In situ modification of metal electrode by integrated microbial corrosion and microbial mineralization using Shewanella oneidensis for efficient oxygen evolution

The modification of a metal electrode with catalytic nanoparticles is considered as a promising approach to fabricate electrodes for efficient oxygen evolution reaction (OER) electrocatalysis. However, the synthesis of catalytic nanoparticles and the modification onto the metal electrode usually involve a sophisticated fabrication process with toxic chemicals and high energy consumption. Herein, by integrating the microbial corrosion of the metal electrode surface with the biomineralization of transition-metal sulfides by Shewanella oneidensis MR-1, a bacterial cell-based green approach for the in situ modification of metal electrodes was developed. S. oneidensis MR-1 cells not only acted as an efficient reducing agent to synthesize metal sulfides but also served as an oxidizing agent to synthesize metal hydroxides on the surface of nickel foam. The synergistic effect between metal sulfides and hydroxides enabled bio-modified nickel foam as an efficient OER electrode. Among the studied NF supported transition-metal sulfides (MSx: M = Fe, Ni, Cu, Cd), ferric sulfide showed the highest OER activity. By adjusting the S/Fe ratio in the precursor, the charge transfer capability at the catalyst–electrolyte interface was optimized, and the Fe–S20/NF electrode exhibited excellent OER activity with an overpotential of 0.253 V at a current density of 10 mA cm−2. This work provides a green and scalable method for the in situ modification of metal electrode with low energy consumption, which would be promising for the practical and large-scale fabrication of electrodes for efficient OER.