Taming Biotic-Abiotic Interface with Atomic Defects for Efficient Hydrogen Production from Wastewater

Sluggish interfacial kinetics at the bio-abiotic junction fundamentally bottleneck the efficiency of microbial electrochemical hydrogen production from wastewater, as electronic barriers and rigid water networks obstruct the seamless transport of electrons and protons. We surmount these synergistic challenges by coupling Shewanella oneidensis MR-1 with vacancy-engineered pyrite (FeS2), achieving an impressive H2 evolution rate of 1.92 mmol h-1 with high operational stability (100 h at 60 mA cm-2). In situ spectroscopy and molecular dynamics (MD) simulations suggest that under-coordinated Fe sites associated with sulfur vacancies facilitate electron transfer through coordination-assisted interactions with microbial cytochromes, while localized charge polarization disrupts the ordered four-coordinate water network to facilitate interfacial proton transfer. A solar-powered prototype treating authentic food waste leachate demonstrates a 4.7% solar-to-hydrogen efficiency. Life-cycle and techno-economic analyses confirm the system's sustainability, yielding a net profit of \$0.70 per ton of wastewater and a minimized carbon emissions potential of 0.33 kg CO2 equivalent. This work establishes vacancy-enabled biotic-abiotic interface engineering as a transformative strategy for optimizing interfacial microenvironments in high-performance noble-metal-free bio-electrochemical energy recovery.