Multi-Hierarchical Porous Mn-Doped CoP Catalyst on Nickel Phosphide Foam for Hydrogen Evolution Reaction

The rational designing of an electrocatalyst microstructure is an efficient route for the exposure of rich active sites and optimization of the reaction kinetics. In this study, manganese-modified cobalt phosphide (Mn-CoP) with a multi-hierarchical porous structure is prepared by phosphorizing a CoMn layer double hydroxide (LDH) nanosheet precursor, which is deposited on phosphorized nickel foam (NF-P) via a unipolar pulse electrodeposition (UPED) method at first. Herein, the NF-P endows a large porous frame structure, whereas the Mn-CoP layer is composed of reticular nanoplate arrays with a macropore structure and the Mn-CoP nanoplate is built by nanosheet arrays with a mesoporous structure. This multi-hierarchical porous structure benefits the diffusion of reactants and intermediate, as well as the generated gas. Consequently, the Mn-CoP/NF-P-based electrode exhibits an ultra-low overpotential of 69 mV at −10 mA cm–2 with a small Tafel slope of 84 mV dec–1. Moreover, it maintains a constant performance curve for at least 1000 cycles and shows an extreme long duration of at least 100 h even under a high current density (e.g., 100 mA cm–2).