Side-chain design approach for au-immobilized electroactive poly(amic acid) as magnetically recyclable catalyst toward rapid 4-nitrophenol reduction

Nitrophenolic compounds such as 4-nitrophenol (4-NP), are hazardous and recalcitrant pollutants widely found in industrial effluents. Efficient catalytic reduction of 4-NP to 4-aminophenol (4-AP) requires nanocatalysts with rapid electron transfer and reusability criteria often unmet by conventional polymeric supports. Herein, we report a side-chain-engineered electroactive poly (amic acid) (DA-EPAA) featuring pendant aniline pentamers that enable uniform in situ co-immobilization of Au and γ-Fe 2 O 3 nanoparticles, yielding a magnetically separable nanocomposite. Morphological characterization by SEM and TEM showed uniformly dispersed Au nanoparticles (34.7–64.4 nm) on DA-EPAA, while the presence of γ- Fe 2 O 3 confined Au domains to 11.3–35.6 nm, indicating improved dispersion via interfacial stabilization. Redox behavior probed via CV demonstrated pronounced electroactivity of the DA-EPAA backbone. XRD and XPS confirmed the crystallinity and oxidation states of Au 0 and Fe 3+ . TGA analysis indicated Au loading of 17.04 wt% in the hybrid 6Au/DA-EPAA–Fe 2 O 3 composite. The resulting catalyst achieves complete 4-NP conversion within 40 s, with a high pseudo-first-order rate constant of 3.6 × 10 −2 s −1 and over 98 % conversion after ten cycles. This work underscores the potential of side-chain redox polymer matrix for constructing efficient, recyclable nanocatalysts for aqueous-phase pollutant remediation. • Side-chain DA-EPAA synthesized with pendant aniline pentamers for Au/Fe 2 O 3 anchoring. • γ-Fe₂O₃ confined AuNPs size, enhanced dispersion, and enabled magnetic separation. • 6Au/DA-EPAA-γ-Fe 2 O 3 achieved complete 4-NP reduction within 40 s. • Over 98 % catalytic efficiency retained after ten magnetic cycles in aqueous phase.