Graphene has attracted a lot of research interest owing to its exotic properties and a wide spectrum of potential applications. Chemical vapor deposition (CVD) from gaseous hydrocarbon sources has shown great promises for large-scale graphene growth. However, high growth temperature, typically 1000 °C, is required for such growth. Here we demonstrate a revised CVD route to grow graphene on Cu foils at low temperature, adopting solid and liquid hydrocarbon feedstocks. For solid PMMA and polystyrene precursors, centimeter-scale monolayer graphene films are synthesized at a growth temperature down to 400 °C. When benzene is used as the hydrocarbon source, monolayer graphene flakes with excellent quality are achieved at a growth temperature as low as 300 °C. The successful low-temperature growth can be qualitatively understood from the first principles calculations. Our work might pave a way to an undemanding route for economical and convenient graphene growth.
Graphene has attracted intense research interest due to its exotic properties and potential applications. Chemical vapor deposition (CVD) on Cu foils has shown great promises for macroscopic growth of high-quality graphene. By delicate design and control of the CVD conditions, here we demonstrate that a nonequilibrium steady state can be achieved in the gas phase along the CVD tube, that is, the active species from methane cracking increase in quantity, which results in a thickness increase continually for graphene grown independently at different positions downstream. In contrast, uniform monolayer graphene is achieved everywhere if Cu foils are distributed simultaneously with equal distance in the tube, which is attributed to the tremendous density shrink of the active species in the gas phase due to the sink effect of the Cu substrates. Our results suggest that the gas-phase reactions and dynamics are critical for the CVD growth of graphene and further demonstrate that the graphene thickness from the CVD growth can be fine-tuned by controlling the gasphase dynamics. A similar strategy is expected to be feasible to control the growth of other nanostructures from gas phases as well.
London dispersion force is ubiquitous in nature, and is increasingly recognized to be an important factor in a variety of surface processes. Here we demonstrate unambiguously the decisive role of London dispersion force in non-equilibrium growth of ordered nanostructures on metal substrates using aromatic source molecules. Our first-principles based multi-scale modeling shows that a drastic reduction in the growth temperature, from ,10006C to ,3006C, can be achieved in graphene growth on Cu(111) when the typical carbon source of methane is replaced by benzene or p-Terphenyl. The London dispersion force enhances their adsorption energies by about (0.5-1.8) eV, thereby preventing their easy desorption, facilitating dehydrogenation, and promoting graphene growth at much lower temperatures. These quantitative predictions are validated in our experimental tests, showing convincing demonstration of monolayer graphene growth using the p-Terphenyl source. The general trends established are also more broadly applicable in molecular synthesis of surface-based nanostructures. , and molecular assembly at surfaces 6,7 . To a large extent, such advances through quantitative definitive studies were enabled by the availability of more accurate descriptions of the weak interactions associated with long-range electron correlation effects within first-principles approaches [8][9][10] . In this study, we exploit the power of predictive modeling using state-of-the-art first-principles calculations within density functional theory (DFT), coupled with kinetic rate equation analysis and definitive experimental tests, to establish unambiguously the decisive role of London dispersion force in molecular self-assembly of aromatic source molecules. We choose graphene growth on Cu substrates as an important class of prototypical model systems, and the microscopic mechanisms revealed are broadly applicable in other nanofabrication processes via molecular assembly.Because of its exotic electronic properties [11][12][13][14][15]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.