Encapsulation of MXene/polydopamine in nitrogen-doped 3D carbon networks with high photothermal conversion efficiency for seawater desalination

With the rapid consumption of traditional fossil energy, the utilization of solar energy via photothermal conversion to obtain fresh water from seawater or wastewater should be a promising alternative to solve the shortage of energy resources. At present, evaporators based on diverse photothermal conversion materials have been developed, but most of them are still facing the drawbacks of complicated structure, complex preparation and poor salt resistance, which severely affect their broad practical applications. Multilayer-MXene (mMXene) and polydopamine (PDA) nanoparticles are two kinds of materials with excellent photothermal conversion efficiency. In this study, we loaded these two materials with optimized mass ratio into the thermally insulated and low-cost melamine foam, followed by simple annealing treatment to afford three-dimensional and self-floating carbonized MXene/PDA foam (CMPF) evaporators with high hydrophilicity, unpleasant thermal conductivity, and remarkable light absorbance. The evaporation rate of CMPF, as a result, could attain 1.598 kg m-2 h-1 under 1 sun (1 kW m-2) irradiation while the photothermal conversion efficiency is calculated to be 89.8%. In addition, CMPF-2 displays excellent desalination ability, self-desalination ability, good cycle stability and reliable safety performance as revealed by bacterial culture experiment. Combining these advantages, it has been revealed that CMPF-2 possesses certain feasible practical applications in seawater desalination.