Constructing Transition Metal Single-Atom-Modified MoB2: Extraordinary Electrocatalytic Hydrogen Evolution and Mechanism Investigation

Developing single-atom catalysts (SACs) and exploring the interaction between a single atom and support are crucial for identifying the active centers, clarifying the catalytic mechanisms, and deepening understanding of SACs. Herein, by employing Anderson-type POMs as molecular precursor, a series of transition metal (TM = Ni, Co, Fe) single atoms anchored on MoB2 (TM-MoB2) with high TM loading (∼6.91 wt %) are prepared. The decoration of TM promotes the electrocatalytic hydrogen evolution activity of MoB2, of which Ni-MoB2 delivers the best performance in both alkaline and acidic solutions, outperforming most TM boride-based catalysts. Density functional theory simulation reveals that the introduction of Ni single atoms endows the top Mo on the Ni-MoB2 surface with low water dissociation barrier (∼0.62 eV) and optimal H adsorption Gibbs free energy (∼0.02 eV), thus exhibiting remarkable hydrogen evolution activity. This work offers a versatile strategy for preparing TM-MoB2 SACs and paves the way to recognize SACs with a new support platform.