title: Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.
abstract: Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA, 16802 (USA).
authors.forename: Nella M
authors.initials: NM
authors.lastname: Vargas-Barbosa
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Geise
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hickner
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mallouk
mesh_terms: D004563:Electrochemistry; D004566:Electrodes; D008567:Membranes, Artificial; D055668:Photochemical Processes; D014867:Water / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D014867:Water
keywords: electrolysis; membranes; pH gradient; solar fuels; water splitting