Stabilizing Atomically Thin Pt (111) Metallene and Its Derivatives by Coupling with a Unique CP Nonmetallic Framework for Efficient HER Catalysis

Despite outstanding catalytic potential, stabilizing single-atom-thick metallenes presents a fundamental challenge in materials design. Through first-principles structure search calculations, we have identified a novel two-dimensional (2D) Janus nanomaterial Pt(111)@CP, in which the single atomic Pt (111) metallene layer serves as one exposed surface, effectively stabilized by coupling with the robust nonmetallic CP framework composed of sp³-hybridized C atoms and sp³-hybridized P atoms possessing lone pair electrons. The unique Pt(111)@CP nanostructure can exhibit excellent dynamic, thermodynamic, mechanical and thermal stability, as well as metallic conductivity. Additionally, it can demonstrate considerably high HER catalytic performance, with both sides playing important roles. Remarkably, it can maintain high HER catalytic activity over a wide range of θ_H* coverages. Its active site density can reach 1.022 × 10¹⁶ sites/cm², exceeding many reported materials and even state-of-the-art Pt. Further, by substituting Pt atoms with other Group VIII transition metals, we derived a series of novel 2D Janus TM(111)@CP monolayers (TM = Ru, Rh, Pd, Os and Ir) from the Pt(111)@CP structure. All five newly designed TM(111)@CP monolayers featuring the TM (111) metallene surfaces demonstrate high stability and metallic conductivity. They also maintain high HER catalytic activity over a wide range of θ_H* coverages, with active site densities reaching 1.473 × 10¹⁵ to 9.888 × 10¹⁵ sites/cm², comparable to or exceeding the precious metal Pt. The relevant catalytic mechanisms are analyzed. This study presents an innovative strategy for stabilizing metallenes and developing high-performance metallene-related electrocatalysts for HER and even broader energy conversion applications.