Nanocomposite of polypyrrole with the nanophotoadduct of sodium pentacyanonitrosylferrate(II) dihydrate and EDTA: A potential candidate for capacitor and a sensor for HF radio wave detection

• Easy synthesis of PPy-photoadduct nanocomposite by chemical oxidation method.
• Nanocomposite synthesis is confirmed by FTIR, XRD and SEM.
• UV–vis spectra depict nanocomposite to act as an NLO material.
• Highly improved thermal stability of nanocomposite than pure PPy.
• High capacitive effect and sensing ability of nanocomposite from dielectric study.

This paper reports the synthesis of nanocomposite involving polypyrrole (PPy) and nanophotoadduct based on sodium pentacyanonitrosylferrate(II) dihydrate and EDTA by in situ chemical oxidation method using FeCl3 as oxidant. Nanophotoadduct was obtained by photo labialization of ligands in sodium pentacyanonitrosyl(II) dihydrate and their subsequent replacement with ethylenediaminetetraacetic acid (EDTA) by a photo lamp which was then reduced to nano size by high energy Ball mill. Successful synthesis of nanophotoadduct and its nanocomposite with PPy was verified by FTIR. Empirical formula of nanophotoadduct was found to be Na2[Fe(CN)(EDTA)(NO)] from elemental analysis and EDX. Polycrystalline nature of nanophotoadduct and its uniform distribution in PPy matrix is well evident from XRD and SEM. UV–vis spectra of nanophotoadduct and nanocomposite showed wider transparency in entire visible region exhibiting the nanocomposite to act as an NLO material. Band gap obtained was found to be 3.8 eV indicating insulating nature of nanocomposite. Parameters like grain size (D), microstrain (ɛ), dislocation density (δ), distortion parameter (g) and d-spacing were also evaluated from XRD. Particle size obtained from XRD is confirmed by TEM. TG/DSC revealed higher thermal stability of nanocomposite compared to pure PPy since decomposition temperature (Ti) for PPy shifts from 250 to 500 °C in nanocomposite thereby allowing its use in devices which operates at high temperatures. From dielectric measurements, an appreciable value of dielectric constant (11 × 106) at frequency below 103 Hz shows high capacitive effect and a very high ac-conductivity of the order of 1013 S/m at around 6.3 MHz, hence the material can find its use in the detection of high frequency (HF) radio waves.

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