Dr Zhdanov argues that the model in our Nanoscale paper cannot prove the Au dimer as the primary species in the Ostwald ripening of Au nanoparticles on TiO 2 . We would like to point out that the relative stability of the monomer and dimer of Au has been greatly changed on the substrate compared to the gas phase. Thus, the conclusion of the original paper is solid, as proved by not only the simulations but also the further density functional theory calculations, and relevant discussions in the main text.