Flexible CuO-rGO/ PANI thermal absorber with high broadband photoresponse and salt resistance for efficient desalination of oil-contaminated seawater

Abstract

Solar Steam Generation (SSG) is a promising and efficient technology to limit the global water scarcity issue. Nevertheless, it is challenging to utilize versatile photothermal absorbers with salt-resistance and anti-oil-fouling capability through a facile, scalable, and cost-effective fabrication technique. This work demonstrated the combination of cheap semiconductor material with a porous ionic polymer (PIP), emeraldine salt (ES) form of polyaniline (PANI), as salt-resistant and oil-repellent evaporator, which was synthesized through a facile and cost-effective one-step method. PANI enhanced the photoresponse of the CuO-rGO and its honeycomb-like structure increased the photothermal conversion due to the multi-scattering of the incident light. The CuO-rGO/PANI achieved an evaporation rate of 2.02 kg m−2 h−1 and a solar-to-steam efficiency of 94.2% under 1 sun illumination. Furthermore, the composite presented high in-water (138.5°) and in-air (135.2°) oil contact angles with simultaneously high-water affinity (<8°) which proved the hydrophilicity and oleophobicity of this membrane. CuO-rGO/PANI can work effectively in high-concentration brine with no activity loss, due to the “Donnan exclusion” effect generated from cationic quinonoid and benzenoid structure of ES-PANI against cations from saline solution, which exhibit superb durable evaporation performance over 10 cycles.