Irreversible electrostatic deposition of Prussian blue from colloidal solutions

Abstract

Prussian blue (PB) can be deposited from colloidal solutions (5.4 × 10−3 molPB L−1, 0.01 mol L−1 KNO3) on glassy carbon, either by potential cycling or potentiostatically, provided that the deposition potential is more positive than −0.2 V vs. Hg/Hg2Cl2. Depending on the deposition potential, the PB particles form either a single layer of Everitt’s salt, of PB, or multilayers of Berlin green. Also depending on the electrode potential, the deposition was accompanied by currents which were either only of capacitive nature, or represent the sum of capacitive and faradaic currents. The currents were always limited by the diffusion of the colloidal particles to the electrode surface, i.e., they obeyed the Cottrell equation. The PB layers were characterized by in situ atomic force microscopy.