Fig. 2: Structural diversity of tunnel-structured iridates.
From: Tunnel-structured IrOx unlocks catalytic efficiency in proton exchange membrane water electrolyzers
a Crystal structure of a representative tunnel-structured iridate with a 2 × 2 tunnel configuration. The inset highlights the octahedral ribbons that form the tunnel structure. b Schematic for various widths and connection models of octahedral ribbons. c Crystal structures of five tunnel-structured iridates, annotated with their chemical formulas and corresponding tunnel types. The tunnel cavities are occupied by alkali metal ions. Note: The tunnel mouths of the 1 × 2 and 1 × 2’ samples possess comparable dimensions, but with distinct structural configurations. The 2 × 2 tunnel-structured iridate corresponds to the structure shown in Fig. 2a.
