Transition-Metal Phosphide-Carbon Nanosheet Composites Derived from Two-Dimensional Metal-Organic Frameworks for Highly Efficient Electrocatalytic Water-Splitting.

Abstract

The preparation of highly active, sustainable, nonprecious metal materials as hydrogen evolution and oxygen evolution reaction (HER and OER) catalysts that can relieve the environmental pollution and energy shortage problems present a great challenge to chemists. We herein report the fabrication of a highly active metal phosphide-carbon composite catalyst for HER and OER in acid and basic solution, respectively. The catalyst is derived through carbonization and subsequent phosphorization of two-dimensional (2D) cobalt porphyrinic metal-organic framework nanosheets. It consists of cobalt phosphide nanoparticles embedded in mesoporous N-doped graphitic carbon materials. The catalyst shows good electrocatalytic activities for HER in 0.5 M H2SO4 and OER in 1 M KOH with overpotentials of 98 and 370 mV at a current density of 10 mA cm-2 and the Tafel slopes of 74 and 79 mV dec-1, respectively. In addition, the catalyst also shows good durability. The method used in this study could be applied to prepare new, highly efficient water-splitting catalysts by using diverse 2D metal-organic frameworks as templates.