Boosting the electrocatalytic activity of Desulfovibrio paquesii biocathodes with magnetite nanoparticles

The production of reduced value-added chemicals and fuels using microorganisms as cheap cathodic electrocatalysts is recently attracting considerable attention. A robust and sustainable production is, however, still greatly hampered by a poor understanding of electron transfer mechanisms to microorganisms and the lack of strategies to improve and manipulate thereof. Here, we investigated the use of electrically-conductive magnetite (Fe ₃O₄) nanoparticles to improve the electrocatalytic activity of a H₂-producing Desulfovibrio paquesii biocathode. Microbial biocathodes supplemented with a suspension of nanoparticles displayed increased H₂ production rates and enhanced stability compared to unamended ones. Cyclic voltammetry confirmed that Faradaic currents involved in microbially-catalyzed H₂ evolution were enhanced by the addition of the nanoparticles. Possibly, nanoparticles improve the extracellular electron path to the microorganisms by creating composite networks comprising of mineral particles and microbial cells.