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

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Conductive bifunctional covalent organic frameworks (COFs) are crucial for overall water splitting but face challenges due to limited multifunctional active sites.
• Developing efficient electrocatalysts with robust bifunctional activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for alkaline water electrolysis.

Purpose of the Study:

• To design and synthesize a novel pyrolysis-free electrocatalyst based on redox-active COFs.
• To anchor atomically dispersed iridium-ruthenium dual-active sites onto a donor-acceptor-based COF (Ace and TAPT, IrRu DAS/AT-COF).
• To investigate the catalytic performance and mechanism for alkaline water electrolysis.

Main Methods:

• Synthesis of IrRu DAS/AT-COF by anchoring atomically dispersed iridium-ruthenium dual-active sites onto a donor-acceptor-based redox-active COF.
• Electrocatalytic testing in 1 m KOH for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).
• Utilizing operando spectroscopy and theoretical calculations to elucidate the catalytic mechanism and active site interactions.

Main Results:

• The synthesized IrRu DAS/AT-COF exhibited robust bifunctional activities and stability for HER and OER in 1 m KOH.
• Performance surpassed existing benchmarks and most noble-metal-based catalysts.
• Operando spectroscopy and theoretical calculations revealed a multi-site separation mechanism and a giant multifunctional active-site synergistic enhancement (MASE) effect.

Conclusions:

• The MASE effect, triggered by intramolecular electronic modulations between Ir and Ru sites, balances and accelerates elementary steps in water electrolysis.
• The catalyst demonstrated improved conductivity, enhanced H2O adsorption, decreased H2O dissociation energy barrier, and optimal adsorption of H/O intermediates.
• This work offers new insights into designing multi-site catalytic environments in bifunctional COFs for advanced water electrolysis electrocatalysts.