Non-precious HfO2 nanoparticle as an alternative cathode catalyst for microbial fuel cell applications

Abstract

This study evaluated hafnium oxide (HfO2) as a cathode catalyst material in air-cathode single-chamber microbial fuel cells (SCMFCs). Various HfO2 crystalline phases, synthesized via a precipitation method under specific temperature conditions, were examined for electrochemical performance in MFCs, including voltage, power generation, cyclic voltammetry, and impedance spectroscopy. The MFC-600 °C variant outperformance MFC-500 °C and MFC-700 °C yielding power density of 1152 ± 9 mW m−2 and voltage 284 ± 8 mV. In a double loading (DL) configuration (1 mg cm−2), MFC-600 °C exhibited higher power density than single loading and triple loading. The MFC-600 °C DL electrode showed up to 57.3% of the performance of the traditional Pt/C cathode (2009 ± 12 mW m−2). On the other hand, when considering catalyst loading, the 10% Pt/C (0.5 mg cm−1) had a lower power density than the HfO2 600 °C DL (1 mg cm−1): 4.018 mW m−2 g−1 vs. 11.52 mW m−2 g−1. These findings highlight the promising viability of the HfO2 cathode as an economically advantageous catalyst material for MFCs, potentially paving the way for commercialization.