Composite fabric with high photoabsorption and conductivity for efficient all-weather seawater desalination under low voltage

Abstract

Photo/electro-thermal desalination has been considered an effective strategy to obtain freshwater continuously from seawater, but its practical application is still hindered by weak photoabsorption, high voltage-dependent evaporation and salt precipitation. To address these problems, we report a photo/electrothermal fabric for achieving efficient continuous all-weather evaporation. Such fabric is prepared by coating graphene oxide-polyvinyl alcohol (GO-PVA) on conductive carbon fiber cloth (CFC) through a brushing-crosslinking route. GO-PVA hydrogel coating enables the transformation of hydrophobic CFC into super-hydrophilic CFC@GO-PVA, accompanied by the decrease in evaporation enthalpy to 1917.36 kJ kg⁻¹ compared with pure water (2408 kJ kg⁻¹). CFC@GO-PVA fabric shows high photoabsorption efficiency (95.9 %) in 280–2500 nm and good photothermal effect. When CFC@GO-PVA is used to construct a hanging heliotropic evaporator, it exhibits a photothermal evaporation rate of 2.31 kg m^-2h⁻¹ under 1 sun illumination. Simultaneously, CFC@GO-PVA fabric has excellent electrothermal conversion performance owing to the conductive property of CFC and the heat transfer channel of GO, and an electrothermal evaporation rate of 10.39 kg m^-2h⁻¹ can be achieved at low voltage (3 V). Interestingly, with the combined effect of 1 Sun and 3 V, CFC@GO-PVA fabric reaches a remarkable evaporation rate of 14.16 kg m^-2h⁻¹. The present high synergetic evaporation performance is attributed to the high photo-electrothermal coupling temperature which can reduce water viscosity, yielding a faster interface-water–vapor escape. Importantly, the fabric demonstrates good stability without salt crystallization during long-time evaporation tests. Therefore, the present study offers a new perspective on designing photo-electrothermal materials for all-weather seawater evaporation.