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Directly converting syngas to α-olefins via the Fischer-Tropsch synthesis reaction serves as a competitive alternative to the traditional petroleum route, which has attracted much recent attention. However, achieving high catalytic activity over the iron-based catalyst remains a grand challenge, due to the easy oxidation of the iron carbides active phase by the water produced during reaction. Herein, we present a porous graphite-carbon encapsulated iron-based catalyst, in which the iron carbides remain stable even under harsh reaction conditions of high CO conversion or high reaction temperature. Due to the excellent anti-oxidation ability of active phase, an ultrahigh activity for producing C 4+ α-olefins of 11.35 g·g cat −1·h−1 can be obtained. This work provides a promising strategy to develop iron-based Fischer-Tropsch synthesis catalysts with high catalytic activity and stability by rationally stabilizing iron carbides. [Display omitted] • A strategy to stabilize iron carbides during syngas to α-olefins was proposed. • Porous graphite-carbon encapsulated pure iron carbides was successfully prepared. • The rigid graphite-carbon protected iron carbides from oxidation by water. • Ultrahigh activity for producing C 4+ α-olefins of 11.35 g·g cat −1·h−1 was achieved. [ABSTRACT FROM AUTHOR]

The intrinsic activity of single-atom catalysts is influenced by the local electronic structures of metal centers, with existing modulation strategies limited to adjacent atomic coordination. However, the impacts of support surface geometry on local bonding environment, and thus electronic structures of single-atom centers have rarely been known. Here, we prepared highly curved B,N co-doped carbon-supported ruthenium catalyst with an ultra-low Ru loading of 0.4 wt%, which exhibited an ultrahigh turnover frequency (TOF) of 10 H 2 s−1 (38 times that of Pt/C) and superior stability in alkaline hydrogen evolution reaction (HER). We found that curving support surface induced the strain, resulting in 1.5% compressed Ru-N and 4% stretched Ru-B bonds, leading to the accumulation of positive charge and quenching of spin polarization at Ru sites, thereby achieving the optimal binding of H* and enhanced performance for HER. This work highlights the significant support effects upon the structural design of active sites. [Display omitted] • Two types of B, N co-doped carbon-supported Ru site catalysts with and without support surface curvature were synthesized. • Curving the support surface induces strain and thereby changes the local bond length at the Ru sites. • Regulating bond length increases the aggregation of positive charges and suppresses spin polarization at the Ru sites. • The B, N co-doped carbon-supported Ru site catalyst with curvature achieves optimal H* binding strength for HER. • The turnover frequency of Ru sites with curvature is significantly higher than those without surface curvature. [ABSTRACT FROM AUTHOR]