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The Electronic Properties and CO Activation Mechanism of Fe atom Modulated by Graphene Confinement

LUO Dan1, WANG Jianxin1, LU Kuan2, WANG Min1, CHANG Tong1   

  1. 1. Shanxi Key Laboratory of Ecological Protection and Resources Utilization of Yuncheng Salt Lake, Department of Applied Chemistry, Yuncheng University 2. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences
  • Received:2025-10-15 Revised:2025-12-03 Online First:2025-12-08 Published:2025-12-08
  • Contact: Dan LUO E-mail:luodan@ycu.edu.cn
  • Supported by:

    Supported by the Applied Basic Research Program of Shanxi Province, China (Nos.202403021212036，202303021211188，202303021222243),the Basic Research Program of Yuncheng, China(No.YCKJ-2023049), the Reward Program for Coming to Shanxi, China(No.QZX-2023012) and the Yuncheng University Doctoral Research Launch Project, China(No.YQ2023025)

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Abstract: Using the density functional theory (DFT), the comprehensive and in-depth exploration was conducted into the structure, electronic properties, CO adsorption and activation performance of Fe atoms modulated by graphene confinement to reveal the influence of different coordination environment of Fe active centers on Fischer-Tropsch performance. The binding energies of Fe-doped single-atom defect graphene (FeC@graphene) and Fe-doped di-atom defect graphene are -7.49 eV and -6.50 eV, respectively, which indicates that FeC@graphene structure exhibits greater stability compared to the Fe2C@graphene. The DOS of FeC@graphene exhibits the more significant left-shift compared to Fe2C@graphene, with values of 1.5 eV and 0.8 eV respectively. The greater left-shift indicates that the FeC@graphene structure possesses lower energy, and the higher stability. The adsorption energies of CO on FeC@graphene and Fe2C@graphene are -1.43 eV and -1.69 eV, respectively, which reflects that CO adsorption on Fe2C@graphene is more stable than FeC@graphene. The d band center values of FeC@graphene and Fe2C@graphene are -1.26 eV and -0.83 eV, while their energy band gaps are 0.45 eV and 0.01 eV, respectively. The closer the d-band center is to the Fermi level, and the smaller the band gap, which is more conducive to the adsorption of species. Thus, compared with FeC@graphene, CO has a higher propensity to be adsorbed onto Fe2C@graphene. The band gap of Fe2C@graphene-CO increases by 0.25 eV, while FeC@graphene decreases by 0.04 eV; the antibonding component of FeC@graphene-CO is more than that Fe2C@graphene-CO, and the ICOHP values are -1.99 eV and -2.50 eV. These suggest that the interaction between Fe2C@graphene and CO is stronger, while strong interaction is unfavorable for CO activation. On the FeC@graphene and Fe2C@graphene, the most favorable pathway for CO activation follows the sequence: CO* → CHO* → CH* + O*, with an effective energy barrier of 3.81 eV and 4.56 eV, respectively. It is easier for CO activation on FeC@graphene. Therefore, the three-coordination structure of the active center Fe is more stable and beneficial for enhancing FTS activity.

Key words: Defect graphene, Fe atom, Electronic property, CO adsorption and activity

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