Enhancing solar absorbance using a 2D graphene oxide/CuO composite film for efficient solar desalination

Abstract

Interfacial solar steam generation (ISSG) is a promising seawater desalination technique owing to the low cost, zero pollution and easy operation involved. In this work, we aimed to develop a novel 2D graphene oxide (GO)/CuO photothermal film via a facile ultrasonication method towards enhanced solar absorbance for highly efficient ISSG. The as-prepared GO/CuO film exhibited a sandwiched nanostructure, where the CuO nanoparticles were confined in the GO layers. This was beneficial to enlarge the spacing of the GO layers, leading to high light reflection in the GO/CuO film. Alternatively, the CuO nanoparticles could promote the incident light absorbance in the whole visible light range. Moreover, the water contact angle of the GO/CuO film was 57.4°, which is much lower than that of the pure GO film (74.8°), suggesting that a high-water transport rate can be expected. Consequently, the highest light absorption of the GO/CuO film was 83% in the entire sunlight range, whereas the corresponding value was 74% for the pure GO film. Under 1 kW m⁻² irradiation, the highest evaporation rate by the GO/CuO film reached 1.71 kg m⁻² h⁻¹ with an efficiency of 99.2%, which remained at 1.60 kg m⁻² h⁻¹ after 20 cycles of desalination. Furthermore, the GO/CuO film was applied to treat organic pollutants, which achieved a high removal efficiency of more than 90%.