Self-assembled Ni2P/FeP heterostructural nanoparticles embedded in N-doped graphene nanosheets as highly efficient and stable multifunctional electrocatalyst for water splitting

Abstract

It is extremely crucial to explore nonprecious multifunctional electrocatalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and particularly overall water splitting with high efficiency and excellent stability for future renewable energy generation. Herein, for the first time, a “self-assembly and self-template” strategy is adopted to fabricate self-assembled Ni2P/FeP heterostructural nanoparticles embedded in N-doped graphene nanosheets (NFP@NG) via a facile and cost-effective approach. The bimetallic NFP heterostructure embedded into NG presents far better water splitting performance than single-component counterparts. Notably, the NFP@NG hybrid exhibits enhanced HER performance with low onset potentials of −110 and −144 mV along with low overpotentials of −250 and −240 mV at 10 mA cm−2 in alkaline and acid electrolytes, respectively. In addition, the hybrid displays superior OER properties with a low overpotential of 295 mV@10 mA cm−2, a small Tafel slope of 59.1 mV dec−1 and remarkable long-term cycling durability. Furthermore, when employed as both cathode and anode for overall water splitting, NFP@NG yields a remarkable long-term stability of 24 h with a low cell voltage (1.69 V) at 10 mA cm−2. The remarkable multifunctional electrocatalytic properties can be attributed to the unique and novel architecture constructed by well-dispersed Ni2P/FeP heterostructural nanoparticles embedded in highly conductive few-layer NG nanosheets, which can not only lead to a uniform growth of phosphides with a large effective surface area and enable full utilization of electroactive sites, but also greatly accelerate the electron transfer and ion diffusion. This work presents a “self-assembly and self-template” strategy to synthesize nonprecious bi-metallic phosphide heterostructure/N-doped graphene nanosheets as promising multifunctional electrocatalyst for water splitting.