Electrochemical cell for neutron reflectometry studies of the structure of ionic liquids at electrified interface

We describe the design and use of a closed three-electrode electrochemical cell for neutron reflectometry studies of the structure of the electrical double-layer in ionic liquids. A transparent glass counter electrode was incorporated to allow easy monitoring of any gas bubbles trapped in the cell. A 100 mm diameter silicon wafer polished to 0.1 nm rms roughness coated with gold over a chromium adhesion layer was used as the working electrode. The utility of the cell was demonstrated during neutron reflectometry measurements of the ultrahigh purity ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C(4)mpyr][NTf(2)]) at two different applied potentials.