Salt-Responsive Fe3O4 Nanocomposites and Phase Behavior in Water

Redox-Responsive Polymer Template as an Advanced Multifunctional Catalyst Support for Silver Nanoparticles

Hybridization of metal nanoparticles (NPs) with redox-switchable polymer supports not only mitigates their aggregation, but also introduces interfacial electron pathways desirable for catalysis and numerous other applications. The large surface area and surface accessible atoms for noble metal nanoparticles (e.g., Ag, Au, Pt) offer promising opportunities to address challenges in catalysis and environmental remediation. Herein, AgNPs were supported onto redox-switchable polyaniline that acts as an advanced multifunctional conducting template for enhanced catalytic activity. At the initial stage of reduction of Ag⁺, leucoemeraldine is oxidized in situ to pernigraniline (PG), which acts as interfacial pathway between NPs for electron transport. With the contribution of BH₄^-, PG acts as an electron-acceptor site, which creates interfacial electron-hole pairs, serving as additional active catalytic reduction sites. The use of a redox-responsive composite system as a template enhances catalyst performance through adjustable charge injection across interfacial sites, along with catalyst reusability for the reduction of 4-nitrophenol (4-NPh). Strikingly, from X-ray photoelectron spectroscopy results it was observed that in situ reduction of Ag⁺ onto the conductive polymer alters the electronic character of the catalyst. The unique multielectronic effects of such Ag-supported NPs enrich the scope of such catalytic systems via a tunable interface, diversified catalytic activity, fast kinetics, minimization of AgNPs aggregation, and maintenance of high stability under multiple reaction cycles.