Solar vapor generation is a renewable and hopeful technology for obtaining freshwater from underground water, dyeing wastewater, and seawater. Herein, hierarchical MnO2 nanosheets grown on cotton fabric (Mn-CF) have been developed for solar-driven water evaporation. Black MnO2 nanosheets and nanoflowers are in situ chemically deposited on cotton fabric (CF), which leads to a solar absorption ability as high as 95% from 300 to 2500 nm. Due to the synergistic effect of the super-hydrophilic CF and hierarchical MnO2 nanosheets, Mn-CF results in a water evaporation rate of 1.40 kg m–2 h–1 with the photothermal conversion efficiency of 87.48% under 1 sun illumination (1 kW m–2). During the desalination test, Mn-CF can be renewed by washing off the steamed salts through a simple ultrasonication or hand-washing. Moreover, Mn-CF remains stable after 40 cycles, each lasting 1 h under 1 sun irradiation. A Mn-CF-based solar steam generator (Mn-CF-SSG) enables to effectively purifying simulated dyeing wastewater and seawater using natural sunlight. The cost of preparing 1 m2 Mn-CF is about $1.5. This work provides a simple method to prepare flexible and washable Mn-CF-SSG with low-cost and high efficiency that has huge potential for practical application of seawater desalination.

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Nowadays, freshwater shortage, energy crisis and environmental pollution are the three major threats to human beings. Herein, we develop a photothermal material based on bagasse for solar steam generation to relieve freshwater crisis and mitigate environmental pollution caused by bio-waste. The mainly functional part of the solar driven steam generator in this paper is bagasse-based photothermal aerogel (B-PTA), which composes of carbonized bagasse (CB) and bagasse-derived cellulose ber (BDCF). The B-PTA with CB can effectively absorb solar (~95%) and has an excellent light-to-heat ability. The B-PTA with DBCF has super-hydrophilicity, water transport and retention ability. Depending on the excellent light absorption and 3D water passageway, the B-PTA gives a water evaporation rate of 1.36 kg m -2 h -1 , and can achieve a photothermal conversion e ciency of 77.34% under 1-sun illumination (1 kW m -2 ). The B-PTA has excellent stability that the e ciency without signi cant decrease after 20 cycles. In addition, the B-PTA can effectively desalt seawater and purify dye wastewater with natural sunlight. Therefore, turning bio-waste into valuable photothermal material for solar steam generation is possible. Due to the merits of low cost, scalability, environmental friendliness, B-PTA has the potential for real-world water puri cation.

Nowadays, freshwater shortage, energy crisis and environmental pollution are the three major threats to human beings. Herein, we develop a photothermal material based on bagasse for solar steam generation to relieve freshwater crisis and mitigate environmental pollution caused by bio-waste. The mainly functional part of the solar driven steam generator in this paper is bagasse-based photothermal aerogel (B-PTA), which composes of carbonized bagasse (CB) and bagasse-derived cellulose fiber (BDCF). The B-PTA with CB can effectively absorb solar (~95%) and has an excellent light-to-heat ability. The B-PTA with DBCF has super-hydrophilicity, water transport and retention ability. Depending on the excellent light absorption and 3D water passageway, the B-PTA gives a water evaporation rate of 1.36 kg m–2 h–1, and can achieve a photothermal conversion efficiency of 77.34% under 1-sun illumination (1 kW m–2). The B-PTA has excellent stability that the efficiency without significant decrease after 20 cycles. In addition, the B-PTA can effectively desalt seawater and purify dye wastewater with natural sunlight. Therefore, turning bio-waste into valuable photothermal material for solar steam generation is possible. Due to the merits of low cost, scalability, environmental friendliness, B-PTA has the potential for real-world water purification.