Efficiency enhancement on the solar steam generation by wick materials with wrapped graphene nanoparticles

Highlights: • A low-cost high-efficiency solar steam generator using wick material with wrapped nanoparticles was proposed. • By the chemical wrapping method, the nanoparticles coated on wick material have better dispersity and stability. • The wick material with dense fluffs which can provide more wrapping area contributes to better evaporation. -- Abstract: Solar steam generation technology can utilize abundant and renewable solar energy for many applications. In this work, we proposed a low-cost high-efficiency solar steam generator by using wick materials with wrapped graphene nanoparticles, and the energy efficiency can reaches up to 80%. Instead of traditional smearing method, the chemical wrapping method was used for better coating the graphene nanoparticles on the wick materials. Through the SEM morphological results, the graphene nanoparticles are shown to be evenly wrapped across the fibres of the wick material, which have better dispersity and stability. The evaporation rate, instantaneous energy efficiency and the solar absorptivity of three wick materials with/without nanoparticles under different conditions were compared and analyzed. Among the three different wick materials, the fine fluffy cloth can provide more three-dimensional contact area for wrapping graphene nanoparticles and thus contribute to better evaporation. Additionally, the influence of two different reduction methods and different concentrations of graphene oxide solution on the energy efficiency was also analyzed. Our work offers a simple and effective way of using nanotechnology in practical application for better solar-to-heat conversion.