Three-dimensional water evaporation on a macroporous vertically aligned graphene pillar array under one sun

Abstract

Efficient harvesting of solar radiation into exploitable thermal energy for fast generation of clean water has been a recent research focus. However, solar steam generation (SSG) is generally limited to unidirectional evaporation, and the production rate is still low. Herein, we develop three-dimensional water evaporation based on a highly vertically ordered pillar array of graphene-assembled framework (HOPGF) with an enlarged evaporation area and additional free space for fast escape of vapour. As a result, a high water evaporation rate of 2.10 kg m⁻² h⁻¹ is achieved under only 1 sun. This efficient SSG system exhibits practical ability to treat sewage by the purification of raw pharmaceutical wastewater. On the other hand, a solar water heater based on HOPGF is conceptually proposed and experimentally designed through 3D printing technology, which presents the potential to heat 30 kg water to ca. 50 °C with only one square meter of HOPGF under 1 sun within hours. Promisingly, a housing self-supply water system was built to verify the effectiveness for high production of clean water. This work develops an efficient HOPGF material platform for construction of fast and scalable solar water-generating and water-heating systems of practical importance.