Defects in In2O3/TiO2 composite boosting photothermal conversion for water purification and electricity generation

Solar-driven interfacial evaporation for sustainable production of clean water from seawater and organic wastewater is viewed as a cutting-edge and practical technology to solve the shortage of fresh water. Here, we provide a novel strategy for constructing oxygen vacancy-rich In2O3/TiO2 composite to apply in water purification. It is found that oxygen vacancy enhances light absorbance, reduces light reflection, and decreases the thermal conductivity, being beneficial for photothermal conversion and heat confinement. On the other hand, oxygen vacancy-rich In2O3/TiO2 composite offers an excellent photocatalytic degradation, which can improve the quality of the purified water and keep surface and interface clean, and thus enhance durability of photothermal material. To compare with In2O3/TiO2, In2O3/TiO2* with rich oxygen vacancies markedly enhances the evaporation rate of pure water from 1.04 to 1.51 kg m−2h−1 under 1 sun illumination, corresponding photothermal conversion efficiencies of 58.6% and 90.3%, respectively. Furthermore, the evaporator constructed with In2O3-TiO2* displayed 1.47 and 1.49 kg m−2h−1 for seawater and lake water, respectively, close to pure water under 1 sun illumination. Besides, this evaporator also offered an excellent purification and photocatalytic degradation for organic wastewater during the solar-driven evaporation. Importantly, this evaporator also could synergistically generate electricity, achieving a maximum electrical power of 1.23 W m−2 under 1 sun. This work demonstrates the preponderance of the oxygen vacancy-rich material, and expands the application of the defected In2O3/TiO2 composite in solar-driven interfacial evaporation.