Fig. 4. Water harvesting performance of the water harvester by applying the batch-processed alternating mode.

a Schematic diagram of the proposed batch-processed alternating mode, showing the variation of water capture, release, and production in a single diurnal cycle. The eight pieces of sorbents are simultaneously exposed to the high RH ambient during the night, and consequent batch-operation desorption releases water vapor with freshwater production during the daytime. The white, blue, red, and yellow lines represent RH variation, water uptake, water release, and water production over the whole day, respectively. b Air temperature and RH variation within 24 h in the semi-arid region of Lanzhou, China. RH: relative humidity; c Temperature variations of the sorbent and device during eight desorption cycles including the heating stages and standby stages. d Mass of desorbed and collected water during each cycle, and its accumulated water. e Energy consumption during each desorption cycle. f Detected concentrations of the possible metal and ions in the collected water. All error bars represent SD.