MOF-derived cobalt-embedded nitrogen-doped mesoporous carbon leaf for efficient hydrogen evolution reaction in both acidic and alkaline media

Abstract

Metal-embedded nitrogen-doped carbon materials have been proposed as novel hydrogen evolution reaction (HER) catalysts to replace platinum-based materials, while these alternatives usually exhibit low activity and gradual deactivation during their use. Here, leaf-like cobalt-embedded nitrogen-doped porous carbon sheet (Co-NC) for the HER is obtained by simple pyrolysis of a two-dimensional metal organic framework. The Co-NC annealed at 800 °C exhibits large surface area and the active metallic cobalt species embedded in the N-doped carbon layers, which leads to the lower overpotential, higher current density, and superior durability in alkaline media. However, the Co-NC annealed at 600 °C shows abundant nitrogen-coordinated cobalt species, which favors the high HER activity under acidic condition. These structural properties of the Co-NC enable the efficient HER activity by increasing the active sites and enhancing mass transfer of water molecules or protons at the interface where the reaction takes place.