Boosting solar steam generation by structure enhanced energy management

Interfacial solar-steam generation is a promising and cost-effective technology for both desalination and wastewater treatment. This process uses a photothermal evaporator to absorb sunlight and convert it into heat for water evaporation. However solar-steam generation can be somewhat inefficient due to energy losses via conduction, convection and radiation. Thus, efficient energy management is crucial for optimizing the performance of solar-steam generation. Here, via elaborate design of the configuration of photothermal materials, as well as warm and cold evaporation surfaces, performance in solar evaporation was significantly enhanced. This was achieved via a simultaneous reduction in energy loss with a net increase in energy gain from the environment, and recycling of the latent heat released from vapor condensation, diffusive reflectance, thermal radiation and convection from the evaporation surface. Overall, by using the new strategy, an evaporation rate of 2.94 kg m−2 h−1, with a corresponding energy efficiency of solar-steam generation beyond theoretical limit was achieved.