Jiangjin Han, Zhiyue Dong, Liang Hao, Jiang Gong*, Qiang Zhao*

Poly(ionic liquid)-crosslinked graphene oxide/carbon nanotube membranes as efficient solar steam generators

Green Energy & Environment (2021) Accept (IF2020 = 6.395)

Graphene oxide (GO) is regarded as a promising candidate to construct solar absorbers for addressing freshwater crisis, but the easy delamination of GO in water poses a critical challenge for practical solar desalination. Herein, we improve the stability of GO membranes by a self-crosslinking poly(ionic liquid) (PIL) in a mild condition, which crosslinks neighbouring GO nanosheets without blemishing the hydrophilic structure of GO. By further adding carbon nanotubes (CNTs), the sandwiched GO/CNT@PIL (GCP) membrane displays a good stability in pH=1 or 13 solution even for 270 days. The molecular dynamics simulation results indicate that the generation of water nanofluidics in nanochannels of GO nanosheets remarkably reduces the water evaporation enthalpy in GCP membrane, compared to bulk water. Consequently, the GCP membrane exhibits a high evaporation rate (1.87 kg m^-2 h^-1) and displays stable evaporation rates for 14 h under 1 kW m^-2 irradiation. The GCP membrane additionally works very well when using different water sources (e.g., dye-polluted water) or even strong acidic solution (pH=1) or basic solution (pH=13). More importantly, through bundling pluralities of GCP membrane, an efficient solar desalination device is developed to produce drinkable water from seawater. The average daily drinkable water amount in sunny day is 10.1 kg m^-2, which meets with the daily drinkable water needs of five adults. The high evaporation rate, long-time durability and good scalability make the GCP membrane an outstanding candidate for practical solar seawater desalination.