Smart coating materials of buildings for atmospheric water harvesting and response

The promising atmospheric water harvesting technology has been the focus of much attention for the challenge of alleviating global water scarcity. Here, we report a smart coating material for buildings, in short, super hygroscopic material (SHM) modified calcium silicate hydrate (CSH) by using a three-dimensional gel as support, for the first time. The obtained coating material achieves not only ultra-high humidity capture capacities (over 463 mg/g of its weight under room temperature with a relative humidity of 98%) but also rapid and obvious color variations as a response to humidity capture that is visible to the naked eye. More importantly, the above-mentioned phenomenon can be repeated over a wide temperature (4-40 °C) and humidity (43 - 98 %) range, suggesting that the present coating material has a promising potential to be applied in the real-world humidity capture and response of buildings.