Solar vapor generation (SVG) as an emerging technology recently shows great promise as a low-cost solution to safe water challenges in economically disadvantaged and deindustrialized communities, and communities burdened with legacy-contamination. It uses nanophotonic materials to convert solar energy to heat to vaporize water, as an efficient water-purifying and desalinization technology. Efficient SVG relies on high solar power density. In reality, however, the sunlight illuminates on earth surface in oblique angles, which causes significant drop of receiving solar power density and thus the SVG water production. To recover the oblique-incidence-induced energy loss, living plants have developed phototropism to spontaneously sense and track light source by self-orienting their surfaces to constantly face to the sun moving cross the sky daily and seasonally, which effectively raises their photo-thermal energy production. In contrast, no man-made material system can omnidirectionally track and harvest the input emissive energy fully autonomously. Here we present a first-of-a-kind artificial phototropic solar vapor generator (APSVG), based on omnidirectional light tracking hydrogel, which can real-time and precisely track the light from all directions in entire 3D space and thus effectively maintain the highest water production. At normal incidence (0o), the APSVG generates 3kg purified water from a reservoir of 1 m2 surface area with 70% (1 sun) and 80% (2 sun) efficiency. At oblique incidence of as high as 75o angle, the vapor production successfully maintains at 90% of the production under normal incidence, corresponding to &gt;400% oblique-loss compensation. Such a smart water-vapor generator can operate under various ambient temperatures and light sources, using many existing responsive photonic materials. This provides a high-energy-efficiency, low-cost solution to drinking water insecurity and inequality.

Enhanced purified water production by artificial phototropic solar vapor generator based on nanophotonic hydrogel

256th National Meeting (2018)

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