Asymmetric distortion of orbital hybridization at halogen-doped IrO2 monolayers for acidic water electrolysis

The unsatisfactory reactive activity and structural stability in acidic oxygen evolution reaction (OER) have been the main bottleneck in exploiting hydrogen energy from water splitting. Herein, we suggest a halogen (H)-doping strategy in 1T phase iridium dioxide (IrO₂) monolayer to optimize its electronic structure for accelerating the reaction kinetics process, in which the bonding interaction difference between Ir-H and Ir-O bonds causes an electronic reconfiguration through asymmetric orbital hybridization. The doped F elements with a lower valence state make more valence electrons revert to the Ir-5d orbitals to reduce the activation energy, leading to a higher catalytic activity. In addition, a stronger bonding interaction at Ir-F bonds also can lead to a higher structural stability. However, this advantage cannot occur at Cl-doped or Br-doped IrO₂ monolayer. This work provides a new insight into designing new-type catalysts for acidic OER.