Metallic and Magnetic 2D Materials Containing Planar Tetracoordinated C and N

Abstract

ABSTRACT:The top monolayers of surface carbides and nitrides of Co and Ni are predicted to yield new stable 2D materials upon exfoliation. These 2D phases are p4g clock reconstructed, and contain planar tetracoordinated C or N. The stability of these flat carbides and nitrides is high, and ab initio molecular dynamics at a simulation temperature of 1800 K suggest that the materials are thermally stable at elevated temperatures. The materials owe their stability to local triple aromaticity (π, σ-radial, and σ-peripheral) associated with binding of the main group element to the metal. All predicted 2D phases are conductors, and the two alloys of Co are also ferromagnetic, a property especially rare among 2D materials. The preparation of 2D carbides and nitrides is envisioned to be done through surface deposition and peeling, possibly on a metal with a larger lattice constant for reduced affinity.

Oxidative Dehydrogenation of Cyclohexane by Cu vs Pd Clusters: Selectivity Control by Specific Cluster Dynamics

“…Small supported clusters are unique and puzzling catalysts: their properties are strongly size‐, composition‐, and support‐sensitive . Recently, we have noted that such catalysts present a variety of structures that easily interconvert at catalytic temperatures, thus collectively defining the properties of the catalyst . Here, we present a set of subnanometer Pd and Cu cluster catalysts that exhibit very different and highly competitive selectivities for oxidative dehydrogenation (ODH) of cyclohexane .…”

“…[1][2][3][4][5][6][7][8][9][10] Recently, we have noted that such catalysts present a variety of structures that easily interconvert at catalytic temperatures, thus collectively defining the properties of the catalyst. [10][11][12][13][14][15][16][17] Here, we present a set of subnanometer Pd and Cu cluster catalysts that exhibit very different and highly competitive selectivities for oxidative dehydrogenation (ODH) of cyclohexane. [2,[18][19][20][21][22][23] We show that the observed differences in the catalysts' performance are ultimately linked to both structural and redox evolution within the evolving ensembles of thermally accessible catalyst states under applied reaction conditions.…”