Atmospheric water capture (AWC) is an alternative method of localized water production whereby water vapor is removed from air to produce drinking water. The most advantageous AWC applications are for developing solar energy driven, off-grid water sources. Solid phase silica gel (SiO₂) desiccant materials can adsorb and concentrate water vapor in many relative humidity (RH) (20–100%) and temperature (20–40 °C) conditions. Generating sufficient solar thermal heat to release all of the sorbed water vapor from the desiccant bed can take many hours of sunlight, which limits the AWC system to just one adsorption–desorption–condensation cycle per day. In this work, we applied solar-light active photothermal nanomaterials (gold cubes and rods, carbon black) on SiO₂ desiccant surfaces with the aim of providing localized heat sources, thereby rapidly increasing desiccant surface temperature, improving kinetics and totality of water vapor desorption, and allowing additional AWC cycles per day. Desiccants were tested for adsorption at 40%, 60%, and 80% RH and desorption under 1-Sun simulated solar irradiation. In the optimal use-case scenario, 5 wt% carbon black coated SiO₂ could cycle through >10 adsorption–desorption phases per day to produce 0.47 g H₂O per g desiccant/12 hours (2 L m⁻²) at 40% RH. By innovating material and AWC system design to operate over multiple atmospheric water harvesting cycles per day, we showed that nano-enabled photothermal desiccants can be applied in semi-arid climates to produce 10-fold more water than one standard cycle using a bare SiO₂ desiccant.

中文翻译：

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纳米光热干燥剂增强了阳光驱动的大气水捕集能力

大气水捕集（AWC）是一种局部生产水的替代方法，通过该方法可以从空气中去除水蒸气以产生饮用水。AWC最有利的应用是开发太阳能驱动的离网水源。固相硅胶（SiO ₂）干燥剂材料可以在许多相对湿度（RH）（20–100％）和温度（20–40°C）的条件下吸附和浓缩水蒸气。产生足够的太阳热能从干燥剂床中释放出所有吸附的水蒸气会花费很多小时的阳光，这将AWC系统限制为每天只有一个吸附-解吸-冷凝循环。在这项工作中，我们在SiO ₂上应用了日光活性光热纳米材料（金块和棒，炭黑）旨在提供局部热源的干燥剂表面，从而迅速提高干燥剂表面温度，改善动力学和水蒸气解吸的总体能力，并允许每天进行额外的AWC循环。测试干燥剂在40％，60％和80％RH下的吸附以及在1-Sun模拟太阳辐射下的解吸。在最佳用例场景中，每天使用5 wt％的炭黑涂覆的SiO ₂可以循环经过10个以上的吸附-解吸阶段，每12小时产生0.47 g H ₂ O / g干燥剂（2 L m ^-2）在40％RH下。通过创新材料和AWC系统设计以每天在多个大气水收集循环中运行，我们证明了纳米功能的光热干燥剂可在半干旱气候下使用，比使用裸露的SiO ₂产生的标准循环多出10倍的水。干燥剂。