Room-Temperature Propylene Dehydrogenation and Linear Atomic Chain Formation on Ni(111)

Abstract

The structures formed by propylene adsorption on Ni(111) at room temperature are determined by a combination of scanning tunneling microscopy and density functional theory. As a result of the interaction with the Ni(111) surface, propylene molecules are dehydrogenated and coupled into linear hydrocarbon chains. The length of the chains varies from 8 to 60Å, with the most frequently observed length of 18Å. At saturated coverage, some chains are closed in rings with a diameter of 6Å. The chains C12H12 (four C3H3 fragments), linear and closed, best fit the observed structures. We demonstrate that the possibility of combining initial propylene molecules into chains appears after dehydrogenation of the CH3 fragment.

Activation, Transportation, and Reaction of Alkyl Radicals on a Si(111)-B Surface by a Scanning Tunneling Microscope Tip

“…To fully understand the nature of the new confined features observed in the STM images of nanopores, we have carefully surveyed the literature. We found that very similar types of confined features have been recently observed after exposure to 300 L of propylene on a clean Ni(111) surface at room temperature . The authors corroborated their experimental observations by DFT simulations.…”

“…The TCNBB molecule exhibits six bright protrusions (white dashed circles in Figure 2d), and each protrusion included in nanopores is attributed to a silicon adatom. This model is also similar to the one observed for the bromine-ended molecule 34 instead of cyano-ended.…”

“…DFT Simulations. DFT calculations were performed using the Siesta package (version 4.1.5), 23,24,34 within the vdW-DF2 functional limit. 25 The Si(111)-B substrate was modeled by a large unit cell of 783 atoms (588 Si, 49 B, and 146 H) terminated with hydrogen atoms to avoid the presence of Si dangling bonds.…”

In Situ Observation of C−C Coupling and Step Poisoning During the Growth of Hydrocarbon Chains on Ni(111)

“…[13,[19][20][21] Small hydrocarbon molecules were directly dosed on model catalyst surfaces, [22,23] forming polymeric chains. [24][25][26] A recent in situ STM study clarified the growth process of polyethylene on a carburized Fe(110) surface, unraveling the ethylene insertion mechanisms proposed by Cossee for Ziegler-Natta catalysts. [3] In this case, the active sites were identified as the boundaries between the iron carbide domains.…”

“…In an attempt to investigate the C−C bond formation step, ultra‐high vacuum (UHV) studies have been reported [13, 19–21] . Small hydrocarbon molecules were directly dosed on model catalyst surfaces, [22, 23] forming polymeric chains [24–26] . A recent in situ STM study clarified the growth process of polyethylene on a carburized Fe(110) surface, unraveling the ethylene insertion mechanisms proposed by Cossee for Ziegler–Natta catalysts [3] .…”