The work by Moskovits and colleagues was built on the idea that the excitations of collective electron oscillations, also known as local surface plasmons, in metal materials can generate hot charge-carriers that can then be used to boost the efficiency of photocatalytic processes. The generation of hot electrons in metals does not require the same amount of energy needed for the formation of electron–hole pairs in semiconductors. Furthermore, the use of metal nanostructures helps to avoid charge recombination. In such confined spaces, electrons can rapidly diffuse to the surface of the nanostructure, and be easily injected in the conduction band of a semiconductor placed at the interface with the metal. Based on these principles, Moskovits and co-workers proposed a device in which some areas of a Au nanowire are covered by a Pt-decorated TiO2 film and others by a Co-based catalyst (pictured). Upon irradiation with visible light, the hot electrons generated in the Au nanowires migrate toward the TiO2 film where they are absorbed by the Pt nanoparticles and used to reduce hydrogen ions. On the other side, the holes on the Au nanowires are filled in by electrons from the Co-based catalyst, which in turn can catalyse the water oxidation reaction.