Microsoft Word - Carbon_Supporting Information_GNSPs_Hsu_new

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Supporting Information:

Figure S1.

(a)

A schematic of the experimental setup used for 1,2-DCB and 1,2- DBB.

We control the partial pressures of 1,2-DCB and 1,2- DBB via a leak valve between the

molecule container and growth chamber.

(b)

A schematic of the experimental setup

used for 1,8-DBN. The precursor was heated from 60 °C to 100 °C to introduce different

precursor partial pressures.

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The vapor pressure of 1,2-dichlorobenzene (1,2-DCB) at room temperature is 1.36

mmHg, and 1,2-dibromobenzene (1,2-DBB) is predicted to have a vapor pressure of

0.101 mmHg

. Since the vapor pressure of 1,2-DBB is one order of magnitude smaller

than that of 1,2-DCB, the size of the GNS

Ps grown by 1,2-DBB tends to decrease due

to less amounts of precursor available to form GNSPs.

1,8-dibromonapthalene (1,8-DBN) is in a solid form in room temperature. It was placed

in a quartz boat and was heated up in a furnace. The temperature of the furnace ranged

from 60 °C to 100 °C, which corresponded to a range of different precursor partial

pressures.

Figure S2.

(a) SEM image (top) and Raman spectrum (bottom) of GNSPs on Cu foil

grown by 1,2-DBB for 10 minutes. (b) SEM image (top) and Raman spectrum (bottom)

of GNSPs on Cu foil grown by 1,2-DBN for 10 minutes. 1,2-DBN was heated up to

80°C to produce enough vapor pressure.

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Figure S3. (a)

SEM image (top) and Raman spectrum (bottom) of GNSPs on Ni foam

grown by 1,2-DCB for 10 minutes.

(b)

SEM image (top) and Raman spectrum (bottom)

of GNSPs on Ni foil grown by 1,2-DCB for 10 minutes.

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Figure S4. (a)

SEM top view and

(b)

tilted view of GNSPs on Cu foil fabricated by

PECVD with toluene as the seeding molecules for 20 minutes at 40 W plasma power.

(c)

Raman spectrum of the same GNSPs samples as shown (a) and (b).

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Figure S5.

Optical emission spectroscopy (OES) of PECVD-grown GNSPs under

different 1,2-DCB/CH

partial pressure ratios, showing decreasing intensities of all

hydrogen related peaks with increasing1,2-DCB

partial pressure. On the other hand, the

intensity of C

radicals, critically important for graphene growth, is enhanced upon the

introduction of 1,2-DCB precursor molecules, although no further increase appears

with increasing 1,2-DCB partial pressure.

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Figure S6.

Evidences of strong optical absorption by GNSPs: The main panel shows

the optical transmission spectrum of GNSPs for wavelengths from 400 nm to 800 nm,

revealing transmission < 0.1% for the entir

e range of wavelengths. The inset shows

micrographs of a copper substrate

(a)

before and

(b)

after the growth of GNSPs. The

growth parameters for the micrograph in (b) are given in the last row of Table 1. Here

we note that the transmission spectrum was obtained by using a Cary 5000 absorption

spectrometer with an integrating sphere, and the GNSPs were transferred from the Cu

substrate onto a quartz substrate for the op

tical measurement. The incident light was

sent through the entire GNSP sheet and the underlying quartz substrate and then was

collected by a detector. The baseline signal of

the spectrum was obtained by subtracting

the transmission signals from a blank quartz substrate as the reference.

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Figure S7. (a)

(Left) Setup of the dielectrophoresis method

2,3

to align GNSPs on the

Au electrodes. The procedure for aligning the GNSPs is as follows: We immersed the

copper foils covered by GNSPs in dichlorobenzene solvent for 20 hours to lift GNSPs

off the copper foils, and then sonicated the suspension for 3 minutes to break down big

chunks of GNSPs. Then we used a micropipette to drop the suspension onto a set of Au

electrodes where an AC field of a frequency 500 kHz was applied while the voltage

steadily increased up to 60 volts and kept on until the dichlorobenzene evaporated

completely at room temperature. (Right) A SEM image of a GNSP on four Au

electrodes.

(b)

AFM cross-section of the image along the blue line in the SEM image

of (a). From our TEM studies, we found that the interlayer distances of the multilayer,

turbostratic GNSPs ranged from 0.355 nm to 0.394 nm, larger than the interlayer

spacing (0.335 nm) of pristine graphite. Thus, from the resistivity and thickness

measurements of aligned GNSPs using the di

electrophoresis method, we obtained the

sheet resistance of a single layer GNSPs to be ranging from ~ 7.0 k



to ~ 7.8 k



at room temperature, which were larger than the typical pristine graphene sheet

resistance (~ 1 k



), but were significantly smaller than typical values (~ 50 k



~ 30 k



) reported for lithographically patterned single-layer GNSPs of comparable

widths (100 nm ~ 1



m).

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Figure S8:

3D energy minimization model

Fig. 4-VI

, where yellow represents carbon,

green represents chlorine, and gray represen

ts hydrogen. This model shows that a 1,2-

DCB-saturated zigzag graphene edge is highly strained and results in branching.

TEM Sample Preparation

In order to perform transmission electron microscopy (TEM) measurements, the

GNSPs were dispersed in an IPA solution po

st-growth by sonicating the sample to

remove the GNSPs from the Cu foil. A pipette was used to deposit a 0.1 ml droplet on

a Cu TEM sample grid and the IPA was then allowed to evaporate. The Cu TEM grids

was then imaged in an SEM to verify sample

transfer before measurements with a TEM.

The TEM measurements were performed on a FEI Tecnai TF30 STEM (TF30) with an

operating voltage of 300KV. Samples were imaged from 500 microns down to 5

nanometers with Selected Area Diffract

ion (SAD) and Energy-dispersive X-ray

spectroscopy (EDS) were performed on selected regions of the samples.

REFERENCES

O-Dibromobenzene (n. d.) EPISuite [software] available from

http://www.chemspider.com/Chemical-Structure.13875212.html

R. Krupke, F. Hennrich, H. V. Löhneysen, M. M. Kappes, Separation of metallic

from semiconducting single-walled carbon nanotubes.

Science

2003

301

, 344-347.

A. Vijayaraghavan, C. Sciascia, S. Dehm, A. Lombardo, A. Bonetti, A. C. Ferrari,

et al. Dielectrophoretic assembly of high-

density arrays of individual graphene

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devices for rapid screening.

ACS Nano

2009

, 1729–1734.

Z. J. Qi, J. A. Rodríguez-Manzo, A. R. Botello-Méndez, S. J. Hong, E. A. Stach, Y.

W. Park, et al. Correlating atomic structure and transport in suspended graphene

nanoribbons.

Nano Lett.

2014

, 4238

−

4244.