| Spray pyrolysis-based synthesis of self-floating black TiO2-x microspheres for solar-driven interfacial evaporation |
Seungheon Han1, Hee Yeon Jeon1, Myeongjun Ji2, Young-In Lee1
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1Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul, 01811, Republic of Korea
2Department of Mechanical Engineering, University of Nevada, Las Vegas, NV, 89154, USA |
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Received: December 13, 2024; Revised: March 14, 2025 Accepted: April 20, 2025. Published online: May 12, 2025. |
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| ABSTRACT |
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While solar-driven interfacial evaporation (SIE) using self-floating monodispersed photothermal microspheres has emerged as a promising method for eco-friendly and continuous clean water production without performance degradation by contaminant accumulation, few studies have been conducted on self-floating SIE due to the lack of appropriate synthesis methods for the self-floating, large-size photothermal particles. In this study, a facile and versatile spray pyrolysis-based process is demonstrated to synthesize self-floating black TiO2-x microspheres. This process facilitates defect engineering within the bulk region of large-sized metal oxides to enhance photothermal properties, a capability that is challenging to achieve with conventional reduction-based methods. The physicochemical properties as a function of process conditions were systematically investigated. The results demonstrated that high concentrations of oxygen vacancies, which were introduced within the bulk region of the black TiO2-x microspheres, extended the light absorption range, improved absorptivity across a wide spectrum, and enhanced photo-to-heat conversion by promoting non-radiative recombination. Consequently, the synthesized defective TiO2-x microspheres exhibited an outstanding solar-driven interfacial evaporation rate of 0.532 kgm-2 h-1. While floating independently without hydrophilic support, the evaporation performance of the self-floating TiO2-x microspheres is 1.63-fold faster than that of bulk water evaporation under light irradiation with an intensity of 1 kWm-2. |
| Key words:
Solar-driven interfacial evaporation · Self-floating · Photothermal metal oxide · Bulk oxygen vacancy · Ultrasonic spray pyrolysis |
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