Self-supported system of MoO₂@Ni₂P heterostructures as an efficient electrocatalyst for hydrogen evolution reactions...

Efficient, stable and low-cost catalysts are essential for improving the efficiency of hydrogen evolution reactions. Herein, the MoO₂@Ni₂P heterostructure electrocatalyst was synthesized in a self-supported system on a carbon paper (CP) by two-step deposition and phosphorization at low temperature. The self-supported nanoarray structure makes the catalyst to effectively and efficiently transfer electrons and exposes more of its active sites. Moreover, the strong interaction between Ni₂P and MoO₂ helps to effectively optimize the electronic structure. The density of states calculations demonstrate that there is an increase in the density of electronic states near the MoO₂/Ni₂P Fermi level. This shows that MoO₂/Ni₂P has fast charge transfer kinetics. MoO₂ modulates the d-band center of nickel, resulting in moderate adsorption/desorption of hydrogen. The above results show that MoO₂@Ni₂P has good hydrogen evolution activity. The experimental results show that the overpotential (η₁₀) of MoO₂@Ni₂P/CP in the alkaline environment is only 57 mV with a Tafel slope of 61 mV dec^-1. It is similar to the commercial noble-metal catalysts and outperforms most reported catalysts.