Application of electroactive Au/aniline tetramer-graphene oxide composites as a highly efficient reusable catalyst

In Situ Redox Synthesis of Highly Stable Au/Electroactive Polyimide Composite and Its Application on 4-Nitrophenol Reduction

In this study, we developed a series of Au/electroactive polyimide (Au/EPI-5) composite for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using NaBH₄ as a reducing agent at room temperature. The electroactive polyimide (EPI-5) synthesis was performed by chemical imidization of its 4,4'-(4.4'-isopropylidene-diphenoxy) bis (phthalic anhydride) (BSAA) and amino-capped aniline pentamer (ACAP). In addition, prepare different concentrations of Au ions through the in-situ redox reaction of EPI-5 to obtain Au nanoparticles (AuNPs) and anchored on the surface of EPI-5 to form series of Au/EPI-5 composite. Using SEM and HR-TEM confirm the particle size (23-113 nm) of the reduced AuNPs increases with the increase of the concentration. Based on CV studies, the redox capability of as-prepared electroactive materials was found to show an increase trend: 1Au/EPI-5 < 3Au/EPI-5 < 5Au/EPI-5. The series of Au/EPI-5 composites showed good stability and catalytic activity for the reaction of 4-NP to 4-AP. Especially, the 5Au/EPI-5 composite shows the highest catalytic activity when applied for the reduction of 4-NP to 4-AP within 17 min. The rate constant and kinetic activity energy were calculated to be 1.1 × 10^-3 s^-1 and 38.9 kJ/mol, respectively. Following a reusability test repeated 10 times, the 5Au/EPI-5 composite maintained a conversion rate higher than 95%. Finally, this study elaborates the mechanism of the catalytic reduction of 4-NP to 4-AP.

A novel Au/electroactive poly(amic acid) composite as an effective catalyst for p-nitrophenol reduction

A Au/electroactive poly(amic acid) (Au/EPAA) composite was synthesized and characterized, and its catalytic ability was evaluated. EPAA was synthesized via oxidative coupling polymerization and Au nanoparticles were anchored to the amino and carboxyl groups. The Au/EPAA composite was characterized via X-ray diffraction analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy, which confirmed that the Au nanoparticles were well dispersed on the EPAA surface. p-Nitrophenol was reduced to p-aminophenol within 5 min at room temperature, with a rate constant of 0.84 min⁻¹. Cycling measurements showed that the Au/EPAA composite achieved higher than 92% conversion. The Au/EPAA composite showed excellent performance and stability as a catalyst for the reduction of p-nitrophenol to p-aminophenol.

The Au/EPAA composite demonstrated excellent performance and stability as a catalyst for the reduction of p-nitrophenol to p-aminophenol.