Electroosmotic Flow in Cell Built with Electrodes Having Two Redox Couples

In an electroosmotic flow cell with two electrooxidizable and electroreducible reactants in its electrodes, the net cell reaction underlying the flow-driving proton flux from the anode to the cathode has three possible scenarios: (a) thermodynamically downhill, i.e., assisting the flow; (b) zero flow, which neither assists nor retards the flow; and (c) thermodynamically uphill, which retards the flow. A nongassing test cell was built with a ceramic membrane sandwiched between two identical electrodes comprising CeO2-x, nanoparticle-decorated, nitrogen-containing graphene oxide sheets. We demonstrated the switching between the three possible flow and current regimes as reactants were exhausted in the redox active CeO2-x, and the nitrogen-containing graphene electrodes.