Electrochemical properties of lignin/polypyrrole composites and their carbonized analogues

Lignin/polypyrrole composites were prepared by single-step coating of water-insoluble kraft lignin with polypyrrole. The polymerization of pyrrole was performed with and without the presence of methyl orange, leading to the formation of polypyrrole films of two different morphologies, globular and nanotubular, respectively, on the lignin surface. Such composites were converted to double-carbon composites enriched in inert atoms by pyrolysis in nitrogen atmosphere at 650 °C. The carbonization process was followed by thermogravimetric analysis and confirmed by Raman spectroscopy. The properties of all composites were investigated by FTIR spectroscopy, XPS, EPR, SEM, specific surface area and electrical conductivity measurements. Electrochemical properties were analyzed in terms of their capacitive behavior mainly in acidic solutions, but also in neutral and alkaline media.