Sustainable water and energy supply have become two of the greatest global challenges of our time due to the fast-growing population and the depletion of fossil fuels.^1,2  Industrialization, water contamination, and climate change further plagues the problems of water scarcity. It is reported that over one-third of the current world population live in water-stressed areas, among which 1.2 billion people lack access to safe drinking water and 2.6 billion have inadequate sanitation.^3–5  The number of people that may be affected by water issues is projected to rise to over 3.5 billion by 2025. Though improved water conservation, maintenance of infrastructure, and novel design of catchment and distribution systems can alleviate these stresses, they can only improve the use of available fresh water rather than increase it. Desalination and water reuse are two of the few methods to increase water supply beyond the available amount from the hydrogeological cycle.⁶  Therefore, it is of great importance to explore technologies to extract fresh water from seawater or wastewater efficiently.