Technical University of Munich Chair of Nanoelectronics, Theresienstraße 90, 80333 München www.nano.ei.tum.de, Fax: +49 (0) 89 289 25337 Tuning of imprinting stamps for the fabrication of nano-electrodes for electrochemical CO2 reduction Matthias Golibrzucha, Thomas Maierb, Simon Filserc, Werner Schindlerd, Katharina Krischere, Markus Bechererf amatthias.golibrzuch@tum.de, bthomas.maier@ph.tum.de, csimon.filser@tum.de, dwerner.schindler@mytum.de, ekrischer@ph.tum.de, fmarkus.becherer@tum.de Facing global climate change, one of the most important goals is to reduce the concentration of CO2 in our atmosphere. The photoelectrochemical reduction of CO2 to climate neutral (solar) fuels is a hot topic in current research. One path to improve the photocatalytic efficiency is to employ large area, nanostructured electrodes. We use lift-off nanoimprint lithography (LO-NIL) to fabricate nano-structured electrodes for CO2 reduction experiments. In contrast to other nano-lithography techniques, such as electron beam lithography, LO-NIL enables the fast patterning of identical metal nanoisland arrays over large areas [1]. With our imprinting stamps, we are able to produce arrays with feature sizes of 1400nm, 350nm, 200nm and 75nm. Electrochemical investigations of these electrodes show that their electrochemical behavior changes drastically with the size of the nanoislands. We observed an increase in catalytic activity with decreasing nanoisland size [2]. Furthermore, the product distribution of the electrochemical CO2 reduction reaction, catalyzed by the metal nanostructures changes with their size. To further investigate the underlying mechanism, a stepless tuning of the meal nanoislands is required. Using different etching techniques, we are able to reproduce our imprinting stamps in SiO2. During this reproduction process, the feature size of the stamp can be tuned. The tunability allows analyzing the impact of a changed geometry (such as electrode filling factor, and different aspect ratios of the metal nanoisland circumference and its area) on the electro-chemical reactions and their mechanisms. Overall, the geometrical tuning of nano-electrode features provides further understanding of the reaction mechanisms of electrochemical CO2 reduction. References: [1] R. D. Nagel et al., “Nanoimprint methods for the fabrication of macroscopic plasmonically active metal nanostructures,” J. Appl. Phys., vol. 121, no. 8, p. 084305, Feb. 2017. [2] S. Filser et al., “Photoelectrochemical reactivity of well-defined mesoscale gold arrays on SiO2/Si substrates in CO2-saturated aqueous electrolyte,” Electrochim. Acta, vol. 268, pp. 546–553, 2018.      «

Technical University of Munich Chair of Nanoelectronics, Theresienstraße 90, 80333 München www.nano.ei.tum.de, Fax: +49 (0) 89 289 25337 Tuning of imprinting stamps for the fabrication of nano-electrodes for electrochemical CO2 reduction Matthias Golibrzucha, Thomas Maierb, Simon Filserc, Werner Schindlerd, Katharina Krischere, Markus Bechererf amatthias.golibrzuch@tum.de, bthomas.maier@ph.tum.de, csimon.filser@tum.de, dwerner.schindler@mytum.de, ekrischer@ph.tum.de, fmarkus.bechere...     »