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Self-floating hybrid hydrogels assembled with conducting polymer hollow spheres and silica aerogel microparticles for solar steam generation
- Tan, Mengyao, Wang, Jin, Song, Wenhui, Fang, Jianhui, Zhang, Xuetong
- Journal of materials chemistry A 2019 v.7 no.3 pp. 1244-1251
- absorption, aerogels, contact angle, cost effectiveness, energy conversion, evaporation, freezing, freshwater, gelation, heat, hydrogels, hydrophilicity, hydrophobicity, lighting, microparticles, polyvinyl alcohol, seawater, silica, solar energy, steam, thermal conductivity, water pollution, water supply, xerogels
- The design and synthesis of solar steam generation materials have received considerable attention due to their capacity to produce freshwater from seawater or contaminated water by a straightforward utilisation of solar energy. The practical application of these materials, however, is restricted by their low evaporation efficiency and non-durable floating capacity on water. Herein, flexible and self-floating polyvinyl alcohol (PVA) based hybrid hydrogels for solar steam generation are designed and synthesized by assembling two types of functional particles within the network: conducting polymer hollow spheres (CPHSs) for achieving solar absorption and heat conversion, and silica aerogel microparticles for density reduction and efficient energy conversion confined to a small amount of surrounding water. Following a freezing process, functionalized hybrid hydrogels with macro-sized channels are generated, contributing to rapid water supply. The Janus surface nature, with one side being hydrophilic (contact angle ca. 60°) and another hydrophobic (contact angle up to 135°), of the hybrid hydrogel was found due to the formation of a gradient distribution of silica aerogel particles via controlling the gelation conditions. Consequently, the density of the hybrid hydrogels is controlled in the range of 0.8–1.0 g cm⁻³ and the thermal conductivity of the corresponding xerogels in the range of 0.030–0.035 W m⁻¹ K⁻¹, depending on the content of the silica aerogels. High water production of the hybrid hydrogel at a rate of 1.83 kg m⁻² h⁻¹ under 1 sun illumination has been demonstrated, which is an important step towards a cost-effective solution for the scarcity of clean water.