Direct solar steam generation (DSSG) offers a promising, sustainable, and environmentally friendly solution to the energy and water crisis. In the past decades, DSSG has gained tremendous attention due to its potential applications for clean water production, desalination, wastewater treatment, and electric energy harvesting. Even though the solar–thermal conversion efficiency has approached 100% under 1 sun illumination (1 kW m−2) using various photothermal materials and systems, the optimization of the materials and system structure remains unclear because of the lack of evaluation methods in unity for the output efficiency. In this review, a few key concerns about different dimensional materials and systems that determine the characteristics of DSSG are explored. Quantitative analysis, including calculations and methods for the solar–thermal conversion efficiency, evaporation rate, and energy loss, is employed to evaluate the materials and systems from the point of view of ultimate utilization. This article focuses on the relationship between the system dimension and energy efficiency and notes opportunities for future system design and commercialization of DSSG.

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Simultaneous production of clean water and electricity using solar energy has been proposed as a promising solution to water scarcity and electricity shortage. Here, we design a thermoelectricity-freshwater cogenerator based...

Energy matching strategy is verified as an effective method for significant improvement of evaporation rate in direct solar steam generation (DSSG). By adjusting the solid-liquid interface through bilayer structure, the water transport speed from reservoir to evaporation surface is controlled to reduce the required energy (RE) for closely matching with that of input energy (IE). The highest evaporation rate can reach up to 2.22 kg m À2 h À1 under one-sun illumination, which is improved by 40% through energy matching. A solar-to-vapor energy conversion efficiency of 93.2% is obtained. It is also highly effective in practical applications including desalination, sewage treatment, oil-water separation, and heavy metal ions treatment. This concept displays a balance between the energy needed for water waiting to be evaporated and the IE. It can inspire more ideas for researchers to accelerate the development of DSSG.

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