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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.

Abstract. In this paper, we investigate the complex dynamics of a spatial plankton-fish system with Holling type III functional responses. We have carried out the analytical study for both one and two dimensional system in details and found out a condition for diffusive instability of a locally stable equilibrium. Furthermore, we present a theoretical analysis of processes of pattern formation that involves organism distribution and their interaction of spatially distributed population with local diffusion. The results of numerical simulations reveal that, on increasing the value of the fish predation rates, the sequences spots → spot-stripe mixtures→ stripes→ hole-stripe mixtures holes→ wave pattern is observed. Our study shows that the spatially extended model system has not only more complex dynamic patterns in the space, but also has spiral waves.