Hydrogen Evolution Reaction Activity of Electrochemically Exfoliated Borophene

Borophene has been theoretically shown as an active catalyst for hydrogen evolution reaction (HER). However, there are a few experimental studies assessing the HER activity of borophene. Herein, we study for the first time HER activity of electrochemically exfoliated borophene in acidic medium. Borophene sheets obtained by anodic exfoliation of crystalline boron particles in Na 2 SO 4 have β-rhombohedral crystal structure with an oxidized surface. Borophene exhibits notably higher catalytic activity compared to bulk boron with an overpotential of 480 mV at 10 mA cm −2 and a Tafel slope of 163 mV dec −1 . The superior activity of borophene is attributed to enhanced HER kinetics as well as increased electrochemical surface area. Our study provides encouraging results for the use of borophene in catalysis applications. Graphical Abstract