Controlled self-assembly of oligomers-grafted fibrous polyaniline/single zirconium phosphate nanosheet hybrids with potential-responsive ion exchange properties

• The α-ZrP nanosheet/fibrous PANI hybrid film was successfully fabricated by PPM.
• A layer of pre-deposited PANI oligomer can induce the firm polymerization of aniline.
• The amount ratio of α-ZrP and PANI can be regulated by adjusting the pulse width.
• A potential-induced ion exchange process of α-ZrP/PANI film was proposed.
• The resulting α-ZrP/PANI hybrid film shows excellent ESIX performance for Pb2+ ion.

A novel α-zirconium phosphate (α-ZrP) nanosheet-implanted fibrous polyaniline (PANI) hybrid film with potential-responsive ion exchange function is fabricated by a facile pulse electrochemical synthesis technique. The suppression effect of electrical double layer at the conducting substrate/colloidal solution interface for the formation of PANI/α-ZrP hybrid film is effectively improved through a layer of pre-deposited PANI oligomers, whose thickness plays an important role in the self-assembly of the hybrid film. During the pulse electrochemical synthesis process, the oligomers-grafted fibrous PANI is electropolymerized in the period of high potential; and the translucent exfoliated α-ZrP nanosheets are uniformly implanted into the fibrous PANI by electrostatic self-assembly in the following period of low potential. The amount ratio of α-ZrP nanosheet and fibrous PANI can be regulated by adjusting the pulse width based on their growth rate. The results show that the optimized pulse width for the fabrication of PANI/α-ZrP hybrid film with three-dimensional porous structure is 0.8 s. Under this condition, the generated PANI/α-ZrP hybrid film shows fast uptake/release ability and high capacity for the separation of Pb2+ ions from aqueous solution based on its unique potential-induced ion exchange process. The adsorption equilibrium time is less than 30 s, and the ion exchange capacity of porous PANI/α-ZrP hybrid film reaches 123.5 mg g−1, which is almost 9 times higher than that of the compact PANI/α-ZrP hybrid film. Furthermore, the ion exchange capacity retains 85.2% of its initial value after 1000 cycles.

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