Ligand Dissociation Mediated Charge Transfer Observedat Colloidal W18O49Nanoparticle Interfaces.

Understanding chargetransfer dynamics through the ligand shellof colloidal nanoparticles has been an important pursuit in solarenergy conversion. While charge transport through ligand shells ofnanoparticle films has been studied intensely in static dry and electrochemicalsystems, its influence on charge transfer kinetics in dispersed colloidalsystems has received relatively less attention. This work reportsthe oxidation of amine passivated tungsten oxide nanoparticles byan organically soluble tris-(1,10-phenanthroline) ironIIIderivative. By following the rate of this oxidation optically viathe production of the ferroin derivative under various reaction conditionsand particle derivatizations, we are able to show that the fluxionalligand shells on dispersed, colloidal nanoparticles provide a separateand more facile pathway for charge transfer, in which the rate-limitingstep for charge transfer is the ligand dissociation. Since such ligandshells are frequently required for nanoparticle stability, this observationhas significant implications for colloidal nanoparticle photocatalysis. [ABSTRACT FROM AUTHOR]