Bifunctional Cu2-xSe-decorated hierarchical TiO2 nanotube mesh with solar water evaporation and photodegradation effects for clean water generation

The desalination and purification of sea or brackish water by utilizing solar energy are considered to be the most feasible solutions to overcome the problems of water shortage and pollution. In this study, a bifunctional Cu2-xSe-decorated hierarchical TiO2 nanotube mesh (CTNM) was designed and synthesized successfully for both solar water evaporation and photodegradation. Cu2-xSe enhances solar light absorption and solar water evaporation performance as a low-cost absorber because of its localized surface plasmon resonance (LSPR) effect. Meanwhile, the formation of the p-Cu2-xSe/n-TiO2 heterojunction improves the photodegradation performance by increasing separation and transport of photogenerated charge carriers. Hence, CTNM has a relatively high solar water evaporation conversion efficiency of 83.06% and also can photodegrade 95% of methyl orange after 3 h under 2.5 kW m(-2) simulated solar irradiation, which demonstrate the extremely high utilization ratio of solar energy of CTNM.