1 Supporting Information Evidence for Charge Transfer at the Interface between Hybrid Phosphomolybdate and Epitaxial Graphene. L. Huder, C. Rinfray, D. Rouchon, A. Benayad, M. Baraket, G. Izzet, F. Lipp-Bregolin, G. Lapertot, L. Dubois, A. Proust, A. G. M. Jansen, F. Duclairoir* *e-mail: Florence.duclairoir@cea.fr Table of Content: 1- Description of analytical methods p 2 2- Cell used for localized functionalization p 3 3- Secondary electron X-ray image of the functionalized zone p 4 4- Comparison with reference compound K Mo Sn [I] p 6 5- POM surface coverage determination p 7 6- References p 7