Employing dual-ligand co-coordination compound to construct nanorod-like Bi-metallic (Fe, Co)P decorated with nitrogen-doped graphene for electrocatalytic overall water splitting

Abstract

Transition metal phosphide (TMP) has been investigated as promising non-precious electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting; however, its catalytic activity for OER and its long-term stability are far from satisfactory. So, it is still challengeable to synthesize TMP-based electrocatalysts with both highly efficient and stable HER and OER performance. Herein, for the first time, we develop a novel bimetallic phosphide/graphene hybrid catalyst, constructed by transforming dual-ligands co-coordination compound into nanorod-like(Fe,Co)P decorated with N-doped graphene nanosheets (DLC FCP@NG), synthesized via a facile room-temperature co-coordination reaction followed by phosphorization process. The DLC FCP@NG hybrid delivers outstanding electrocatalytic performance for OER (or HER) with an overpotential of 269 mV (or 189 mV) @10 mA cm−2, and a lower Tafel slop of 49.2 mV dec−1 (or 66.7 mV dec−1); moreover, being both anode and cathode for water splitting, it requires only a relatively low voltage of 1.63 V to deliver a current density of 10 mA cm−2, and displays outstanding stability over 30 h. The synthetic strategy and design idea of this work can be extended to design and synthesize other low-cost, novel and high effective multi-metal phosphide-based catalysts with greatly enhanced performance for overall water-splitting.