Investigation of the catalytic effect of defective Ni-MOF-74 on polymerization of dopamine and multi-pore polydopamine photothermal coating constructed with defective Ni-MOF-74 particles

Photothermal coating is an effective way to convert the seawater into fresh water, which is controlled by the light utilization capacity and micro-channel for the vaporation of water. In order to improve the effect of water evaporation and water purification driven by sunlight, polydopamine (PDA) coating with more micro-channel and high bonding was formed through the introduction of porous material and 3-Aminopropyltriethoxysilane (AMEO). Compared with Ni-MOF-74, defective Ni-MOF-74 could produce more coordination with dopamine and promote the polymerization of dopamine, resulting in the formation of sea cucumber structure, which is foundation for the micro-channel of the deposition coating of PDA. Also, depending on the sea cucumber structure, the as-prepared coating of PES/PDA/MOF-30 mg by the two-solvent strategy possesses the water evaporation rate of 1.85 kg/(m2·h), the photothermal conversion efficiency of 98.4%, the retention rate of alkali metal and heavy metal ions above 99% and good long-term stability. The coating with good comprehensive property is good choice for the water purification. [Display omitted] •Defective MOF-74 can promote the polymerization of dopamine in neutral solvent.•The sea cucumber topological particles with greater light absorption were obtained by AMEO-based two-solvent system.•PES/PDA/MOF-30mg showed excellent solar-driven water evaporation properties (1.85 kgm−2h−1 and 98.4 %).•The retention rate of alkali metal and heavy metal ions by PES/PDA-AMEO and PES/PDA/MOF-30 mg was above 99%.