Polyvinylidene fluoride effects on the electrocatalytic properties of air cathodes in microbial fuel cells

The use of polyvinylidene fluoride (PVDF) as a binder was investigated in order to prepare the active carbon catalyst and carbon black diffusion layers of a microbial fuel cell cathode. Compared with other binders, PVDF performed competitively as it did not require a lengthy curing time and high curing temperature. Results of XRD characterization showed that the typical β-PVDF was enhanced as PVDF content ratio increased. SEM results indicated that the catalyst layer easily peeled off due to the low binder concentration of binder, but the high binder content was deemed undesirable because the large amount of non-conductive PVDF interrupted the percolation path. The optimum binder concentration was double checked using Tafel and EIS tests. Results indicated that the cathode with 10% PVDF is the optimum operated concentration. The cathode can obtain 180mV of cathode potential and the smallest total impedance of 2500Ω, which are consistent with the SEM analysis. Moreover, the cathode with 10% PVDF concentration produced a maximum power density of 1600mWm^-2, suggesting that PVDF can compete with other traditional binders.