Micro/Nanostructured Multivalent Iron Carbonaceous Ensembles Amplified the Methanogenesis of Syntrophic Microbial Cells

Converting organic wastes into clean energy is vital to the development of sustainable urban and zero/low-carbon communities but is challenging to achieve because of inefficient electron flux between acidogens and methanogens. Inspired by the unique electron configuration of Fe–S clusters in ferredoxin and their electron–proton transfer function in methanogenesis, we designed biologically adaptive micro/nanostructured multivalent iron carbon ensembles (mNICE) as cell synthesis accelerators, in which the high-spin Fe(III) sites would serve as biomimetic biological centers to directionally activate the key enzymes of methanogenesis. Upon successfully constructing mNICE-oriented real syntrophic microbial consortia, mNICE were found to dynamically buffer the acidogenic electrons and establish a directional electron transport chain between acidogens and methanogens. These roles subsequently synchronized proton flux via accelerating the regeneration of F420H2 and CoM–SH/CoB–SH via activating the critical F420 hydrogenase and heterodisulfide reductase. Such biotic-abiotic interfacial interactions between mNICE and syntrophic multicellular communities sustained organic-loading rates via improving the degradation of volatile fatty acids and retarding their toxicity to methanogens. As a result, mNICE elevated the methane yield by 134.20%. This work highlights the importance of steering the activity of key enzymes across the cell-material interface in the development of sustainable waste-to-energy conversion systems.