One-Dimensional Porous Hybrid Structure of MoC-CoP Encapsulated in N-Doped Carbon Derived from MOF: An Efficient Electrocatalyst for Hydrogen Evolution Reaction over the Entire pH Range.

The development of outstanding noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) has attracted broad interest. Herein, a novel one-dimensional (1D) HER hybrid catalyst consisted of cobalt phosphide (CoP) and molybdenum carbide (MoC) nanoparticles wrapped by nitrogen-doped graphitic carbon (called CoP/MoC-NC) was successfully fabricated by a facile continuous-flow method and a simple two-step annealing process. During these processes, the successful synthesis of the MoO nanorods coated with cobalt zeolitic imidazolate frameworks (Co-ZIF-67) (Co-ZIF-67@MoO) through the continuous-flow method plays a key role. The as-synthesized CoP/MoC-NC hybrid electrocatalyst exhibits a significantly enhanced HER electrocatalytic activity over the entire pH range relative to that of the control materials CoP, MoC-NC, and physically mixed CoP and MoC-NC. The outstanding HER catalytic performance is mainly due to the fact that the electron cloud transfers from Co to Mo in CoP/MoC-NC through the Co-P-Mo bond, resulting in the formation of a high valence state for Co (Co) species and lower valence states for Mo (i.e., Mo, Mo) species, providing the abundant HER active sites. Moreover, the Gibbs free energy (Δ G) of CoP/MoC-NC obtained by the density function theory calculations indicates a good balance between the Volmer and Heyrovsky/Tafel steps in HER kinetics. Such a cobalt zeolitic imidazolate framework-mediated strategy depicted in this work offers an interesting perspective for developing highly efficient noble-metal-free electrocatalysts for hydrogen production.