Hot electron photo-charging and electrochemical discharge kinetics of silver nanocrystals

Chronopotentiometry and chronoammperometry methods are used to study the photocharging and electrochemical discharging of Ag nanocrystals on indium tin oxide (ITO) substrates. The photocharging is initiated by Ag plasmon electronic excitation, which causes the oxidation of surface-bound citrate ions. In aqueous citrate solution, the particles discharge by reducing hydrogen. When silver ions are introduced, silver reduction increases the rate of discharge. The electrochemical kinetics is modeled quantitatively using the Butler-Volmer equation. The capacitance of the particle electrode is experimentally determined to be similar to 2.22 x 10(-4) C/V. We conclude that high-quantum-yield surface photochemistry and photocharging is possible for well-formed nanocrystals.