Self-organized silver nanostructures were grown in porous Si/SiO 2 matrix fabricated by ion track technology. The different silver nanostructures with shapes like "sunflowers", "azalea" or "corn" were realized by applying wet-chemical electroless deposition. We show that reproducible self-organized silver "sunflower" like nanostructures provide a high enhanced Raman signal of Nile blue dye molecules. Signal enhancement for a few or even just a single silver "sunflower" is demonstrated by analyzing the surface-enhanced Raman signature of Nile blue dye molecules. According to this, the silver nanostructures can act as efficient surfaces for surface enhanced Raman spectroscopy as well as (bio)-sensor applications.

The combination of CdSe nanoparticles as photosensitizers with [FeFe]-hydrogenase mimics is known to result in efficient systems for light-driven hydrogen generation with reported turnover numbers in the order of 10 4 -10 6 . Nevertheless, little is known about the details of the light-induced charge-transfer processes. Here we investigate the timescale of light-induced electron transfer kinetics for a simple model system consisting of CdSe quantum dots (QDs) of 2.0 nm diameter and a simple [FeFe]-hydrogenase mimic adsorbed to the QD surface under non-catalytic conditions. Our (time-resolved) spectroscopic investigation shows that both hot electron transfer on a sub-ps timescale and band-edge electron transfer on a sub-10-ps timescale from photoexcited QDs to adsorbed [FeFe]-hydrogenase mimics occurs. Fast recombination via back-electrontransfer is observed in the absence of a sacrificial agent or protons, which, under real catalytic conditions, would quench remaining holes or could stabilize the charge separation, respectively.

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