Robust direct solar water production by integrating interfacial evaporation and membrane distillation

Interfacial solar vapor generation (ISVG) is an important technique for producing water with a minimal carbon footprint. For customers who need a lot of water, the state-of-the-art ISVG devices are unbearable and unacceptable because of their low condensation capacity. This paper introduces a novel configuration that integrates ISVG and direct contact membrane distillation (DCMD) devices to increase the water yield. A carbon nanoparticle-based solar absorber that can collect 94.6 % of incident sunlight and has a substantial water supply capacity is employed for ISVG. For high vapor permeability, moreover, a hydrophobic polyvinylidene fluoride membrane with a moderate pore structure is adopted. The result shows that the ISVG-DCMD device has a water productivity of up to 2.71 kg m−2h−1 under 2 sun illumination. More importantly, the system has a sustainable water productivity of 2.08 kg m−2h−1 when operating in NaCl solution with a concentration of 3.5 % (w/w). This work effectively solves the problem of vapor condensation of the interfacial photothermal evaporator, offering a novel concept for scalable and robust direct solar water production.