Modulating Hydrogen Adsorption via Charge Transfer at the Semiconductor–Metal Heterointerface for Highly Efficient Hydrogen Evolution Catalysis

Designing and synthesizing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is important for realizing the hydrogen economy. Tuning the electronic structure of the electrocatalysts is essential to achieve optimal HER activity, and interfacial engineering is an effective strategy to induce electron transfer in a heterostructure interface to optimize HER kinetics. In this study, ultrafine RhP₂ /Rh nanoparticles are synthesized with a well-defined semiconductor-metal heterointerface embedded in N,P co-doped graphene (RhP₂ /Rh@NPG) via a one-step pyrolysis. RhP₂ /Rh@NPG exhibits outstanding HER performances under all pH conditions. Electrochemical characterization and first principles density functional theory calculations reveal that the RhP₂ /Rh heterointerface induces electron transfer from metallic Rh to semiconductive RhP₂ , which increases the electron density on the Rh atoms in RhP₂ and weakens the hydrogen adsorption on RhP₂ , thereby accelerating the HER kinetics. Moreover, the interfacial electron transfer activates the dual-site synergistic effect of Rh and P of RhP₂ in neutral and alkaline environments, thereby promoting reorganization of interfacial water molecules for faster HER kinetics.