A High-Efficiency Ammonia-Responsive Solar Evaporator

Solar evaporator, which is capable of purifying water through solar energy, is a potentially attractive solution to relieve the world-wide water shortage problem. However, there may be toxic and volatile substance, such as ammonia, in the water body, which could be evaporated along with water during the evaporation process, causing contamination of the purified water. In this work, we report an intelligent ammonia responsive high-efficiency solar evaporator based on the titanium dioxide nanoparticle (TiO2NP) and polypyrrole nanoparticle (PPyNP) composite. Owing to the synergistic effect between the photo-induced hydrophilicity of TiO2NP and the photothermal effect of PPyNP, the solar evaporator is able to transport and evaporate water with an efficiency as high as 97.3% and an evaporation rate of 2.9 kg m-2 h-1 (under 2 sun irradiation). Interestingly, due to the ammonia responsiveness, the solar evaporator is smart and stops working in the presence of ammonia, thus avoiding the evaporation of this contaminant. In addition, the current solar evaporator is capable of degrading organic pollutant (e.g. dyes), which relies on the photocatalytic activity of TiO2NP. We thus believe that the responsive solar evaporator reported in the current study may have great potentials in the practical field.