Deep co-deposition of polydopamine in PVDF hydrogel to enhance photothermal evaporation efficiency

Polydopamine (PDA) is a widely utilized photothermal conversion material recognized for its ease of synthesis and environmental friendliness. However, its relatively weak light absorption capabilities lead to lower photothermal efficiency, restricting its application in solar steam generation (STG) processes. To effectively enhance light absorption, this study introduces a deep co-deposition method for the microstructural design of STG membranes. Unlike traditional surface co-deposition methods, which coat a layer of PDA on the membrane surface, the deep co-deposition method allows for the incorporation of PDA within the internal nanohydrogel structural units of the membrane. This approach significantly increases the PDA loading, resulting in a marked enhancement of light absorption capabilities. In the near-infrared region (800-2500 nm), where the light absorption of PDA is relatively weak, the absorbance improved from 70.18% (surface co-deposition) to 88.20% (deep co-deposition). While PDA has been extensively studied across various fields, its application as a structural and functional additive in hydrogels remains limited, particularly in comparison to the rapid advancements in PDA-based surface-engineered hydrogels. Thus, this study may provide valuable insights for related research areas.