Asymmetric Modification of TiO2 Nanofibers with Gold by Electric-Field-Assisted Photochemistry

We present a new procedure for the site-specific deposition of metal on semiconductor nanofibers (NF). The semiconductor NFs are exposed to an external electric field while irradiated with UV light. This coupling allows the generation of excited electron- hole couples and drives them to the opposite extremities of the fibers where they can react with redox species in solution. We demonstrate here that, when both UV light and electric field are simultaneously applied, a metal deposit is formed at the cathodically polarized tip of the NF in a controlled way. Such an electric-field-assisted photochemical (EFAP) process is suitable for highly localized photodeposition of metals, leading to semiconductor Janus objects.