(482b) Performance of Commercial Polymer Electrolyte Membranes in Solar Fuels Devices

In the search for clean sources of energy, solar fuel devices (photoelectrochemical carbon dioxide reduction) are promising technologies for the production of renewable liquid transportation fuels. In a membrane electrode assembly type device, consisting of two electrodes separated by a hydrated polymer electrolyte membrane, the membrane must allow ion transport so that current can flow in the device, while inhibiting transport of CO₂ reduction fuel products between electrodes to minimize parasitic re-oxidation that contributes to device efficiency compromises. A prototype solar fuels device consisting of a copper gas diffusion cathode, iridium anode, and a Selemion AMV anion exchange membrane was assembled and used throughout this study. The stability of cell operation at varying potential was evaluated through cyclic voltammetry. Chronoamperometry was used to test the ability of the membrane to sustain a stable current as well as to measure the current density that the device could support. Membrane degradation was investigated by measuring the overall resistance of the prototype device using energy dispersive spectroscopy and potentio-electrochemical impedance spectroscopy before and after CO₂ reduction. Similar studies on other commercial membranes will be reported. By studying the capability of various commercial membranes to maintain a high and stable current density, further enhancement of solar fuels device operation may be achieved.