Close-Packed Nanowire-Bacteria Hybrids for Efficient Solar-Driven CO₂ Fixation

Highlights

• Close-packed bacteria-nanowire hybrids achieved

• Microbial CO₂-reducing current density boosted to 0.65 mA cm⁻²

• COMSOL simulation explains the nanowire-cell interactions under different pH conditions

• A 3.6% solar-to-acetate efficiency realized over 1 week

Summary

Microbial electro- and photo-electrochemical CO₂ fixation, in which CO₂-reducing microorganisms are directly interfaced with a cathode material, represent promising approaches for sustainable fuel production. Although considerable efforts have been invested to optimize microorganism species and electrode materials, the microorganism-cathode interface has not been systematically studied. Here, investigation of the interface allowed us to optimize the CO₂-reducing rate of silicon nanowire/Sporomusa ovata system. Tuning the bulk electrolyte pH and increasing its buffering capacity supported the formation of a close-packed nanowire-bacteria cathode. Consequently, the resulting close-packed biohybrid achieved a CO₂-reducing current density of ∼0.65 mA cm⁻². When coupled with a photovoltaic device, our system enabled solar-to-acetate production with ∼3.6% efficiency over 7 days.