Metal-organic framework-derived highly active cobalt-nitrogen-carbon hybrid arrays for efficient hydrogen evolution reaction

The design of efficient catalysts with abundant active sites is fascinating but still is a great challenge for hydrogen evolution reaction (HER). Herein, a highly active cobalt-embedded nitrogen-doped carbon nanotube hybrid array on nickel foam (Co-NCNT/NF) was constructed to enhance the HER activity. The 3D hydroxide nanosheets were utilized as a template and reactant to form the ordered ZIF-8 array by a solid–liquid interfacial release of Zn ions and coordination reaction, and the growth of ZIF-67 on the surface of ZIF-8 arrays assures the introduction of cobalt species into the precursor, catalyzing the formation of active cobalt-nitrogen-carbon (Co-N-C) sites. Based on the structure analysis and density functional theory calculations, an optimal configuration of the cobalt (111) face coated by carbon layer with one Co atom coordination to one N and C reveals a multi-site nature of the designed Co-NCNT/NF catalyst, which provided the improved conductivity, 3D hierarchical structure, the uniform distribution, and efficient exposure of active Co–N-C sites. A small overpotential of 157 mV at a current density of − 10 mA cm−2 for HER in 1 M KOH was obtained, proving that the optimized proton adsorption on the multi-sites structure promotes the HER activity of Co-NCNT/NF.