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[Display omitted] • Real space evidence of p4g(2 × 2) Fe 2 C and Co 2 C surface carbides. • Tip-sample distance dependent STM imaging of Fe 2 C. • Fe 2 X (X = B, C, N, O) with increasing electrons the reconstruction becomes less favourable. Thin FCC (1 0 0) iron and cobalt carbide films were prepared on Cu(1 0 0) to study the connection between their structure, electronic properties and stability. We present the first detailed, real space experimental confirmation of the C-induced clock reconstruction on the FCC(1 0 0) surfaces of iron and cobalt. Both Fe and Co surface carbides show p4g (2 × 2) surface reconstruction with tetracoordinated square planar carbon and pure FCC (1 0 0) metal layers underneath. Combining tip-sample distance dependent STM imaging with theoretical calculations we present different imaging modes of Fe 2 C. Using a combination of angle-resolved x-ray photoelectron spectroscopy (AR-XPS), Auger electron spectroscopy (AES), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and theoretical calculations we provide detailed electronic and structural models for Fe 2 C and Co 2 C p4g (2 × 2) surface carbides and other 2D Fe 2 X interstitial compound systems. In various Fe 2 X (X = B, C, N, O) surface compounds moving to the right in the periodic table with increasing electrons the reconstruction becomes less favorable, while iron carbide shows the highest stability. [ABSTRACT FROM AUTHOR]

Sn-containing Fe 5 C 2 interface not only can boost the rates of oxygen removal but also restrain the coke deposition by elevating the barrier of nucleation, which stabilizes the active iron carbide structure and enhanced the stability remarkablely. [Display omitted] • Oxygen removal by carbon oxide is facilitated for Fe-Sn interface； • Coking deposition was inhibited remarkably for Fe-Sn bimetallic catalysts; • Catalytic stability was significantly enhanced for Sn0.25 and Sn0.50 catalysts; • Provided a strategy to construct durable catalysts under the perspective of oxygen removal and coking resistance. Comprehending deactivation mechanisms and constructing durable Fe-based catalysts remain a substantial challenge for Fischer-Tropsch synthesis. In this contribution, the effects of Sn promoter on the structure and catalytic performance of Fe-based catalysts were investigated systematically. The catalytic stability was enhanced significantly for 100Fe/0.25Sn and 100Fe/0.50Sn catalysts, reducing the deactivation rate almost four-fold and seven-fold respectively. Combined with several characterizations and DFT calculation, it has been confirmed that Sn-containing Fe 5 C 2 interface not only can boost the rates of oxygen removal but also restrain the coke deposition by elevating the barrier of nucleation, which stabilizes the active iron carbide structure and inhibits the deactivation efficiently. This study may broaden the understanding of enhanced stability during Fe-based FTS under the perspective of oxygen removal and coking resistance and provide a strategy to construct durable catalysts. [ABSTRACT FROM AUTHOR]