Magnetically induced convection enhances water electrolysis in microgravity.

Since the early days of space exploration, the efficient production of oxygen and hydrogen via water electrolysis has been a central task for regenerative life-support systems. Water electrolysers are, however, challenged by the near-absence of buoyancy in microgravity, resulting in hindered gas bubble detachment from electrodes and diminished electrolysis efficiencies. Here we show that a commercial neodymium magnet enhances water electrolysis with current density improvements of up to 240% in microgravity by exploiting the magnetic polarization of the electrolyte and the magnetohydrodynamic force. We demonstrate that these interactions enhance gas bubble detachment and displacement through magnetic convection and achieve passive gas-liquid phase separation. Two model magnetoelectrolytic cells, a proton-exchange membrane electrolyser and a magnetohydrodynamic drive, were designed to leverage these forces and produce oxygen and hydrogen at near-terrestrial efficiencies in microgravity. Overall, this work highlights achievable, lightweight, low-maintenance and energy-efficient phase separation and electrolyser technologies to support future human spaceflight architectures.