Metal–Organic Framework Derived Carbon Nanotube Grafted Cobalt/Carbon Polyhedra Grown on Nickel Foam: An Efficient 3D Electrode for Full Water Splitting

The growth of metal–organic framework (ZIF‐67) nanocrystals on nickel foam (NF), followed by carbonization in diluted H 2 , leads to a nitrogen‐doped carbon‐nanotube‐grafted cobalt/carbon polyhedra film on NF. The obtained material serves as a highly active binder‐free electrocatalyst for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), enabling high‐performance alkaline (0.1 m KOH) water electrolysis with potentials of 1.62 and 0.24 V, respectively, at OER and HER current densities of 10 mA cm −2 .