Fig. 2: The concept of direct air electrolysis (DAE) for hydrogen production.
a A schematic diagram of the DAE module with a water harvesting unit made of porous medium soaked with the hygroscopic ionic solution. b A schematic diagram of the cross-section of the DAE module, showing the electrodes are isolated from the air feed, and the absorbed water are transported to the electrode by capillaries of the sponge. c Equilibrium water uptakes of hygroscopic solutions at different air R.H.31,32. d J–V curves for DAE modules using Pt or Ni electrodes sandwiched with KOH electrolyte (in equilibrium with 15% and 60% R.H. at 20 °C) soaked in a melamine sponge. e Effect of sponge materials on J-V performance of DAE modules using H2SO4 electrolyte in equilibrium with 30% R.H. at 25 °C. The inset shows the optical micro image for the glass foam. Source data are provided as a Source Data file.
