Self-Assembly of Ir-Based Nanosheets with Ordered Interlayer Space for Enhanced Electrocatalytic Water Oxidation

Iridium (Ir)-based electrocatalysts are widely explored as benchmarks for acidic oxygen evolution reactions (OERs). However, further enhancing their catalytic activity remains challenging due to the difficulty in identifying active species and unfavorable architectures. In this work, we synthesized ultrathin Ir-IrOx/C nanosheets with ordered interlayer space for enhanced OER by a nanoconfined self-assembly strategy, employing block copolymer formed stable end-merged lamellar micelles. The interlayer distance of the prepared Ir-IrOx/C nanosheets was well controlled at similar to 20 nm and Ir-IrOx nanoparticles (similar to 2 nm) were uniformly distributed within the nanosheets. Importantly, the fabricated Ir-IrOx/C electrocatalysts display one of the lowest overpotential (eta) of 198 mV at 10 mA cm(geo)(-2) during OER in an acid medium, benefiting from their features of mixed-valence states, rich electrophilic oxygen species (O(II-delta)-), and favorable mesostructured architectures. Both experimental and computational results reveal that the mixed valence and O(II-delta)- moieties of the 2D mesoporous Ir-IrOx/C catalysts with a shortened Ir-O(II-delta)- bond (1.91 angstrom) is the key active species for the enhancement of OER by balancing the adsorption free energy of oxygen-containing intermediates. This strategy thus opens an avenue for designing high performance 2D ordered mesoporous electrocatalysts through a nanoconfined self-assembly strategy for water oxidation and beyond.

Automated summary

In this work, ultrathin Ir-IrOx/C nanosheets with ordered interlayer space were synthesized through a nanoconfined self-assembly strategy, exhibiting enhanced catalytic activity for acidic oxygen evolution reactions. The nanosheets showed one of the lowest overpotential during OER in an acid medium, benefiting from their mixed-valence states, rich electrophilic oxygen species, and favorable mesostructured architectures. This study opens a new avenue for designing high-performance 2D ordered mesoporous electrocatalysts for water oxidation and beyond through a nanoconfined self-assembly strategy.