CoCr2O4 Nanoparticles with Abundant Oxygen Vacancies: A New Photothermal Platform for Efficient Solar Evaporation

Solar-driven interfacial photothermal evaporation has been recognized as a green, economical, and efficient water purification technique in recent years, and it is one of the most promising methods to realize the supply of high-quality freshwater resources. The key and challenge to achieving a superior water evaporation rate is to explore novel stable materials with high light absorption and photothermal conversion efficiency. In the present work, CoCr2O4 nanocrystals containing a large number of oxygen vacancies have been successfully prepared. Due to their substantial localized surface plasmon resonance effect and excellent photothermal performance, they are applied in the field of solar photothermal water evaporation for the first time. Thanks to their extremely high photothermal effect and excellent hydrophilicity, the outstanding water evaporation rate and efficiency of the obtained CoCr2O4 nanoparticles under standard sun irradiation are as high as 2.26 kg m–2 h–1 and 93.2%, respectively. This work provides an effective strategy for the development of new solar-driven interfacial evaporation materials.