生体触媒による排ガスおよび大気レベル低濃度CO₂の資源化―酸化還元酵素の卓越した機能を利用した脱炭素技術の実現―

2026-08-24 京都大学

FoDH1によるガス状CO₂からギ酸への資源化　©️京都大学（イラストレーター：田中花音）

＜関連情報＞

• https://www.kyoto-u.ac.jp/ja/research-news/2026-08-24
• https://pubs.acs.org/acsodf/article/11/32/47701/5239816/Direct-Electron-Transfer-Type-Gas-Diffusion

低濃度CO2条件下での効率的なCO2/ギ酸変換に向けた直接電⼦移動型ガス拡散型電極の構築 Direct Electron Transfer-Type Gas Diffusion Electrode for Efficient CO2-to-Formate Bioconversion across Broad and Low CO2 Levels

Ami Kobayashi;Taiki Adachi;Konatsu Ichikawa;Yuki Kitazumi;Osamu Shirai;Keisei Sowa

ACS Omega  Published:August 03, 2026

DOI:https://doi.org/10.1021/acsomega.6c02909

Abstract

Bioelectrocatalytic CO₂ reduction to value-added chemicals offers a sustainable route for carbon recycling; however, achieving high activity under low CO₂ conditions remains a major challenge. Herein, we report a direct electron transfer (DET)-type gas diffusion electrode (GDE) utilizing formate dehydrogenase 1 (FoDH1) from Methylorubrum extorquens AM1 for efficient CO₂-to-formate conversion across a broad range of low CO₂ levels. The electrode surface was modified with pyrene derivatives using multiwalled carbon nanotubes (MWCNTs) to tailor the enzyme–electrode interface, enabling favorable enzyme orientation for rapid electron transfer. A 1-pyrenemethylamine (PyNH₂)-modified GDE with FoDH1 exhibited a current density of −1.2 mA cm^–2 at a reduction potential of −0.9 V, which was twice that of the pristine electrode, and generated formate with a Faradaic efficiency of 82 ± 5%, outperforming previously reported GDE systems. Kinetic analyses under controlled CO₂ conditions (0.04–100%) revealed a notably low apparent Michaelis constant (K_M,app) of 2.6 ± 0.3%, which is less than one-third of that of the solution system, indicating high CO₂ affinity. This enhancement is attributed to the direct supply of gaseous CO₂ to the catalytic layer, avoiding equilibrium limitations in the electrolyte solution. These results lead to a promising tool for enzymatic CO₂ reduction using emission gases from industrial sources and provide key design principles for practical CO₂-recycling technologies.