安価な青色顔料触媒でCO2をガス燃料メタンに高効率変換する手法を実現 ―CO2のワンステップでの再燃料化技術に道―

2026-08-04 東北大学

図1. 銅フタロシアニンを担持したカーボンの模式図（左図）とCO₂→CH₄変換の触媒性能（右図、最大電流密度と最大ファラデー効率）。

＜関連情報＞

• https://www.tohoku.ac.jp/japanese/2026/08/press20260804-03-co2.html
• https://onlinelibrary.wiley.com/doi/full/10.1002/smll.75041

電気触媒的CO₂メタン化におけるCu–N–C分子触媒の構造依存的性能の解明 Unraveling Structure-Dependent Performance of Cu–N–C Molecular Catalysts for Electrocatalytic CO2 Methanation

Tengyi Liu, Xiaofan Hou, Songbo Ye, Kosuke Ishibashi, Yutaro Hirai, Yasutaka Matsuo, Shimpei Ono, Hao Li, Hiroshi Yabu
Small  Published: 02 August 2026
DOI:https://doi.org/10.1002/smll.75041

ABSTRACT

High-rate CH₄ electrosynthesis offers a promising strategy for converting CO₂ into energy-dense fuels compatible with existing natural gas infrastructure. Cu–N–C molecular catalysts with well-defined Cu–N₄ sites show strong potential for CO₂-to-CH₄ production, yet the role of the macrocyclic backbone remains unclear. Herein, we compare two representative Cu–N–C molecular catalysts, copper phthalocyanine (CuPc) and copper tetraphenylporphyrin (CuPr), to clarify how the macrocyclic backbone influences CO₂-to-CH₄ electrocatalysis. When supported on conductive carbon and integrated into gas-diffusion electrodes, CuPc markedly outperforms CuPr, achieving a CH₄ Faradaic efficiency of 79.5%, a high partial current density of −575 mA cm⁻², a mass activity of 19 166.7 A g⁻¹, and stable operation for over 80 h at −150 mA cm⁻². Characterization results suggest that the Pc-macrocyclic backbone modulates the electronic structure of the Cu center and interfacial charge-transfer behavior, possibly through its extended π-conjugated Pc-ring and bridge-N environment. Theoretical calculations reveal a favorable CH₄-forming pathway on the CuPc/C model, with a lower free-energy barrier for the potential-determining step than that reported for CuPr, suggesting facilitated CH₄ formation. These findings indicate that the macrocyclic backbone can regulate reaction pathways and intermediate adsorption energetics, providing mechanistic insight and design guidance for molecular catalysts for CO₂-to-CH₄ electroreduction.