LAUSR

Realizing efficacious π-donation from the O 2p orbital to electron-deficient metal (t2g ) d-orbitals along with separately tuned adsorption of *O and *OOH, is an imperious pre-requisite for an electrocatalyst design to demonstrate boosted oxygen evolution reaction (OER) performance. To regulate the π-donation and the adsorption ability for *O and *OOH, herein, a facile strategy to modulate the electron transfer from electron-rich t2g -orbitals to electron-deficient t2g -orbitals, via strong π-donation from the π-symmetry lone pairs of the bridging O2- , and the d-band center of a biomimetic honeycomb (BHC)-like nanoarchitecture (Ir1- x (Ir0.8 V0.2 O2 )x -BHC) is introduced. The suitable integration of V heteroatoms in the single crystal system of IrO2 decreases the electron density on the neighboring Ir sites, and causes an upshift in the d-band center of Ir1- x (Ir0.8 V0.2 O2 )x -BHC, weakening the adsorption of *O while strengthening that of *OOH, lowers the energy barrier for OER. Therefore, BHC design demonstrates excellent OER performance (shows a small overpotential of 238 mV at 10 mA cm-2 and a Tafel slope of 39.87 mV dec-1 ) with remarkable stability (130 h) in corrosive acidic electrolyte. This work opens a new corridor to design robust biomimetic nanoarchitectures of modulated π-symmetry (t2g ) d-orbitals and the band structure, to achieve excellent activity and durability in acidic environment.