This comprehensive review provides a guide to design photothermal materials and systems for solar-driven water evaporation addressing the water–energy nexus.

Solar-driven photothermal conversion by nanostructured materials is a direct solar energy conversion process that has been used as a novel strategy to augment vaporization and catalysis performance.

Solar vaporization has received tremendous attention for its potential in desalination, sterilization, distillation, etc. However, a few major roadblocks toward practical application are the high cost, process intensive, fragility of solar absorber materials, and low efficiency. Herein an inexpensive cellular carbon sponge that has a broadband light absorption and inbuilt structural features to perform solitary heat localization for in situ photothermic vaporization is reported. The defining advantages of elastic cellular porous sponge are that it self‐confines water to the perpetually hot spots and accommodates cyclical dynamic fluid flow‐volume variable stress for practical usage. By isolating from bulk water, the solar‐to‐vapor conversion efficiency is increased by 2.5‐fold, surpassing that of conventional bulk heating. Notably, complementary solar steam generation‐induced electricity can be harvested during the solar vaporization so as to capitalize on waste heat. Such solar distillation and waste heat‐to‐electricity generation functions may provide potential opportunities for on‐site electricity and fresh water production for remote areas/emergency needs.

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can attain the highest achievable conversion efficiency and enable a broad range of applications, including domestic heating, brine desalination, wastewater purification, steam sterilization, and power generation. [1][2][3][4][5][6][7] One actualization of solarto-thermal technology, solar-driven water evaporation can directly transfer heat to drive evaporation using sunlight as the only power input. [8][9][10][11][12][13][14][15] Compared with the conventional solar-driven steam generation system which requires high optical devices and large footprints investment, the emerging interfacial photothermal water evaporation based on nanostructured solar receiver materials restrict the solar heat at the water-air interface to suppress the heat losses and enhance the conversion efficiency. To date, significant progress in preparation of solar absorber materials, including semiconductors, [16][17][18] metallic, [19][20][21] and carbonaceous nanomaterials, [22][23][24][25] alongside with prudent system designs, e.g., environmental enhancement, [26][27][28] optical, [28][29][30] and thermal management [31][32][33] The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/aenm.201900250. Photothermal ConversionSolar energy is an inexhaustible energy source for the development of sustainable energy technology. Solar-to-thermal technology is a direct strategy for harvesting solar energy, which Adv. Energy