Engineered nickel foam dual-function electrode optimised electron transfer and biohydrogen evolution in single chambers microbial electrolysis cells

Abstract

The widespread deployment of microbial electrolysis cells (MECs) for sustainable H 2 production is critically hindered by the reliance on costly platinum-based electrodes. Herein, we develop a ferric oxyhydroxide-intercalated cobalt phosphide composite supported on nickel foam (FeOOH-CoP/NF) as a durable, non-precious bifunctional electrode for MECs. The engineered heterostructure exhibits remarkable electrocatalytic activity toward the hydrogen evolution reaction (HER: 189 mV at 10 mA cm −2 , Tafel 105 mV dec −1 ) and oxygen evolution reaction (OER: 284 mV at 10 mA cm −2 , Tafel 47 mV dec −1 ), with robust stability over 200 h. When deployed symmetrically as both anode and cathode in single-chamber MECs treating sewage sludge, the FeOOH-CoP/NF electrodes achieve a sustained average HPR of 0.448 m 3 m −3 d −1 and (η_E) of 158% at 0.8 V. High-throughput sequencing reveals a functionally synergistic biofilm enriched in exoelectrogenic Proteobacteria ( Geobacter, Shewanella ) at the anode and in hydrogenogenic taxa at the cathode, comprising Firmicutes ( Clostridium ) together with Gammaproteobacteria ( Enterobacter ), consistent with efficient substrate oxidation and extracellular electron transfer. This work shows that FeOOH-CoP/NF is a posable cost-effective alternative to noble-metal catalysts, enabling high-rate H 2 production directly from complex waste streams and advancing MEC toward energy-positive wastewater treatment.