NiFe₂O₄/GO-Incorporated Nanohybrid Polymers for Multi-Modal Sensing and Electrocatalytic Oxidation of Phenols

Here, purely aliphatic electroactive fluorescent polymers ( EFP s) are synthesized employing butyl acrylate and methacrylic acid monomers. The optimum extent of −COOH, −COO –, and −COO–(CH 2 ) 3 –CH 3 subfluorophores in EFP2 is indicated by Fourier-transform infrared (FTIR) and nuclear magnetic resonance spectroscopies. Subsequently, five dual-state emissive magnetic electroactive fluorescent nanohybrid polymers ( EFNHP s) are synthesized by encapsulating magnetic NiFe 2 O 4 /graphene oxide (GO) nanoparticles in EFP2 . Among the EFNHP s, EFNHP3 imparts the best optical, sensing, and electrochemical proficiencies through the optimal inclusion of NiFe 2 O 4 /GO nanoparticles and −COOH/–COO – /–COO–(CH 2 ) 3 –CH 3 subfluorophores, as indicated by FTIR spectral analyses and conductivity/fluorescent enhancement measurements. The structural features, metal–oxygen/H-bonding interactions, and magnetic properties of EFNHP3 are explored by spectroscopic/diffractometric/microscopic analyses and vibrating sample magnetometer measurements. In EFNHP3, Förster resonance energy transfer-associated dual-light emissions in solid state/solution are explored by excitation-dependent emissions, significant merging of NiFe 2 O 4 /GO absorption with EFP2 emission, quantum yields/Stokes shifts, lifetime measurements, solvent polarity effects, concentration-dependent emissions, and aggregation-enhanced emissions. In solution, EFNHP3 endows a high conductivity of 0.47262 S cm –1 . The notable optoelectronic characteristics enable EFNHP3 to be a sensitive/selective fluorometric phenol (PhOH) sensor and fabricate an EFNHP3 -GCE electrode for electrochemical/impedimetric sensing-oxidation of PhOH through cooperative electrocatalysis involving Fe(III)/Fe(II), Ni(II)/Ni(0), and EFP2 in aqueous medium. The sensing and electrocatalytic oxidation of PhOH are supported by fluorescence/ultraviolet/FTIR/impedance spectral analyses, diffractometric/lifetime/dynamic light scattering data, and cyclic voltammetric measurements. In fluorometric, electrochemical, and impedimetric PhOH sensing, the limits of detection are measured to be 22.61, 152.36, and 140.11 nM in an aqueous medium, respectively.