Year-end Sale % OFF 
Abstract
Diverse technologies from catalyst coking to graphene synthesis entail hydrocarbon dehydrogenation and condensation reactions on metals and assembly into carbon overlayers. Imperative to gaining control over these processes, through thermal steering of the formation of polyaryl intermediates and the controlled prevention of coking, is the exploration and elucidation of the detailed reaction scheme that starts with adsorbed hydrocarbons and culminates with the formation of extended graphene. Here we use scanning tunneling microscopy, high-resolution electron energy loss and thermal desorption spectroscopies, in combination with theoretical simulations to uncover the hierarchy of pathways and intermediates underlying the catalyzed evolution of ethene adsorbed on Rh(111) to form graphene. These investigations allow formulation of a reaction scheme whereby, upon heating, adsorbed ethene evolves via coupling reactions to form segmented one-dimensional polyaromatic hydrocarbons (1D-PAH). Further heating leads t...
Highlights
The formation of solid carbonaceous, carbidic, or graphitic material known as coke,[1,2] derived through anaerobic processing of organic material on metal surfaces at elevated temperatures, has been known since antiquity and patented since the late 16th century for iron ore smelting and making of steel.[3]
More recent studies have utilized modern surface science techniques (low-energy electron microscopy, low-energy electron microscopy,[18,19] Xray photoelectron spectroscopy,[20] and scanning tunneling microscopy (STM)21), extended observations into the graphene formation domain, and resulted in valuable insights into the growth kinetics, suggesting the role of carbon clusters whose attachment, rather than that of monomers, leads to ripening and graphene growth; the carbon-cluster hypothesis has been incorporated in a phenomenological kinetic Monte Carlo simulation of the growth process.[24]
The research reported focuses on gaining insights into the atomic-scale mechanisms of bottom-up chemical pathways that govern the molecular assembly processes resulting in formation of extended graphene structures
Summary
The formation of solid carbonaceous, carbidic, or graphitic material known as coke,[1,2] derived through anaerobic processing of organic material on metal surfaces at elevated temperatures, has been known since antiquity and patented since the late 16th century for iron ore smelting and making of steel.[3]. Investigations yielded a wealth of information about the surface chemistry (e.g., catalyzed C−H bond activation and coupling reactions) of small alkane and alkene molecules on metal surfaces (see refs 16 and 17, and references therein). More recent studies (in particular on ethene deposited on transition metal surfaces) have utilized modern surface science techniques (low-energy electron microscopy, low-energy electron microscopy,[18,19] Xray photoelectron spectroscopy,[20] and scanning tunneling microscopy (STM)21), extended observations into the graphene formation domain, and resulted in valuable insights into the growth kinetics, suggesting the role of carbon clusters (comprised of 5,18,19 21,22,23 or 2421 atoms) whose attachment, rather than that of monomers, leads to ripening and graphene growth; the carbon-cluster hypothesis has been incorporated in a phenomenological kinetic Monte Carlo simulation of the growth process.[24]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
