Electrophoretically fabricated nickel/nickel oxides as cost effective nanocatalysts for the oxygen reduction reaction in air-cathode microbial fuel cell

The high cost and limited availability of cathode catalyst materials (most commonly Pt) prevent the large-scale practical application of microbial fuel cells (MFCs). In this study, unique Pt group metal-free (PGM-free) nanocatalysts were fabricated using a simple and cost-effective technique called electrophoretic deposition (EPD) to create a high catalytic oxygen reduction reaction rate (ORR) on the cathode surface of MFCs. Among the tested PGM-free catalysts (Ni, Co, and Cd-based), a maximum power density of 1630.7 mW m⁻² was achieved based on nickel nanoparticles. This value was 400% greater than that obtained using a commercial Pt catalyst under the same conditions. This result was due to the uniform deposition of a thin layer of Ni/NiO_x nanoparticles on the cathode, which improved electrical conductivity, catalytic activity, and long-term stability while reducing electron transfer resistance. The fabricated PGM-free catalysts significantly improved MFC performance and accelerated ORR induced by the novel layered morphology of metal/metal oxide nanoparticles.