Chemical bias of electrochemical and photoelectrochemical water splitting using a hydrogel separator

Resorcinol-formaldehyde hydrogels are shown to be adequate separators in electrochemical and photoelectrochemical water splitting cells. Combined with concentrated buffer electrolytes, they allow the maintenance of relatively stable pH gradients between basic anolytes and acidic catholytes. The water splitting potential at a current density of 3.0mA/cm2 applied between two Pt electrodes and a pH bias of 8.1 units retained a value of 2.7V for several hours. Using iron foam/hematite as photoanode and Pt as cathode, the water splitting photocurrents at an applied potential of 1.23V reached values of 0.40 and 0.06mA/cm2 in the presence and absence, respectively, of this chemical bias.