Photophysical Effects behind the Efficiency of Hot Electron Injection in Plasmon-Assisted Catalysis: The Joint Role of Morphology and Composition

Plasmonic materials have been intensively used in order to extend the photoactivity of large band gap semiconductors into the visible light region. In this framework, the present study examines the joint role played by the morphology and composition of plasmonic nanoparticles in their photosensitizing capabilities. The critical influence of these parameters is evidenced by analyzing the effect of Au and core-shell Au@Ag nanorods on a TiO2-driven photochemical probe reaction. In this case, the use of the bimetallic composites leads to a remarkable increase in the photocatalytic activity of the semiconductor compared to that found for the monometallic Au sensitizers. The mechanism behind this observation has then been computed theoretically in order to establish the physical reasons for such an acceleration. At this point, it is found that in terms of hot electron injection, the contribution of the transversal modes of the Au@Ag NRs together with low damping of these nanostructures are responsible for the s...