Construction of a quadra-functional MXene-mediated photocatalytic solar-driven interfacial evaporation materials: The regulation strategy of MXene in enhancing seawater evaporation and degradation

Solar-driven desalination is a promising approach for alleviating water shortages. However, the low evaporation rate severely restricts the widespread application of solar evaporation materials. In this study, an MXene was developed as a cross-linker and photothermal material and then combined with BiOBr to create a photoinitiator and photocatalyst for synthesizing MXene-based aerogels. Owing to MXene contents influenced the pore size and light-absorption ability of aerogel, and further significantly impacted the water transmission and photothermal conversion properties of aerogel, the water evaporation rate could be elevated by regulating the content of MXene. The optimal aerogel exhibited excellent light-absorption capacity (~92 %), super-hydrophilicity (water contact angle reaching 0° in less than 1 s), low thermal conductivity (0.03212 W m⁻¹ K⁻¹), appropriate pore-size distribution (concentrated in the 9.6–30.8 μm range) and high toughness. Under 100 mW cm⁻² irradiation, the water evaporation rate and photothermal conversion efficiency of the optimal aerogel were 1.73 kg m⁻² h⁻¹ and 88.36 %, respectively. Furthermore, no significant salt accumulation was observed at the surface even after 10 h of cyclic evaporation. When seawater was contaminated with organic pollutant (e.g. rhodamine B (RhB)), the aerogel achieved photo-decolorization efficiency of 99.12 % and salt ions removal rate of 99.5 %. Therefore, the obtained aerogel with integrated high evaporation rates and photocatalytic characteristic meets the trend of “multi-function integration” and is expected to offer an effective solution for addressing the global water scarcity issue.