3D multi-site hydrogen evolution reaction catalysts on nanoimprinted surfaces, structured via multi-photon lithography derived masks

• Nanoimprinting can replicate submicron precise multi-photon polymerized features. • Structured Ni thin film electrodes derived from imprinted polymer surfaces. • Surface structuring decreased the hydrogen evolution overpotential by up to 10%. • Surface structure characteristics did not influence the hydrogen evolution reaction. Efficient water splitting is a major challenge in green hydrogen production and energy transition. Thus, considerable scientific efforts are devoted to optimize surface geometries for enhancing the performance of water-splitting catalysts. The current study aims to develop a reliable and facile 3-step (re-)production technique for manufacturing structured surfaces by combining multi-photon lithography (MPL) and nanoimprint lithography (NIL). MPL enables structuring of high-definition micrometer-scale surface geometries. A variation of these topologies was used as masks for replication by NIL. Thus, molds were derived to emboss the original nanostructured topologies repeatedly into a UV-curable resin. Subsequently, a Ni thin film metallization was deposited by physical vapor deposition onto the final imprinted polymeric structures, thereby realizing topologically structured conductive electrodes. To demonstrate the applicability of this elaborated technique, the catalytic activities towards the hydrogen evolution reaction were assessed for different surface geometries. An increase in catalytic performance was achieved through surface enlargement by structuring, whereby a direct contribution of the specific structure geometry was not evident. This elegant method is highly versatile and scalable for producing a wide range of structured functional surfaces on a lab scale, as demonstrated for the water splitting reaction, with results transferable to an industrial scale.