Solar steam generation is an environmentally friendly water treatment method that produces clean water using solar energy. However, it is still a challenge to effectively prevent the performance deterioration when most photothermal conversion materials are used to evaporate high‐concentration salt‐containing wastewater or strong acid/alkali solution. Herein, a stable and effective solar evaporator is designed using natural sugarcane, where sucrose is simply dehydrated into carbon particles by hydrothermal reaction in sulfuric acid. With a honeycomb structure, it not only enables water transport capacity but also promotes sunlight absorption. Sulfuric acid hydrothermal carbonized sugarcane (SHCSC) can reach up to 95.36% solar absorption in a wide wavelength range (200–2500 nm) and a high evaporation rate of 2.32 kg m−2 h−1 under 1 sun illumination. More importantly, SHCSC has an excellent adsorption capacity with ion removal rate of 99.9% even under artificial wastewater containing 1000 mg L−1 of mixed metal ions. SHCSC also can perform efficiently and stably at a high evaporation rate above 2.2 kg m−2 h−1 in strong acidic or alkaline wastewater. These findings suggest that SHCSC can be potentially applied to the efficient harvest of clean water from the high‐concentration wastewater containing acid, alkali, and mixed metal ions.

As a new type of solar energy utilization, solar photothermal water evaporation system has the characteristics of high photothermal conversion efficiency and green environmental protection, which can be widely used in the field of seawater desalination and sewage treatment. The bagasse carbonized by high-temperature pyrolysis was used as the photo-absorption material, and the polyurethane sponge-based aerogel photo-thermal conversion material was prepared with the double-network composite aerogel constructed by chitosan and polyurethane sponge as the substrate. It has good evaporation stability and is suitable for portable evaporation equipment. Moreover, when the carbonization temperature of carbonized bagasse was 500 °C and the addition amount was 1%, the evaporation performance of aerogel was the best. In the wavelength range of 200~2500 nm, its absorption rate can reach 98.2%, and its evaporation rate can reach 2.04 kg m−2h−1 at 1 kW m−2. In addition, the aerosol has good stability in general seawater and alkaline sewage, and is an effective method for solving seawater and sewage.