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Highly porous Ni films have been potentiostatically synthesised by micelle-assisted electrodeposition using custom-made PS-b-P4VP block copolymer micelles as a soft template. Two PS-b-P4VP block copolymers with PS/P4VP block ratios of 1:1 and 1:4 were used for the micelle-assisted electrodeposition, resulting in Ni films with large pores of diameters varying from 25 to 600 nm (1:1), and from 10 to 230 nm (1:4). As a result of the interconnected porosity, and hence the drastic increase of the surface-to-volume ratio, the electrocatalytic performance at hydrogen evolution reaction (HER) in alkaline media is significantly improved in comparison to a dense Ni film, and—more importantly—even in comparison to a highly mesoporous Ni film with monodisperse 10 nm wide pores. Most remarkably, it is discovered that the openly porous Ni electrocatalysts not only lead to a simple increase in HER current density, but also to a lower overpotential and a better long-term performance. While the bulk of the films is metallic, Ni(OH)2 is formed on the surfaces of all Ni films during HER. This effect leads to an initial decrease of the catalytic activity, but provides excellent stability in alkaline media. The presented synthesis process for pure Ni may be readily adopted to any other electroplatable metals and alloys This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101058076 and the Marie Skłodowska-Curie grant agreement No 764977. Additional funding was obtained from the Generalitat de Catalunya under project 2017-SGR-292 and the Spanish Government under PID2019–108794 GB-I00, PID2020–116844RB-C21, and associated FEDER Project. KE acknowledges the Spanish Ministerio de Uni- versidades for a Margarita Salas fellowship, financed by the European Union – NextGenerationEU. AGC acknowledges financial support from the Spanish Ministry of Science through the “Severo Ochoa” Programme for Centres of Excellence (FUNFUTURE, 2020–2023) |
