RuO 2 -anchored, NiCo-embedded nitrogen-doped carbon nanofibers as a free-standing electrode for efficient alkaline hydrogen evolution

Abstract

Developing high-performance cathodes for alkaline water electrolysis requires the concurrent optimization of active sites, electron-transport pathways, and electrode architecture. In this work, we report a binder-free, free-standing electrode composed of RuO 2 -anchored, NiCo-embedded N-doped carbon nanofibers (RuO 2 -NiCo/NCNF) for the hydrogen evolution reaction (HER) in alkaline media. NiCo layered double hydroxide (LDH), derived from a Co-based zeolitic imidazolate framework (ZIF-67), was incorporated into electrospun polyacrylonitrile nanofibers and converted into a conductive carbon nanofiber network containing embedded NiCo alloy domains through stabilization and carbonization. These domains provide a favorable environment for the subsequent deposition-precipitation of Ru species, thereby enabling the facile introduction of RuO 2 onto the nanofiber surface. In 1.0 M KOH, RuO 2 -NiCo/NCNF exhibited overpotentials of 48 mV at |j| = 10 mA cm -2 and 208 mV at |j| = 100 mA cm -2 , outperforming NiCo/NCNF, RuO 2 -NCNF, pristine NCNF, and a commercial 10 wt.% Pt/C electrode (0.0385 mg Pt cm -2 ) under identical testing conditions. Furthermore, the electrode maintained stable operation for 50 h. This enhanced alkaline HER performance is attributed to the synergistic integration of amorphous hydrous RuO 2 and NiCo within a conductive and mechanically robust nanofiber scaffold, which promotes water dissociation, charge transfer, and active-site accessibility. These results demonstrate a promising strategy for designing durable and efficient free-standing HER electrodes for alkaline water splitting.