Effect of heat-treatment atmosphere on the current generation of TiO2 nanotube array electrodes in microbial fuel cells

We investigated the effects of the heat-treatment atmosphere on the current generation of Ti electrodes in microbial fuel cells (MFCs). The maximum current density was achieved for TiO2 nanotube array electrodes heated in H2 (TNA-H2) (22.69 ± 0.18 A m−2). Physical analysis of the Ti electrode surfaces revealed that the specific surface area increased after electrochemical anodization. The crystallinities of the TiO2 nanotube array electrodes heated in H2 (81.66%), CH4 (74.48%), N2 (59.67%), and O2 (44.82%) showed a significant positive correlation with the corresponding current densities (P < 0.05, R2 = 0.9469). In addition, the highest electron transfer rate constant was achieved for TNA-H2 (2.38 s−1). The large specific surface area, good chemical stability, high electron transfer rate, and good biocompatibility of TNA-H2 suggest its great potential for application as an anode system in MFCs.