Salinity Gradient Power Driven Water Electrolysis for Hydrogen Production

Abstract

The present work demonstrates an innovative system combining Reverse Electrodialysis (RED) and Alkaline Polymer Electrolyte Water Electrolysis (APEWE) for sustainable hydrogen production. The Salinity Gradient Power (SGP)-RED unit was tested with a thermally regenerative solution of NH₄HCO₃ in the concentration range of 0.15-1.5 M, whereas the water electrolysis unit equipped with quaternary ammonium functionalized anion selective membrane, Ni anode modified with Platinum Group Metal (PGM)-free electrocatalyst, Ni cathode modified with an electrochemically Reduced Graphene Oxide (RGO) was investigated at a varying temperature (50 - 80 °C). The integrated RED-APEWE system reached a maximum hydrogen production rate of 3.0x10^-3 mol H₂/h per cm² of electrode surface area. Owing to the use of the thermally regenerative NH₄HCO₃ solution, this work presents a profound basis to design a system allowing the conversion of low-grade waste heat into electricity in a closed loop with simultaneous production of hydrogen using salinity gradient energy.