Reduced graphene oxide (rGO) can improve the thermoelectric properties of polyaniline (PANI) by varying its concentration in composites of rGO nanosheets and PANI. The figure of merit (ZT) of rGO-PANI composites is increased with an increasing percentage of rGO (up to 50%), which is 7.5 times higher as compared to pure PANI. High resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analyses show a uniform growth of PANI over the surface of rGO as a template, leading to a more ordered structure with high crystallinity during polymerization. Compared to pure PANI, both the electrical conductivity and thermoelectric power of the rGO-PANI composite is higher due to the increased carrier mobility as confirmed by a Hall effect measurement. Fourier transform infrared spectroscopy (FTIR), ultra-violet visible range spectroscopy (UV-Vis) and Raman spectroscopy analyses reveal that strong p-p interactions assisted the uniform distribution of PANI on the rGO nanosheets. Other strong interactions include electrostatic forces and hydrogen bonding between rGO and PANI, which provide a route for constructing highly ordered chain structures with improved thermoelectric performance of PANI. There is no significant change in the thermal conductivity of the rGO-PANI composite as compared to pure PANI, which improves the thermoelectric performance of composite.

Bismuth telluride (Bi₂Te₃) nanorods and polyaniline (PANI) nanoparticles have been synthesized by employing solvothermal and chemical oxidative processes, respectively. Nanocomposites, comprising structurally ordered PANI preferentially grown along the surface of a Bi₂Te₃ nanorods template, are synthesized using in situ polymerization. X-ray powder diffraction, UV-vis and Raman spectral analysis confirm the highly ordered chain structure of PANI on Bi₂Te₃ nanorods, leading to a higher extent of doping, higher chain mobility and enhancement of the thermoelectric performance. Above 380 K, the PANI-Bi₂Te₃ nanocomposite with a core-shell/cable-like structure exhibits a higher thermoelectric power factor than either pure PANI or Bi₂Te₃. At room temperature the thermal conductivity of the composite is lower than that of its pure constituents, due to selective phonon scattering by the nanointerfaces designed in the PANI-Bi₂Te₃ nanocable structures. The figure of merit of the nanocomposite at room temperature is comparable to the values reported in the literature for bulk polymer-based composite thermoelectric materials.

Creation of an innovative composite photocatalyst, to advance its performance, has attracted researchers to the field of photocatalysis. In this article, a new photocatalyst based on polyaniline/reduced graphene oxide (PANI/RGO) composites has been prepared via the in situ oxidative polymerization method employing RGO as a template. For thermoelectric applications, though a higher percentage (50 wt %) of RGO has been used, for photocatalytic activity, lesser percentages (2, 5, and 8 wt %) of RGO in the composite have given a significant outcome. Furthermore, photoluminescence (PL) spectra, time-resolved fluorescence spectra, and Brunauer–Emmett–Teller surface area analyses confirmed the improved photocatalytic mechanism. PANI/RGO composites under visible light irradiation exhibit amazingly improved activity toward the degradation of cationic and anionic dyes in comparison with pristine PANI or RGO. Here, a PANI/RGO composite, with 5 wt % RGO(PG2), has emerged as the best combination with the degradation percentages of 99.68, 99.35, and 98.73 for malachite green, rhodamine B, and congo red within 15, 30, and 40 min, respectively. Experimental findings show that the introduction of RGO can relieve the agglomeration of PANI nanoparticles and enhance the light absorption of the materials due to an increased surface area. Moreover, the PG2 composite also showed excellent photocatalytic activity to reduce noxious Cr(VI). The effective removal of Cr(VI) up to 94.7% at pH 2 was observed within only 15 min. With the help of the active species trapping experiment, a plausible mechanism for the photocatalytic degradation has been proposed. The heightened activity of the as-synthesized composite compared to that of neat PANI or RGO was generally because of high concentrations of • OH radicals and partly of • O 2 – and holes (h + ) as concluded from the nitroblue tetrazolium probe test and photoluminescence experiment. It is hoped that the exceptional photocatalytic performance of our work makes the conducting polymer-based composite an effective alternative in wastewater treatment for industrial applications.

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