1. Atomic-Layer IrOxEnabling Ligand Effect Boosts Water Oxidation Electrocatalysis
- Author
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Luo, Heng, Lin, Fangxu, Zhang, Qinghua, Wang, Dawei, Wang, Kai, Gu, Lin, Luo, Mingchuan, Lv, Fan, and Guo, Shaojun
- Abstract
An in situformed IrOx(x≤ 2) layer driven by anodic bias serves as the essential active site of Ir-based materials for oxygen evolution reaction (OER) electrocatalysis. Once being confined to atomic thickness, such an IrOxlayer possesses both a favorable ligand effect and maximized active Ir sites with a lower O-coordination number. However, limited by a poor understanding of surface reconstruction dynamics, obtaining atomic layers of IrOxremains experimentally challenging. Herein, we report an idea of material design using intermetallic IrVMn nanoparticles to induce in situformation of an ultrathin IrOxlayer (O-IrVMn/IrOx) to enable the ligand effect for achieving superior OER electrocatalysis. Theoretical calculations predict that a strong electronic interaction originating from an orderly atomic arrangement can effectively hamper the excessive leaching of transition metals, minimizing vacancies for oxygen coordination. Linear X-ray absorption near edge spectra analysis, extended X-ray absorption fine structure fitting outcomes, and X-ray photoelectron spectroscopy collectively confirm that Ir is present in lower oxidation states in O-IrVMn/IrOxdue to the presence of unsaturated O-coordination. Consequently, the O-IrVMn/IrOxdelivers excellent acidic OER performances with an overpotential of only 279 mV at 10 mA cm–2and a high mass activity of 2.3 A mg–1at 1.53 V (vs RHE), exceeding most Ir-based catalysts reported. Moreover, O-IrVMn/IrOxalso showed excellent catalytic stability with only 0.05 at. % Ir dissolution under electrochemical oxidation, much lower than that of disordered D-IrVMn/IrOx(0.20 at. %). Density functional theory calculations unravel that the intensified ligand effect optimizes the adsorption energies of multiple intermediates involved in the OER and stabilizes the as-formed catalytic IrOxlayer.
- Published
- 2024
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