The surface of In2O3 (Ia-3) [206] was prepared from an optimised bulk structure (10.41 Å Literature: 10.18 Å ) using the Atomic Simulation Environment (ASE). An 8 x 8 x 4 In atoms supercell of In2O3 (111) was constructed, and the bottom two layers were fixed upon optimisation. All surfaces were optimised using a vacuum layer of > 15 Å. For the optimisation of the adsorbate, the vacuum was applied above the height of the adsorbate.