Ru Modulation Effects in the Synthesis of Unique Rod-like Ni@Ni₂P–Ru Heterostructures and Their Remarkable Electrocatalytic Hydrogen Evolution Performance

The construction of highly efficient and stable Pt-free catalysts for electrochemical hydrogen generation is highly desirable. Herein, we demonstrate the first metal-phosphides-metal system consisting of Ru, Ni₂P, and Ni, which forms unique multiheterogeneous Ni@Ni₂P-Ru nanorods. Interestingly, a Ru modulation effects that promotes the desorption of H₂ to achieve a moderate hydrogen adsorption energy (ΔG_H), and enables the formation of Ni@Ni₂P nanorods via Ru-Ni coordination to enhance the conductivity was discovered. Due to its optimal ΔG_H, improved conductivity and rod-like morphology, this catalyst shows superior electrocatalytic HER performances in both acidic and alkaline conditions, which are superior to those of some recently reported phosphides and close to that of commercial 20% Pt/C. Such a design strategy is not limited to Ni₂P and Ru but also may be extended to other similar phosphides and noble metals, providing a new promising approach and an alternative to Pt catalysts for electrocatalytic applications.