Among multicomponent hybrid nanostructures, nanocatalysts composed of a metal-semiconductor junction provide an interesting platform to study the role of metal-oxide interfaces and hot electron flows in heterogeneous catalysis. In this talk we show that hot carriers generated upon photon absorption significantly impact the catalytic activity of CO oxidation. Pt-CdSe-Pt nanodumbbells were prepared by the selective growth of metal tips onto semiconductor quantum rods. CO oxidation was carried out on Pt-CdSe-Pt nanodumbell arrays under light irradiation or dark conditions, respectively. We found that the Pt-CdSe-Pt nanodumbbells exhibited a higher turnover frequency by a factor of two during irradiation by light with energy higher than the bandgap of CdSe, while the turnover rate on bare Pt nanoparticles did not change, regardless of the light conditions. The electrical properties and the bandgap of CdSe were characterized separately with conductive probe atomic force microscopy. We suppose that hot electrons are generated upon the absorption of photons by the semiconducting nanorods, whereafter the hot electrons were injected into the Pt nanoparticles, resulting in the change in catalytic activity.