1 Surface Reactivity from Electrochemical Lithography: Illustration in the Steady- State Reductive Etching of Perfluorinated Surfaces. Hassan Hazimeh, Sandra Nunige, Renaud Cornut, Christine Lefrou, Catherine Combellas, Frédéric Kanoufi Supporting Information Experimental Section Materials Glass substrates were 1.1 mm thick microscope slides, Si/SiO 2 substrates were 1x1 cm 2 plaques (from 2 inches wafers, ACS). ITO was provided by Saint-Gobain Recherche (Aubervilliers, France). Glass substrates were cleaned with a freshly prepared piranha solution (70:30 v/v, concentrated H 2 SO 4 /aqueous H 2 O 2 (35%)) at 150 °C for 30 min. ITO was cleaned in an alkaline piranha solution (5:1:1 v/v/v, H 2 O:H 2 O 2 (30%):NH 4 OH (25%)) at 70°C for 1 h. The substrates were then rinsed with pure water (Millipore, resistivity ≥ 18.2 MΩ cm), cleaned by ultrasonication in water for 1 min, and dried under nitrogen. Silanization was conducted in the same way for the three kinds of substrates in order to give the fluorinated SAMs: in the gas phase, the substrates were placed in a sealed cell in the presence of an open flask of 1H,1H,2H,2H-perfluorodecyltrichlorosilane (CF 3 (CF 2 ) 7 (CH 2 ) 2 SiCl 3 , 97%), heated at 110 °C for 2 h. All chemicals were from Aldrich and used as received. Electrochemical characterizations. Cyclic voltammetric experiments were performed with a classical three-electrode setup with a 250 μm diameter Pt wire counter-electrode and a 250 μm Ag/AgCl wire (pseudo-reference). SECM