Microbial Pyrolysis for the Sustainable Synthesis of Nanoparticle-Embedded Carbon Electrocatalysts

Electrocatalytic processes are essential for a sustainable global economy, yet conventional catalyst synthesis often relies on hazardous reagents and insulating binders that impede performance. Here, microbial extracellular electron transfer for nanoparticle synthesis is integrated with the controlled pyrolysis of microbial monolayers to generate nanoparticle-embedded carbon electrodes. Surface immobilization of Shewanella oneidensis using DNA "Velcro" yields uniform single-microbe-thick layers that are readily patterned and converted into conductive, turbostratic carbon films at temperatures between 800 °C and 1,100 °C. These bio-derived films exhibit progressive graphitic ordering and reach a minimum sheet resistance of 1.49 kΩ/sq, approaching the performance of pyrolyzed synthetic photoresists. Moreover, by leveraging the intrinsic biosynthetic capabilities of S. oneidensis, 3-5 nm palladium nanoparticles are formed directly on the cell surface and seamlessly integrated into the carbon matrix upon pyrolysis. These composites reduce the hydrogen evolution reaction overpotential by 100 mV. This bottom-up bioengineering approach is anticipated to enable the sustainable, programmable fabrication of next-generation electrocatalysts for diverse energy conversion applications.