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(600:[600]600) Sylwester Gawinkowski opened a general discussion of the paper by Jorge Salmon-Gamboa: Why you are using SiO 2 nanoparticles? Do they have any function or are they only the substrate to attach other active nano-particles to? You have shown that only gold nanoparticles attached to silica nanoparticles do not inuence the rate of reaction signicantly. You have also demonstrated that adding platinum decorations on the gold nanoparticles causes a strong increase in the reaction rate. The signicance of the gold nanoparticles would be more clearly shown with a simple experiment in which you have no gold nanoparticles but still have platinum decorations. Jorge Salmon-Gamboa replied: Silica nanoparticles were chosen as a nano-sized inert substrate for Au nanoparticles. This choice of substrate provides a larger surface area covered with the active Au-Pt nanoparticles, in contrast to the situation when the active particles are placed directly onto a at substrate. Aiming for applications, the SiO 2-Au-Pt nanoparticles can then in turn be attached onto a at surface, forming a solid device that can be submerged into water, avoiding the problem of water contamination by nanoparticles. The role of the Au nano-particles was investigated. Under illumination in the LSP spectral band (556-566 nm), SiO 2-Pt did not enhance the reaction rate. In contrast, under the same conditions, SiO 2-Au-Pt showed a considerably enhanced rate, proving that hot carriers were generated in Au (see Fig. 1 below). (601:[601]601) Yuri Diaz Fernandez continued the discussion: I have two questions: (1) Can you comment on the dispersity of the size distribution of metal and SiO 2 particles and how well controlled are these in your system?