Interdependency of subsurface carbon distribution and graphene-catalyst interaction.

Robert S Weatherup,Pierre Seneor,Raoul Blume,Cyrile Deranlot,Bruno Dlubak,Mounib Bahri,Sabina Caneva,François Ducastelle,Robert Schloegl,Hakim Amara,Bernhard C Bayer,Piran R Kidambi,Stephan Hofmann,Andrea Cabrero-Vilatela,Marie-Blandine Martin,Mamadou Diarra,Christophe Bichara

doi:10.1021/ja505454v

Abstract

The dynamics of the graphene–catalyst interaction during chemical vapor deposition are investigated using in situ, time- and depth-resolved X-ray photoelectron spectroscopy, and complementary grand canonical Monte Carlo simulations coupled to a tight-binding model. We thereby reveal the interdependency of the distribution of carbon close to the catalyst surface and the strength of the graphene–catalyst interaction. The strong interaction of epitaxial graphene with Ni(111) causes a depletion of dissolved carbon close to the catalyst surface, which prevents additional layer formation leading to a self-limiting graphene growth behavior for low exposure pressures (10–6–10–3 mbar). A further hydrocarbon pressure increase (to ∼10–1 mbar) leads to weakening of the graphene–Ni(111) interaction accompanied by additional graphene layer formation, mediated by an increased concentration of near-surface dissolved carbon. We show that growth of more weakly adhered, rotated graphene on Ni(111) is linked to an initially higher level of near-surface carbon compared to the case of epitaxial graphene growth. The key implications of these results for graphene growth control and their relevance to carbon nanotube growth are highlighted in the context of existing literature.

Highlights

Catalytic techniques for producing graphene and carbon nanotubes (CNTs), those based on chemical vapor deposition (CVD), are widely seen as most promising for achieving the requisite level of control over material structure and quality that is demanded by applications.[1,2] Key to growth control is a detailed understanding of the role of the catalyst, which remains incomplete due the wide parameter space, and for CNT CVD, the complexity of nanoparticulate catalysts.[3]
The dynamics of the graphene−catalyst interaction during chemical vapor deposition are investigated using in situ, time- and depthresolved X-ray photoelectron spectroscopy, and complementary grand canonical Monte Carlo simulations coupled to a tight-binding model
There has been a great deal of recent progress in studying catalyst interactions for growing graphene on planar surfaces.[4−8] Such systems have model character in terms of catalytic CVD of all other carbon nanostructures inasmuch as flat, well-defined catalyst surfaces have been used for decades in surface science as model systems for nanoparticulate catalysts typically used in industrial heterogeneous catalysis.[3,9]

Summary

Introduction

Catalytic techniques for producing graphene and carbon nanotubes (CNTs), those based on chemical vapor deposition (CVD), are widely seen as most promising for achieving the requisite level of control over material structure and quality that is demanded by applications.[1,2] Key to growth control is a detailed understanding of the role of the catalyst, which remains incomplete due the wide parameter space, and for CNT CVD, the complexity of nanoparticulate catalysts.[3]. Recent literature on graphene CVD has focused on the control of nucleation density[10−13] and epitaxial[6,14,15] or pseudoepitaxial[16,17] relationships that can exist between specific catalyst surfaces and the growing graphene. It is important to note that crucial to CVD growth control is the graphene− catalyst interaction at elevated temperatures during precursor exposure. Under these reaction conditions the physical and chemical state of the catalyst surface is highly dynamic, driven by process conditions and catalyst exposure history,[6,7,18,19] and the graphene−catalyst interaction can be dynamic. Given the 1 × 1 epitaxial match between graphene and Ni(111)

Methods

Results

Discussion

Conclusion