Defect Engineering in Graphene-Confined Single-Atom Iron Catalysts for Room-Temperature Methane Conversion

Xin Tan*, Hassan A. Tahini, Sean C. Smith*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    28 Citations (Scopus)

    Abstract

    Direct conversion of methane to high-value-added chemicals with oxidants, such as H2O2, O2, and so forth, without going through the intermediate syngas production step is potentially more energy efficient, cost-effective and environmentally friendly. Recent experiments have demonstrated that graphene-confined single-atom Fe (FeN4) catalysts could efficiently catalyze direct methane conversion to C1 oxygenates at room temperature. However, the methane conversion rates of FeN4catalysts are far from satisfactory. Motivated by the enormous potential of defect engineering to advance rational catalyst design, we carry out first-principle computations to systematically explore the impact of various defects, including vacancies and substitutional doping of heteroatoms, on the catalytic activities of FeN4catalysts for the direct conversion of methane to C1 oxygenates. Encouragingly, we find the C vacancies (FeN4-V6rand FeN4-V5r) and P dopant (P-O/FeN4) adjacent to FeN4centers can significantly improve the methane conversion activities of FeN4catalysts. Our results show that the methane activation rates of FeN4-V6r, FeN4-V5r, and P-O/FeN4are 1.7 × 104, 2.4 × 103, and 5.3 × 103times higher than that of perfect FeN4catalyst, respectively. The improved catalytic performance of these three FeN4catalysts stem from their moderate formation energy of O-FeN4-O active site (Gf), which is used as a key descriptor for characterization of methane conversion activity. This study brings new understanding of the potential impact of controlled defect engineering on direct methane conversion using FeN4catalysts, revealing a promising avenue to boost the catalytic performance for room-temperature methane conversion.

    Original languageEnglish
    Pages (from-to)12628-12635
    Number of pages8
    JournalJournal of Physical Chemistry C
    Volume125
    Issue number23
    DOIs
    Publication statusPublished - 17 Jun 2021

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