Electrochemical oxidation reconstructs graphene oxides on sponge for unprecedentedly high solar water evaporation

Although carbon nanomaterials are featured with low cost, outstanding solar-harvesting ability, ultrahigh stability and easy availability, their constructed evaporators still possess low evaporation rate so far under natural sunlight condition. Herein, we present an efficient electrochemical oxidation method to tailor chemical compositions and microstructures of graphene oxides (GO) upon porous melamine sponge (MS) for establishing ultrafast solar water evaporation system. Thanks to superior water activation property resulted from electrochemical oxidation, the afforded evaporation system is able to significantly reduce the water vaporization enthalpy, thereby exhibits a high evaporation rate of 3.47 kg m −2 h −1 with the solar-to-steam conversion efficiency of 97.4% under one-sun irradiation, which outweighs all of reported evaporators constructed by congeneric photothermal materials. Furthermore, this evaporation system displays outstanding mechanical performance and satisfactory tolerance to various harsh conditions. With long-term stability and good durability, this evaporation system provides a possibility of large-scale water purification with natural sunlight to meet the world ever-increasing demands for freshwater. After tailoring chemical compositions and microstructures of graphene oxides via electrochemical method, the constructed evaporator exhibits a high evaporation rate of 3.47 kg m −2 h −1 with the solar-to-steam conversion efficiency of 97.4% under one-sun irradiation.