Engineering Iridium-Ruthenium Dual-Atomic Active Sites on Redox-Active Covalent Organic Frameworks for Boosted...

The achievement of conductive bifunctional covalent organic frameworks (COFs) for overall water splitting remains challenging due to the lack of multifunctional active sites. Herein, the atomically dispersed electroactive iridium-ruthenium dual-active sites are anchored on donor-acceptor-based redox-active COF (Ace and TAPT, IrRu DAS/AT-COF) as a pyrolysis-free electrocatalyst for alkaline water electrolysis application. The as-synthesized IrRu DAS/AT-COF exhibits robust bifunctional activities and stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 m KOH, surpassing the benchmarks and most recent noble-metal-based catalysts. Operando spectroscopy and theoretical calculations unveil the multiple active sites separation mechanism on IrRu DAS/AT-COF, where the giant multifunctional active-site synergistic enhancement (MASE) effect was triggered by the intramolecular compensating electronic modulations between the Ir_SA and Ru_SA sites. This setting can balance the competitive effects of the following elementary steps and simultaneously accelerate them into the local environment of catalytic units, including (i) the improved conductivity and H₂O adsorption, (ii) decreased H₂O dissociation energy barrier, (iii) optimal adsorption of H/O intermediates. This work provides new insights into the design of multi-site catalytic local environments in bifunctional COFs electrocatalysts for water electrolysis.