No abstract

Biomass‐based photothermal materials for solar steam power generation have been a recent research hotspot. However, despite the many research advances that have been made, many challenges remain. For example, high temperature carbonization leads to the loss of hydrophilicity, the surface coating is easy to peel off, hydrothermal carbonization (HTC) does not guarantee the photothermal performance, and hydrothermal carbonization fluid (HTC‐F) is difficult to handle. Herein, a new material (H‐CS/MnO2) is prepared by co‐hydrothermal carbonization of cotton stalks (CS) and MnO2, and a stable and effective evaporation system is designed. While both ensure super hydrophilicity, the stable loading of MnO2 leads to an excellent photothermal performance. Experimental results show that H‐CS/MnO2 reaches 93.46% evaporation efficiency and the evaporation rate can reach 2.43 kg m−2 h−1 under 1 sun. Moreover, by means of recycling, not only the treatment of HTC solution is solved, but also the carbon dots are continuously enriched and exhibit certain photothermal effects during the recycling process. In addition, H‐CS/MnO2 exhibited excellent salt resistance and corrosion resistance. The obtained condensate heavy ion concentration removal rate reached more than 99.9%. Therefore, the H‐CS/MnO2 fabricated herein has the possibility of practical application in the future.

In this study, a photothermal material, C-CP/MnO2, was prepared by compounding corrugated paper (CP) and MnO2, with excellent photothermal conversion efficiency. The porous structure and the presence of oxygen-containing functional groups enabled the material to have a good water transport function and a fast vapor escape rate. The special semihollow structure also allowed C-CP/MnO2 to have better thermal management and an evaporation rate that could reach 2.563 kg m–2 h–1 with an efficiency of 98.82% under 1 sun. The continuous arch structure inside C-CP/MnO2 was able to induce the Marangoni effect to achieve continuous desalination of high-concentration brine. The mirror heat collector achieved efficient light capture on the material surface through multiple reflections of light. This could increase the amount of radiation on the material surface by nearly 80%, and the evaporation rate could reach 4.314 kg m–2 h–1 under 1 sun. Moreover, this study demonstrated the light propagation path by simulating the light using Zemax to verify the correctness of the experimental results. Inspired by the sunflower chasing the sun, we designed a chasing heat collection system powered by solar panels to achieve efficient evaporation outdoors. This provided new ideas for further development of solar interface evaporation and also provided guidance for other industrial applications.