Carbonized rice husk foam constructed by surfactant foaming method for solar steam generation

Solar steam generation is a promising way for the harvesting and conversion of solar illumination. Heat localization systems have opened a new route to enhance the solar steam efficiency with localizing the absorbed solar energy and minimizing the heat losses. Many carbon-based, organic and plasmonic absorbers have been developed to achieve high-efficiency vapor evaporation in the past years. To provide a low cost and operability strategy, the carbonized rice husk, a biogenic carbon, is first used to construct a three-dimensional (3D) foam absorber in this paper. By employing surfactant foaming method, many micron pore channels are formed to ensure convenient water transfer. Meanwhile, due to the multiple internal reflections of light-rays in these cross pores, the light absorption can be enhanced up to ∼92%. Under a solar intensity of 1 kW m−2, the foam absorber achieves a solar steam conversion efficiency at ∼71%. This work not only represents an original exploration concerning with carbonized rice husk absorber, but also provides a possible strategy for the exploitation of other powdery solar-thermal agents in this field.