Plant-derived carbon nanospheres for high efficiency solar-driven steam generation and seawater desalination at low solar intensities

In recent times, solar steam generation has proven to be an efficient method for seawater desalination. Herein, we report a novel solar evaporator designed with plant-derived carbon nanospheres obtained from Cinnamomum camphora incorporated in a polyvinyl alcohol sponge (C@CPVA). The fabricated evaporation device produced steam at a rate of 1.53 kg m(-2) h(-1) under 1 sun illumination which was 3.25 times the bare water system. The device further exhibited an outstanding photothermal efficiency of 92.38%, owing to its indirect capillary water pathway design. Furthermore, the C@CPVA array, when integrated in a facile laboratory solar still, generated clean water with an excellent salt removal efficiency of 99.99%. The C@CPVA solar still had exceptional performance even at low, non-concentrated solar intensities, thus enabling its application in practical solar desalination. Finally, the distinct merits of C@CPVA solar still such as excellent low solar intensity performance, facile fabrication and low cost advocate its rapid scaling up to large scale desalination systems. This work should inspire further development of photothermal membrane-incorporated solar stills for non-concentrated, low-intensity solar desalination.