Reduced Enthalpy in Solar Interfacial Evaporation by β-Cyclodextrin/MnO ₂ Heterointerfacial Modulation

Under concentrated sunlight with a high operation temperature (>100 °C), the enthalpy reduction performance of interfacial materials still remains largely unexplored, which is crucial for future large-scale industrial seawater desalination. Here, an interfacial material that can reduce the evaporation enthalpy under high solar concentration was developed by chemically grafting cyclodextrin (CD) onto porous MnO2 (β-CD-MnO2). Experiments demonstrate a 31.5% reduction in the evaporation enthalpy in the β-CD-MnO2 system, which has an evaporation rate of 1.76 kg·m–2·h–1. Our molecular dynamic simulations reveal that the enthalpy reduction arrives from the existence of water-cluster evaporation promoted by the intermediate water. The large existence of intermediate water content in β-CD-MnO2, which was observed in REMAN measurements, is attributed to the heterostructures, the silane linker, and the ring structure of cyclodextrin in β-CD-MnO2. Both outdoor experiments and concentrated solar experiments (13 suns) demonstrate that the β-CD-MnO2 evaporator could realize highly efficient interfacial evaporation with stable enthalpy reduction characteristics.