A process of treating metal oxide nanoparticles that includes mixing metal oxide nanoparticles, a solvent, and a surface treatment agent that is preferably a silane or siloxane is described. The treated metal oxide nanoparticles are rendered hydrophobic by the surface treatment agent being surface attached thereto, and are preferably dispersed in a hydrophobic aromatic polymer binder of a charge transport layer of a photoreceptor, whereby .pi.--.pi. interactions can be formed between the organic moieties on the surface of the nanoparticles and the aromatic components of the binder polymer to achieve a stable dispersion of the nanoparticles in the polymer that is substantially free of large sized agglomerations.