An amorphous lanthanum–iridium solid solution with an open structure for efficient water splitting

Abstract

The lanthanum–iridium amorphous metal oxides with a novel flute-like nanostructure (La–Ir NF) were synthesized from the perspective of controlling the material's nanoscale morphology and crystal structure. The iridium mass ratio of the prepared La–Ir NF was only 38.8% (wt%), and it shows outstanding OER activity with a lower onset potential and Tafel slope, as well as a 12-fold higher mass activity than that of crystalline IrO₂ oxides. Physical and chemical structural characterization experiments reveal that the amorphous La–Ir NF with a shorter atomic distance and the presence of La ions result in a lower symmetry of the IrO₆ octahedron. The flute-like open structure increases the utilization efficiency of Ir atoms and the 5d orbital electron reconfiguration in the distorted IrO₆ coordination is responsible for the excellent OER activity of the La–Ir NF. Our present study suggests that the amorphous open-structure morphology strategy is a promising way to prepare more efficient electrocatalysts, which can probably be applied to other transition metal oxides.