Flexible and porous catalyst electrodes constructed by Co nanoparticles@nitrogen-doped graphene films for highly efficient hydrogen evolution

The development of electrodes composed of non-noble-metal catalysts with both excellent activity and high stability for the hydrogen evolution reaction (HER) is essential for hydrogen production. In this work, a flexible and robust film electrode based on cobalt nanoparticles embedded into the interlamination of N-doped graphene film (Co@NGF) is fabricated by simple vacuum filtration combined with subsequently controlled calcination. This flexible three-dimensional (3D) nano-architecture film directly used as the electrode shows a low onset potential of only 14 mV (vs. RHE) with a small Tafel slope of 93.9 mV per dec for the HER in 0.5 M H2SO4. Stability tests through long term potential cycles and extended electrolysis confirm the perfect durability of Co@NGFs in acid media. The remarkable HER catalytic activity is derived from the electron penetration effect of cobalt nanoparticles as the core protected by N-doped graphene as the shell. It is worth noting that the Co@NGF electrodes, for the first time, used as both the anode and cathode in a two-electrode system open up new possibilities for exploring overall water splitting catalysts in an acid electrolyte. This development offers an attractive HER film electrode for large-scale water splitting technology.