Revealing Co-N₄ @Co-NP Bridge-Enabled Fast Charge Transfer and Active Intracellular Methanogenesis in Bio-Electrochemical CO₂ -Conversion with Methanosarcina Barkeri.

Abstract

To significantly advance the bio-electrochemical CO₂ -conversion rate and unfold the correlation between the abiotic electrode and the attached microorganisms, an atomic-nanoparticle bridge of Co-N₄ @Co-NP crafted in metal-organic frameworks-derived nanosheets is integrated with a model methanogen of Methanosarcina barkeri (M. barkeri). The direct bonding of N in Co-N₄ and Fe in member protein of Cytochrome b (Cytb) activates a fast direct electron transfer path while the Co nanoparticles further strengthen this bonding via decreasing the energy gap between the p-band center of N and the d-band center of Fe. This multiorbital tuning operation of Co nanoparticles also enhances the coenzyme F420-mediated electron transfer by enabling the electron flow direct to the hydrogenation sites. Particularly, the increased surface electric field of the Co-N₄ @Co-NP bridge-based nanosheet electrode facilitates the interfacial Na⁺ accumulation to expedite ATPase transport for powering intracellular CO₂ conversion. Remarkably, the self-assembled M.barkeri-Co-N₄ @Co-NP biohybrid achieves a high methane production rate of 3860 mmol m^-2 day^-1 , which greatly outperforms other reported biohybrid systems. This work demonstrates a comprehensive scrutinization of biotic-abiotic energy transfer, which may serve as a guiding principle for efficient bio-electrochemical system design.