MOF-Derived Formation of NiP-CoP Bimetallic Phosphides with Strong Interfacial Effect toward Electrocatalytic Water Splitting.

Bimetallic phosphides have attracted research interest for their synergistic effect and superior electrocatalytic activities for electrocatalytic water splitting. Herein, a MOF-derived phosphorization approach was developed to produce NiP-CoP bimetallic phosphides as bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). NiP-CoP shows superior electrocatalytic activities to both pure NiP and CoP toward HER and OER, revealing a strong synergistic effect. High-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy elemental mapping analysis show that, in the sample NiP-CoP, the NiP and CoP nanoparticles with an average particle size 10-20 nm were mixed closely on the nanoscale, creating numerous NiP/CoP interfaces. By comparison with the sample NiP+CoP, in which seldom NiP/CoP interfaces exist, we documented that the NiP/CoP interface is an essential prerequisite to realize the synergistic effect and to achieve the enhanced electrocatalytic activities in NiP-CoP bimetallic phosphides. This finding is meaningful for designing and developing bicomponent and even multicomponent electrocatalysts.