Multi-Walled Carbon Nanotube/Polyacrylamide Composite Hydrogels as Solid Electrolytes for Microbial Fuel Cells

Microbial fuel cells provide an economically and practically viable option for green generation of an electric power from an organic pollutants present in waste water with the help of micro-organisms. Several attempts are being made to commercialize the system for stable power generation. For portable applications, the size of the fuel cell and its volumetric power density are major determinants. In this context, microbial fuel cells with a solid electrolyte sandwiched between a cathode and anode would be an attractive configuration. In this work, the authors report the synthesis and characterization of highly cross-linked multi-walled carbon nanotube/polyacrylamide composite hydrogels as solid electrolyte for application in such devices. The composite hydrogels were synthesized by in situ free radical polymerization of an acrylarnide in presence of surfactant-dispersed multi-walled carbon nanotubes. An ionic conductivity was introduced to the hydrogels by partial hydrolysis in alkaline medium and the conductivity was compared using Electrochemical Impedance Spectroscopy. The composite hydrogels with different loadings of carbon nanotubes were characterized systematically by Differential Scanning Calorimetry, Scanning Electron Microscopy and Swelling studies.