Highly stable TiO2 ceramics for high efficiency and practical solar-driven interfacial evaporation

Solar-driven interfacial evaporation has attracted widespread attention due to its high solar evaporation efficiency and transformative industrial potential. However, previous studies have primarily focused on innovation of solar absorbing materials, while neglecting the interfacial instability between solar absorbing materials and porous supporting substrates, which limits their practical application. In this work, we demonstrate that TiO2 ceramics obtained via high-temperature vacuum sintering can simultaneously function as a solar absorbing material and a porous supporting substrate, and thus eliminate the interfacial instability through a strategy of forming an all-in-one structure. The resulting TiO2 ceramics exhibit a significant increase in absorbance of 407.8% compared to the original TiO2 in the solar spectrum range, owing to their surface defect layers and massive pores. Furthermore, a TiO2 ceramic-based evaporator was developed with an excellent heat management capability, resulting in a 43.1% reduction in thermal loss to bulk water. Finally, the TiO2 ceramic-based evaporator demonstrated an excellent evaporation rate of 1.22 kg/m2/h under indoor simulated one sun irradiation (1 kW/m2) and an average evaporation rate of 0.55 kg/m2/h under natural sunlight with an average irradiance of 0.42 kW/m2. This work not only demonstrates for the first time the possibility of applying TiO2 ceramics in solar-driven interfacial evaporation, but also highlights the enormous potential of ceramic materials in advancing the field of solar-driven interfacial evaporation.