Interface Charge Engineering of Ultrafine Ru/Ni2P Nanoparticles Encapsulated in N,P-Codoped Hollow Carbon Nanospheres for Efficient Hydrogen Evolution

Adjusting the charge environment and charge transfer to optimize the hydrogen absorption free energy (ΔGH*) is an effective strategy to improve the intrinsic activities of electrocatalysts toward the hydrogen evolution reaction (HER). Herein, ultrafine Ru/Ni2P nanoparticles (NPs) with quantum dot interfaces encapsulated in N,P-codoped hollow carbon nanospheres (Ru/Ni2P@NPC) are prepared through a two-step process including carbonization and subsequent phosphorization. First, hollow polymer spheres impregnated with a homogeneous solution of Ni2+ and Ru3+ ensure good dispersion and close contact of Ru and Ni metals at the quantum dot scale (∼3 nm) after the carbonization process. The subsequent oriented phosphorization toward Ni in Ru/Ni metals successfully yields quantum dot interfaces composed of Ru, Ni2P, and NPC, and the intimate contact of these species usually induces strong electronic interactions on their interfaces, thus leading to an optimized ΔGH* and enhanced intrinsic activity. Moreover, unique N,P-codoped hollow carbon nanospheres provide a large Brunauer–Emmett–Teller surface area, high conductivity, and ultrathin carbon layers as a protection cap. The as-prepared Ru/Ni2P@NPC possesses remarkable activity and durability for the HER, which exhibits low overpotentials of 89, 124, and 132 mV to afford a current density of 10 mA cm–2 in acidic, neutral, and alkaline media, respectively. Therefore, our work provides a facile way to enhance the intrinsic activities of active species for the HER through regulating the interface charge distribution.