO4 are strongly fixed on the walls of small pores whereas in the larger pores they are rather mobile due to exchange The adsorbed protons on the pore walls contribute to the capacitance while their exchange with the protons of H2SO4 in the pores appears to decrease their contribution to the capacitance The capacitance of ACFs with smaller surface area is correlated to the amount of SO2 desorbed by TPD up to 200 °C By contrast for other ACFs of larger surface area the amount up to the same temperature was found to be much larger than their capacitance The contribution of H2SO4 adsorbed in the latter ACFs is much less effective for their capacitance
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