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This study reports the polymerization of polypyrrole (PPy) in bacterial nanocellulose (BNC) membranes impregnated with manganese oxide (MnO2). Prior to polymerization, nanosized MnO2 is synthesized in situ using H2SO4 and KMnO4. PPy is then polymerized in situ in the MnO2 impregnated BNC membranes via chemical oxidation using copper chloride dihydrate (CuCl2·2H2O) as the oxidizing agent using two different concentrations of pyrrole (Py): 0.04 and 0.08 mol L−1 with a 1:4 molar ratio of Py/CuCl2·2H2O. Assembled symmetric supercapacitor devices exhibit specific capacitances as high as 1073 mF cm−2 (259 F cm−3) and a capacitance retention of 99.5% after 1000 cycles, which show that the combination of BNC membranes with a conductive polymer and a metallic oxide can be promising as an electrode for energy storage devices.

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This work reports the one-step synthesis of bacterial nanocellulose (BNC) incorporated with polypyrrole (PPy) by chemical in situ polymerization of pyrrole (Py) using CuCl2·2H2O as both oxidant agent and functional component, varying the concentration and molar ratio. Electrical, morphological, and physical-chemical properties of these nanocomposites were investigated. The results revealed that with the increase of Py concentration and molar ratio, the nanocomposites presented traces of copper chloride and copper oxide as shown by Raman and XRD analysis. The quality of bacterial cellulose nanofibers coating by the polymer and the electrical conductivity of the nanocomposites was directly affected by those variables. The combination of the conducting polymer with the oxidant agent offers possibilities for different applications such as electronic devices and sensors.

Semiconductor ZnO aerogels were synthesized by a sol-gel process with different concentrations (2.5-7.5 wt.%) of Al (n-type) or Na (p-type) and dried under supercritical CO 2 . The materials were calcined at 500 °C to remove the organic content and to crystallize the ZnO. The microstructure of the ZnO-based aerogels comprises a porous structure with hexagonal and platelet-shaped interconnected particles. The bandgap of the aerogels doped with Al decreased significantly compared to pure, undoped ZnO aerogels, while their specific surface area increased. For the electrical characterization of the ZnO-Na/ZnO-Al junctions, the doped ZnO aerogels were deposited on commercial glass substrates coated with indium tin oxide (ITO) by drop casting method. The I-V curves of the p-n homojuntions revealed a characteristic diode rectifying behavior.

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