Nanoarchitectonics of borophene via fluorination-mediated transition-metal doping for oxygen evolution electrocatalysis

Borophene is a polymorphic metallic Xene with record electronic mobility in its β₁₂ phase, which exhibits record electronic mobility and Young’s modulus along its ridgelines, which are indeed better than graphene which renders it a unique quantum material, extremely useful for numerous frontline applications including ultrafast electronic chips, wearable electronic gadgets, THz electronics and ultrafast sensors. With atomic vacancies in its lattice, a unique feature in borophene among all Xenes, enables its edge atoms to be catalytically active, and therefore, it is deemed as the next generation electrocatalyst. Transition metal doping can help inject electrons into the borophene lattice which inherently lacks electrons, thereby enabling it for catalytic performance. However, it is extremely challenging to substitutionally dope borophene due to strong lattice binding. Here, we demonstrate a fluorination-mediated controlled approach employing exotic thermodynamic conditions which enables facile, tunable doping of borophene, producing Fe-doped (Fe-FB1, Fe-FB2, Fe-FB3), Ni-doped (Ni-FB1, Ni-FB2, Ni-FB3), and FeNi-codoped fluoroborophene (FeNi-FB) electrocatalysts. Notably, the FeNi-FB co-doped catalyst exhibits a synergistic enhancement in oxygen evolution reaction (OER) activity, delivering a low overpotential of 0.274 V at 10 mA cm⁻², compared with 0.306 V and 0.310 V for Fe-FB and Ni-FB, respectively. Post-OER characterizations established robust FeNi-FB electrodes under alkaline condition catalytic performance. These findings establish fluorination-mediated doping as an efficient strategy for engineering high-performance borophene-based electrocatalysts.