Superviscosity and electroviscous effects at an electrode/aqueous electrolyte interface: An atomic force microscope study

► We modified an atomic force microscope (AFM) for controlling the electric potential of a flat sample and a tip in an electrolyte. ► and for measuring the interaction force between sample and tip down to nanometer separations. ► We found the effective dynamic viscosity close to surface and tip increasing by orders of magnitude with respect to bulk. ► and the effective viscosity at the interface being controlled by the applied electric potential.