Lattice distortion and synergistic crystal field: A path to broad-spectrum absorption in high-entropy sulfides for solar water evaporation

Abstract

Solar interfacial evaporation is a promising and sustainable approach to address global water shortages, yet the limited light absorption of existing photothermal materials constrains their efficiency. Here, we present an innovative lattice distortion and synergistic crystal field strategy for designing advanced photothermal materials with broad-spectrum absorption. For the first time, we report ZnCdFeCoNiS, a high-entropy sulfide (HES-NPs) material exhibiting exceptional photothermal conversion efficiency for solar seawater desalination. This HES-NPs achieves an average absorbance of over 92 % across the full solar spectrum (250–2500 nm). It delivers an impressive photothermal conversion efficiency exceeding 93 % under one sun irradiation, alongside a high evaporation rate of 1.92 kg m⁻² h⁻¹. XRD analysis reveals significant lattice distortion in HES-NPs, showing a 4.32 % increase in layer distance for the (111) orientation. DFT calculations and diffuse reflectance spectra indicate this distortion effectively narrows the band gap. Additionally, the introduction of multiple transition metals creates overlapping crystal fields, creating synergistic e_g and t_2 g states. This approach not only reduces the layer gap but also enhances interband transitions, thereby broadening the light absorption range and boosting absorption efficiency. This lattice distortion and synergistic crystal field approach not only optimizes the photothermal properties of HES-NPs but also establishes a new design paradigm for high-performance materials in solar-driven water evaporation and desalination applications.