Self-Grown Carbon Nanotube Encapsulated Co Nanoparticle Compound Fe-Nx/Mesoporous Carbon as Bi-Functional Electrocatalyst to Drive Efficient Electrochemical Overall Water Splitting

Electrochemical overall water splitting is one of the main choices to realize hydrogen energy. In this study, a simple strategy of self-growth of carbon nanotubes with the tip end of Co nanoparticles compound Fe-Nx/mesoporous carbon as bi-functional electrocatalyst is proposed. At high temperature, cobalt nanoparticles catalyze the self-growth of nitrogen-doped carbon nanotubes with a tip of cobalt particles from a metal-organic framework ZIF-8. FeTAPc as Fe and N resource is further adsorbed on the shell and then re-carbonized under 900°C to fix Fe-Nx on the polyhedron carbon shell to form bi-functional electrocatalyst (Fe-Nx/Co-NC-900). Fe-Nx/Co-NC-900 showed good OER (330 mV) and HER (239 mV) overpotential. As a result, the porous structure of Fe-Nx/Co-NC-900 and the interconnected three-dimensional carbon network promote the material transport. The self-growing carbon nanotubes improve the conductivity of the electrocatalyst and avoid aggregation. The high dispersion of two kinds of metal atoms and the mixed growth of metal nanoparticles co-endowed Fe-Nx/Co-NC-900 electrocatalyst with rich activity. In addition, Fe-Nx/Co-NC-900 has been used to assemble an electrochemical overall water splitting with a driving voltage of 1.67 V, which shows its practical application in electrochemical overall water splitting. This study provides enlightenment in application of hydrogen energy production.