To determine the potential window for As deposition, we assess the electrochemical processes occurring at the In-electrolyte interface by comparing the current-voltage response in cyclic voltammetry (CV) for electrolytes with and without As precursor (Figure ). The vertical dashed lines in Figure correspond to estimated redox thermodynamic potentials of some expected reactions (for detailed calculation of the potential values see supplementary information S2). All potentials in this manuscript are referenced to Ag/AgCl. The cathodic sweeps in Figure clearly show a reduction peak at ~ -1.22 V (followed by two smaller peaks) for both electrolytes. These features are in good agreement with the reduction of In 2 O 3 to In. At more cathodic potentials the current exponentially increases, with the absolute current density being higher for the electrolyte containing As ions. We attribute this fast increase in current to the H 2 evolution reaction (V H2O/H2 = -0.957 V). The additional current for the As-containing electrolyte is likely due to the reduction of As 3+ into As solid (V As3+/As = -0.938 V):