An Integrated Photocatalytic and Photothermal Process for Solar-Driven Efficient Purification of Complex Contaminated Water

With the water and energy crises becoming critical issues for an increasingly industrialized society, solar-driven water purification technologies are highly desired for both potable water production and wastewater treatment. Herein, the performance of an integrated photocatalytic and photothermal composite, TiO2/Au-carbon nanotube (TiO2/Au-CNT)-coated SiC ceramic plate, in complex contaminated water treatment driven by solar energy is investigated. The short-wavelength part of the solar spectrum is used for simultaneous photo-oxidation of rhodamine B (RhB) (oxidation efficiency of ≈98.5%) and photo-reduction of Cr(VI) (reduction efficiency of ≈90.6%) in an integrated solar still device. A Z-scheme charge transfer mechanism with CNTs as an electron mediator is proposed and discussed for TiO2/Au-CNT-coated SiC ceramic plate. Meanwhile, the design here allowed the long-wavelength part of the solar spectrum to be utilized for high-quality potable clean water production via solar distillation with a solar-to-water evaporation efficiency of ≈72%. Therefore, this integrated photocatalytic and photothermal system can be utilized for potable water production and wastewater treatment in the same device with high solar energy utilization efficiency.