pH-Responsive Polyoxometalate-Based Supramolecular Hybrid Nanomaterials and Application as Renewable Catalyst for Dyes

Keggin-type polyoxometalate (POM), phosphotungstic acid (H₃PW₁₂O₄₀), was encapsulated by an oppositely charged COOH-functionalized surface active ionic liquid (SAIL), N-decyl-N′-carboxymethyl imidazolium bromide ([N-C₁₀, N′-COOH-Im]­Br), with the assistance of an ionic self-assembly (ISA) process in an aqueous environment. The as-prepared POM/SAIL material possesses multiple active properties, including reversible pH-response and renewable catalyst for dye degradation. Specifically, the POM-based hybrid materials show a great enhancement in catalytic efficiency when it is employed in degradation of methyl orange (MO) in aqueous solution. Furthermore, the electrostatic repulsions between POM and the deprotonated SAIL may result in the pH-induced disassembly and assembly of the hybrid nanomaterials, which provides an expedient method to regenerate the catalytic activity. Therefore, the presented POM/SAIL hybrid materials are expected to improve the common poisoning issue of the traditional heterogeneous catalysts for industrial applications.