Support effects on adsorption and catalytic activation of O₂ in single atom iron catalysts with graphene-based substrates

Abstract

The adsorption and catalytic activation of O on single atom iron catalysts with graphene-based substrates were investigated systematically by density functional theory calculation. It is found that the support effects of graphene-based substrates have a significant influence on the stability of the single atom catalysts, the adsorption configuration, the electron transfer mechanism, the adsorption energy and the energy barrier. The differences in the stable adsorption configuration of O on single atom iron catalysts with different graphene-based substrates can be well understood by the symmetrical matching principle based on frontier molecular orbital analysis. There are two different mechanisms of electron transfer, in which the Fe atom acts as the electron donor in single vacancy graphene-based substrates while the Fe atom mainly acts as the bridge for electron transfer in double vacancy graphene-based substrates. The Fermi softness and work function are good descriptors of the adsorption energy and they can well reveal the relationship between electronic structure and adsorption energy. This single atom iron catalyst with single vacancy graphene modified by three nitrogen atoms is a promising non-noble metal single atom catalyst in the adsorption and catalytic oxidation of O. Furthermore, the findings can lay the foundation for the further study of graphene-based support effects and provide a guideline for the development and design of new non-noble-metal single atom catalysts.

Bridging the Homogeneous-Heterogeneous Divide: Modeling Spin for Reactivity in Single Atom Catalysis

“…The fundamental source of this spin-state dependent reactivity remains unknown. In SAC electrocatalysts (Fei et al, 2015; Qiu et al, 2015; Zitolo et al, 2015, 2017; Back et al, 2017; Chen et al, 2017; Cheng et al, 2017; Zhang et al, 2017a,b; Zhu et al, 2017; Gao et al, 2018; Jiang et al, 2018; Wang et al, 2018; Zhang et al, 2018), changes in applied potential (e.g., in ORR) have been suggested to change the Fe SAC active site, possibly through a change in spin state (Zitolo et al, 2017).…”

Reinvestigating oxygen adsorption on Ag(111) by using strongly constrained and appropriately normed semi-local density functional with the revised Vydrov van Voorhis van der Waals force correction

“…At the H site, the O2 molecule was above the surface at the fcc site.The molecular oxygen adsorption properties varied at the adsorption sites. The O-O bond lengths are listed in Table2because the bond distance is an important indicator of bond strength55 . The SCAN-rVV10 results reveal that two O atoms were 1 48.…”

Ultralow Overpotential of Hydrogen Evolution Reaction using Fe‐Doped Defective Graphene: A Density Functional Study

“…To understand the origin of the hydrogen adsorption energies and HER activity of the present SACs, we considered the d band center, the lowest unoccupied state energy (E lus ), and the ionic energy (E ionic ) ,. The ionic energy E ionic was calculated by the work function of the SACs (E ionic =Δq ⋅ ΔΦ=Δq ⋅ (Φ SAC −Φ H ); Δq: charge transfer, Φ: workfunction),, an approximate measure of charge transfer between SACs and adsorbed hydrogen atom . As shown in Figure , we find no linear correlation between the calculated hydrogen adsorption energies on SACs vs. d band center (as in literature) or lowest unoccupied state energy.…”

“…As shown in Figure , we find no linear correlation between the calculated hydrogen adsorption energies on SACs vs. d band center (as in literature) or lowest unoccupied state energy. The ionic energy, however, shows a significantly improved linear relationship with the H adsorption energy of the SACs . This result indicates that ionic binding character (charge transfer from SACs to hydrogen atom) is a better descriptor than covalent binding character (d band center or lowest unoccupied state energy) for SACs in describing the HER catalytic activity.…”