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

• Published in: Joule Vol. 4; no. 4; pp. 800 - 811
• Main Authors: Su, Yude, Cestellos-Blanco, Stefano, Kim, Ji Min, Shen, Yue-xiao, Kong, Qiao, Lu, Dylan, Liu, Chong, Zhang, Hao, Cao, Yuhong, Yang, Peidong
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.04.2020
• Subjects: biocatalysis; bioelectrochemistry; bioinorganic hybrids; carbon dioxide fixation; nanoscience; nanowire; solar energy conversion; solar energy conversion; bioelectrochemistry; nanoscience; bioinorganic hybrids; biocatalysis; carbon dioxide fixation; nanowire
• ISSN: 2542-4351; 2542-4351
• DOI: 10.1016/j.joule.2020.03.001

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. [Display omitted] •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 Bioinorganic interface is a key determinant for microbial catalytic CO2 fixation. However, the correlation between bioinorganic interface and CO2-conversion efficiency has not been systematically studied as a function of operational parameters. Here, investigation of the microorganism-cathode interface allowed us to boost the CO2-reducing rate in a silicon nanowire/Sporomusa ovata system. We found that the CO2-reducing rate at high potential was limited by poor bacteria-nanowire interface resulting from an inhospitable alkaline local environment. Tuning the bulk electrolyte pH and increasing its buffering capacity mitigated this issue and facilitated the formation of a close-packed nanowire-bacteria cathode. The resulting close-packed biohybrid achieved a CO2-reducing current density of 0.65 ± 0.11 mA cm−2. Our system enabled solar-powered CO2 fixation with solar-to-acetate efficiency of ∼3.6% over 1 week. Bioelectrochemical CO2-reducing rate at high potential was limited by poor bacteria-nanowire interface resulting from an inhospitable alkaline local environment. Tuning the bulk electrolyte pH and increasing its buffering capacity mitigated this issue and supported the formation of a close-packed nanowire-bacteria cathode. The resulting close-packed biohybrid operated with a CO2-reducing current density of 0.65 ± 0.11 mA cm−2 at ∼−1.2 V versus standard hydrogen electrode and enabled solar-powered CO2 fixation with solar-to-acetate efficiency of ∼3.6% over 1 week.