Hierarchically porous fibrous carbon containing Fe3O4 particles and doped with both N and S derived from polypyrrole modified lignosulphonate-bacterial cellulose for use in high performance supercapacitors
The design of heteroatom-doped porous carbon materials integrated with metal oxide nanostructures has emerged as an efficient approach for improving the electrochemical performance of supercapacitors. A green and cost-effective method is reported for the fabrication of a hierarchical porous carbon composite from bacterial cellulose (BC), lignosulfonic acid (LS), and polypyrrole (PPy). LS serves as both an anchoring agent and a soft molecular template, directing the oxidative polymerization and uniform deposition of PPy onto the BC nanofibers in the presence of FeCl3 as the oxidizing agent. Subsequent carbonization under a nitrogen atmosphere results in the formation of an N/S co-doped carbon framework decorated with Fe3O4 nanoparticles, denoted C-BCLP. For comparison, a control composite consisting of BC and PPy without LS was carbonized to produce C-BCP. X-ray diffraction patterns confirm the synthesis of Fe3O4 nanoparticles and the preservation of the fibrous carbon structure. Electron microscopy shows that C-BCLP has a highly porous and conductive network with a homogeneous distribution of C, O, N, S, and Fe elements. Because of the combined effects of hierarchical porosity, heteroatom doping, and Fe3O4 incorporation, the C-BCLP electrode has high specific capacitances of 338.3 F g–1 at 1 A g–1 and 191.6 F g–1 at 10 A g–1. In addition, it has excellent cycling stability, retaining 99.1% of its initial capacitance after 10,000 charge-discharge cycles, outperforming the C-BCP electrode. The work suggests a promising way to develop next-generation high-performance supercapacitors.