Direct Cl─Cl Coupling Over Atomically Dispersed Ir₂ Pairs for Efficient Chlorine Electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The chlor-alkali industry relies on the chlorine evolution reaction (CER).
• Conventional dimensionally stable anodes (DSAs) have limitations in noble-metal utilization and intrinsic activity.
• Developing highly efficient and stable electrocatalysts for CER is crucial.

Purpose of the Study:

• To design and synthesize a molecularly precise dual-atom catalyst (DAC) for efficient chlorine electrosynthesis.
• To investigate the catalytic mechanism and performance of the novel catalyst.
• To assess the catalyst's durability and selectivity in practical applications.

Main Methods:

• Synthesis of atomically dispersed iridium diatomic pairs (Ir2) anchored on MnO2 nanorods (Ir2─MnO2).
• Characterization using spherical aberration-corrected microscopy and X-ray absorption spectroscopy (XAS).
• Electrochemical evaluation of CER performance, including overpotential and Tafel slope.
• Kinetic analysis, operando Raman spectroscopy, and theoretical calculations to elucidate the reaction mechanism.

Main Results:

• Successfully constructed well-defined Ir2─MnO2 DACs with validated diatomic Ir2 pairs.
• Achieved competitive CER performance with low overpotential (36.9 mV at 10 mA cm-2) and Tafel slope (34.6 mV dec-1).
• Demonstrated a direct *Cl─*Cl coupling mechanism facilitated by synergistic stabilization of intermediates on adjacent Ir-Ir dual atoms.
• Exhibited excellent durability (>500 h) and selectivity in natural seawater electrolysis.

Conclusions:

• Atomically dispersed diatomic iridium pairs on MnO2 nanorods represent a highly efficient electrocatalyst for chlorine evolution.
• Diatomic site engineering offers a powerful strategy for advancing DACs and improving electrosynthesis.
• The developed Ir2─MnO2 catalyst shows significant potential for industrial application in the chlor-alkali process and seawater electrolysis.