CoSe₂ necklace-like nanowires supported by carbon fiber paper: A 3D integrated electrode for the hydrogen evolution reaction

Pyrite-type CoSe₂ necklace-like nanowires (NWs) were successfully grown on carbon fiber paper (CFP) and proven to be an efficient electrocatalyst towards the hydrogen evolution reaction (HER). By combining the use of mesoporous CFP and the nano-structuring of the electrocatalyst, the highly active CoSe₂ necklace-like NWs on CFP only need the modest overpotentials of 188 and 199 mV to afford the current densities of 50 and 100 mA cm^-2, respectively. A small Tafel slope of 34 mV dec^-1 and a charge transfer resistance of 7.05 Ω illustrate the prominent electrocatalytic performance. After continual electrolysis for 20 h or conducting cycling for 5000 times, the high activity of CoSe₂ NWs toward the HER is still perfectly preserved. The outstanding electrocatalytic performance and stability make the CoSe₂ necklace-like NWs on CFP a promising earth-abundant electrocatalyst for the HER and other renewable energy applications.