An adaptive solar evaporator constructed by corn straw derived sponge and konjac glucomannan-based water management platform

Abstract

The technology of interfacial solar vapor generation (ISVG) presents a highly promising avenue for enhancing the efficiency of water purification processes. However, managing the uncontrollable water content in evaporators remains a challenge, hindering the maintenance of stable and efficient ISVG performance in real-world scenarios. To address this issue, we have developed an adaptive-mode solar evaporator (SPPU-CKGM), which comprises a cellulose/konjac glucomannan composite hydrogel (CKGM) and a corn straw-derived photothermal polyurethane sponge (SPPU). The innovative device, featuring a bi-layer structure, is capable of adaptively selecting the optimal operational mode in response to the varying water content it contains. When the content is high, SPPU-CKGM increases the evaporation rate to reduce the water content. Conversely, when the water content is low, it maintains a high evaporation rate of ca. 2.35 kg/m 2 /h. In outdoor experiments, the water purification device assembled with SPPU-CKGM achieved a freshwater yield of 6.5 kg/m 2 /day. This work introduces a novel method for designing an adaptive device that excels in achieving efficient freshwater production in practical conditions. • A crop-derived solar evaporator was designed through a green and simple method. • The device could automatically switch working modes based on water content. • Evaporation rate reached 2.35 kg/m 2 /h under 1 sun illumination.