In addition to the surface models that result from the adsorption of a single TiCl4 molecule, in order to investigate the double reaction phenomenon of EG and GL, we have also built models in which two The overall energy change for the reactions between the TiCl3/TiCl2 terminated anatase TiO2 and rutile TiO2 surfaces with EG and GL is presented in table 2 and these results show that the calculated energies for the reactions between the TiCl3 terminated surfaces with EG and GL, associated with the release of one HCl molecule, are exothermic and therefore favourable. There are also clear differences when EG and GL bind with TiCl3 and TiCl2 terminated TiO2 surfaces. The calculated energies for the reactions between the TiCl2 terminated surfaces with EG and GL, associated with the release of one HCl molecule, are endothermic, meaning that these reactions are not favourable. We found a similar difference for the reaction of TiCl3/TiCl2 with aromatic precursors . We also consider the Ti-O distances formed between the EG and GL with TiCl3/TiCl2 species as well as changes in the Ti-surface distances between TiCl3 and TiCl2 and surface oxygens after the introduction of EG and GL, table SI 2. We notice that Ti-O bonds formed between EG and GL and the From table we see that the EG and GL molecules interact favourably in an upright configuration at the 2TiCl3 terminated anatase TiO2 surface. However, there is a further gain in energy of -0.55 eV for EG and -0.33 eV for GL when the molecules change their configuration from upright to flat lying, and a second HCl molecule is released. These energies show that EG and GL could also undergo double reactions on the anatase TiO2 surface, although for GL this difference in energy is smaller than for EG.