Atomically dispersed Pd catalysts in graphyne nanopore: formation and reactivity

Abstract

The formation of single-atom noble metal catalysts on carbon materials remains a challenge due to the weak interaction between metals and pristine carbon. By means of density functional theory (DFT) calculations, it is found that the atomically dispersed Pd in graphyne nanopore is much more stable than that of relative Pd clusters. The large diffusion barrier of Pd from the most stable hollow site to the bridge site confirms the kinetic stability of such structures. While CO adsorption causes the pulling of Pd from graphyne nanopore due to the low diffusion barrier, based on DFT calculations, which can be further confirmed by ab initio molecular dynamic simulations. Finally, CO oxidation on the reconstruction of Pd@graphyne exhibits an energy barrier of 0.62 eV in the rate-limiting step through the Langmuir-Hinshelwood mechanism. After the reaction, the catalyst can be restored to the original atomically dispersed state again. This study shows graphyne is an excellent support for an atomically dispersed or single-metal catalyst.

Mechanistic Insights into Direct Methane Oxidation to Methanol on Single-Atom Transition-Metal-Modified Graphyne

“…It has been proved that the geometrical and chemical nature of the acetylenic ring is highly suitable for stabilizing single metal atoms. 47,50 The single metal atoms are six-coordinated with sp-hybridized carbon atoms in the acetylenic ring with average metal−carbon distances for Fe, Co, Ni, and Cu of 1.97, 1.95, 1.96, and 2.05 Å, respectively. The significantly negative binding energies of Fe, Co, Ni, and Cu (−3.87, −4.19, −4.79, −2.80 eV) on GY suggest that these atoms are tightly bound to the acetylenic ring (Figure 1b).…”

Multiscale simulation on thermal stability of supported metal nanocatalysts

“…The simulation results show that the thermal stability of the Pt 2 Pd is more influenced by nanopores, though the nitrogen can slightly enhance the adsorption energy . To overcome the weak MSI‐induced thermal instability, atomically dispersed Pd in graphyne nanopore is designed and shows higher adsorption energy than corresponding Pd clusters . Recently, Wang and coworkers studied the stability of single Ru atom embedded in C 2 N, T‐C 3 N 4 , and γ‐graphynes with the help of DFT calculation and AIMD simulations, which followed the order of Ru 1 @C 2 N > Ru 1 @T‐C 3 N 4 > Ru 1 @γ‐graphynes.…”

Pd Clusters on Schiff Base–Imidazole-Functionalized MOFs for Highly Efficient Catalytic Suzuki Coupling Reactions

“…However, because of high surface energy, a too tiny size could lead to aggregation and particle growth ( Tang et al, 2017 ; Si et al, 2018 ; Xin et al, 2018 ). A solution to the critical issue is to apply a nanoporous supporting material, such as graphene ( Gu et al, 2017 ; Liu et al, 2019 ), carbon nanofibers ( Eid et al, 2019 ), C 3 N 4 ( Yang et al, 2021 ; Zhang et al, 2021 ), and porous SiO 2 ( Peng et al, 2019 ). Nevertheless, some disadvantages, such as leaching and aggregation of SNMCs, exist during the catalytic process by using these materials as support, which, thus, weaken the catalytic activity ( Gu et al, 2017 ; Liu et al, 2019 ; Zhang et al, 2021 ).…”

“…A solution to the critical issue is to apply a nanoporous supporting material, such as graphene ( Gu et al, 2017 ; Liu et al, 2019 ), carbon nanofibers ( Eid et al, 2019 ), C 3 N 4 ( Yang et al, 2021 ; Zhang et al, 2021 ), and porous SiO 2 ( Peng et al, 2019 ). Nevertheless, some disadvantages, such as leaching and aggregation of SNMCs, exist during the catalytic process by using these materials as support, which, thus, weaken the catalytic activity ( Gu et al, 2017 ; Liu et al, 2019 ; Zhang et al, 2021 ). Therefore, it is of great importance to design supporting materials that cannot only make ultrafine SNMCs with uniformity and high dispersion but also endow the obtained catalysts with excellent catalytic activity.…”