Nanorods of cerium oxide as an improved electrocatalyst for enhanced oxygen reduction in single-chambered microbial biofuel cells

This paper reports the synthesis and utilization of cerium oxide (CeO₂) nanorods as a cathode catalyst and a potential, low-cost replacement of platinum for microbial biofuel cells (MBFCs). The nanorod electrocatalyst had exhibited significant improvements over Pt nanoparticles in terms of forward and backward onset potentials and peak current densities, electronic conductivity, charge transfer resistance, stability in 0.1 M phosphate buffer solution, and cost. It had also demonstrated a more stable forward peak current density at the 100th steady cycle, as well as, higher current density values up to 7,200 s. In addition, the synthesized CeO₂ nanorods also produced ∼10³ times higher exchange current density over the synthesized Pt nanoparticles. Furthermore, in a single-chamber MBFC, the CeO₂ nanorods exhibited higher open circuit voltage (+0.80 V after 14 days), and output current (3613 mAm^-2 at +0.3 V) and power (1084 mWm^-2) densities in comparison to Pt nanoparticles.