In this project, we combine the development of nanoimprint technology towards smaller sizes as well as tailored plasmonic properties with studies on photoelectrochemical CO₂ reduction. The project thus aims at making contributions to current challenges in nanotechnology and fundamental aspects of artificial photosynthesis. Nanoimprint procedures will be developed allowing for the fabrication of regular and well defined metal arrays with feature sizes beyond the current state of the art or with sharp edges and small structure distances on semiconductor substrates. The latter are designed for maximum plasmonic field enhancement and procedures are optimized for easy plasmon resonance frequency adjustment. The arrays extend over macroscopic dimensions and shall be used in electrochemical studies on CO₂ reduction. Here, fundamental properties of the semiconductor| metal nanostructure|electrolyte interface will be examined. In particular, two so far unconsidered physical effects will be investigated: (1) The coupling of plasmonic excitations to molecular vibrations, and its impact on the reactivity and selectivity of the system; (2) The enhancement of reaction rates on the nanoscale by molecular fluctuations. Furthermore, our studies include an experimental survey of structure size and other parameters on the efficiency and selectivity of the reaction, and simulations of the interface with a continuum approach. The project thus has the potential to advance future device fabrication processes and to elucidate novel reaction paths for efficient CO₂ reduction.