Catalyst‐Support Interactions in Zr₂ON₂‐Supported IrO_x Electrocatalysts to Break the Trade‐Off Relationship Between the Activity and Stability in the Acidic Oxygen Evolution Reaction

Abstract

The development of highly active and durable Ir‐based electrocatalysts for the acidic oxygen evolution reaction (OER) is challenging because of the corrosive anodic conditions. Herein, IrOx/Zr2ON2 electrocatalyst is demonstrated, employing Zr2ON2 as a support material, to overcome the trade‐off between the activity and stability in the OER. Zr2ON2 is selected due to its excellent electrical conductivity and chemical stability, and the fact that it induces strong interactions with IrOx catalysts. As a result, IrOx/Zr2ON2 electrocatalysts exhibit outstanding OER performances, reaching an overpotential of 255 mV at 10 mA cm−2 and a mass activity of 849 mA mgIr−1 at 1.55 V (vs the reversible hydrogen electrode). The activity of IrOx/Zr2ON2 is maintained at 10 mA cm−2 for 5 h, while in contrast, IrOx/ZrN and an unsupported IrOx catalyst undergo drastic degradation. Combined experimental X‐ray analyses and theoretical interpretations reveal that the reduced oxidation state of Ir and the extended IrO bond distance in IrOx/Zr2ON2 effectively increase the activity and stability of IrOx by altering reaction pathway from a conventional adsorbate evolution mechanism to a lattice oxygen‐participating mechanism. These results demonstrate that it is possible to effectively reduce the Ir content in OER catalysts through interface engineering without sacrificing the catalytic performance.

Design Strategies of Active and Stable Oxygen Evolution Catalysts for Proton Exchange Membrane Water Electrolysis

“…82 Additionally, the promotional role of strain on OER activity was reported for the IrO x catalyst on the Zr 2 ON 2 support (IrO x /Zr 2 ON 2 ). 83 This catalyst exhibited a 4.4% tensile-strained surface compared to that of the pure IrO 2 surface (Figure 5h,i). They suggested that the enhancement in the OER activity of the IrO x /Zr 2 ON 2 catalyst was predominantly induced by the reduced oxidation state of Ir due to the tensile strain effect (Figure 5j,k).…”

“…This impact of lattice strain on the OER activity has been widely investigated in forms of thin film and nanoparticle catalysts. − Jiang et al identified the beneficial role of strain in improving OER activity by generating stacking faults in Ru nanoparticles, which exhibited a lower η 10 value of 196 mV compared to the approximately 310 mV of RuO 2 (Figure d–g) . Additionally, the promotional role of strain on OER activity was reported for the IrO x catalyst on the Zr 2 ON 2 support (IrO x /Zr 2 ON 2 ) . This catalyst exhibited a 4.4% tensile-strained surface compared to that of the pure IrO 2 surface (Figure h,i).…”

“…(h) Schematic representation of the lattice and possible charge transfer, (i) Fourier-transformed extended X-ray absorption fine structure (EXAFS) ( R -space with k -weight 3) analysis, (j) free energy diagrams via DFT calculation, and (k) polarization curves for the IrO x catalyst on the Zr 2 ON 2 support. (h–k) Reprinted with permission from ref . Copyright 2023 Wiley-VCH.…”

Acid-Treated RuO2/Co3O4 Nanostructures for Acidic Oxygen Evolution Reaction Electrocatalysis

“…It was reported that the IrO x /Zr 2 ON 2 electrocatalyst exhibits excellent activity and stability in acidic OER. 28 However, the mechanism behind interfacial engineering to promote catalytic reactions by loading active substances on support materials requires further investigation.…”

“…Kim et al, on the other hand, compared a different support material, such as Zr 2 ON 2 , which has good electrical conductivity, chemical stability, and strong interaction with IrO x catalysts. It was reported that the IrO x /Zr 2 ON 2 electrocatalyst exhibits excellent activity and stability in acidic OER . However, the mechanism behind interfacial engineering to promote catalytic reactions by loading active substances on support materials requires further investigation.…”