Effect of lattice strain on the electro-catalytic activity of IrO2 for water splitting.

The lattice strain of IrO2 plays a critical role in determining its OER activity. The Ir-O bond length change in IrO6 coordination induces lattice strain. Increasing the annealing temperature results in a stretching strain along the c axis and a compressive strain on the a and b axes, leading to a larger c/a ratio. Enhancing the lattice strain decreases the c/a ratio, which is beneficial for improving OER activity.