Direct atomic force microscopic determination of surface charge at the gold/electrolyte interface-the inadequacy of classical GCS theory in describing the double-layer charge distribution

摘要

The surface charge at the interface of a Au electrode with a KClO_4 solution was measured by in situ atomic force microscopy(AFM)using a moodified cantilever with a charged SiO_2 sphere.The effective charge determined by treating the AFM force curve was much smaller than that injected electrical double layer.Ion correaltion and ion condensation effects might account for the reduced surface charge.Additional experiemnts on the effect of electrolytes containing divalent species [(Ca(NO_3)_2 and Na_2SO_4] and the effect of adsorption of sodium ddecyl sulfate on the Au electrode provide additional evidence for such effects.