Robust Sandwiched B/TM/B Structures by Metal Intercalating into Bilayer Borophene Leading to Excellent Hydrogen Evolution Reaction

Bilayer borophene, very recently synthesized on Ag and Cu, possesses an extremely flat large surface and excellent conductivity. The van der Waals gap of bilayer borophene can be intercalated by metal atoms, tailoring the properties of bilayer borophene. Herein, sandwiched B/TM/B (transition metal, TM = Co, Ni, Cu, Pd) is proposed as a new 2D formation with both energetic, structural, and thermal stability by TM atoms intercalated into bilayer borophene. In addition, it is a novel platform for the electrocatalytic hydrogen evolution reaction (HER). The intercalation metal atom serves as a single-atomic catalyst. The TM is protected by outside boron layers from being corroded by acidic/alkaline solutions. B/Cu-x/B, B/Pd-x/B, and B/Al-x/B with different metal coverage exhibit defect-independent extremely low HER free energy in the range of approximately -0.162 to 0.179, -0.134 to 0.183, and -0.082 to 0.086 eV which are comparable to the noble metal Pt. Combining excellent conduction, high structural and thermal stability, low resistance to intercalated behavior, an effortless water splitting process, excellent defect-independent catalytic performance, cheapness and abundance of raw materials, and corrosion resistance, 2D sandwiched B/TM/B (TM = Co, Ni, Cu, Pd) is believed to be promising for electrocatalysis applications.