Electrochemical Preparation of Graphene Membrane for Continuous Water Vapor and Crystalline Salt Production

Graphene has high application value in photothermal conversion fields because of the thinness, ultra-lightness, and excellent photothermal properties. However, the traditional methods for preparing commercial graphene were less efficient and more expensive. Herein, the graphene suspensions were prepared using a convenient and environmentally friendly electrochemical exfoliation method. The graphene photothermal conversion (E-GR) membranes were obtained to investigate the effect of electrochemical preparation conditions on the photothermal conversion performance. The evaporation rate of E-GR membrane was 1.267 kg m⁻² h⁻¹ under 1 sun, achieving a solar-to-steam conversion efficiency of 79.65%. In the continuous salt crystallization experiment, the E-GR membrane achieved desalination and uninterrupted fresh water and salt production for 7 days, resulting in the generation of 23.451 kg m⁻² d⁻¹ fresh water and 0.654 kg m⁻² d⁻¹ crystalline salt. During this period, the crystalline salt was formed only at the edges with no obvious crystallization on the surface. Because of the characteristic that graphene can provide a large number of adsorption sites, combined with the capillary action of filter paper, the membrane can be wetted in a short time. Overall, this simple, cost-effective and efficient preparation method greatly promotes the application of graphene in the field of seawater desalination.