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Supporting Information
Significant field emission enhancement in ultrathin nano-thorn covered NiO
nano-petals
Suryakant Mishra1, Priyanka Yogi1, Shailendra K. Saxena1, J. Jayabalan2,3, Prakash Behera4, P.R.
Sagdeo1 , Rajesh Kumar1*
1Material Research Laboratory, Discipline of Physics & MEMS, Indian Institute of Technology Indore,
Simrol-453552 India.
2 Nano Materials Laboratory, Materials Science Section, Raja Ramanna Centre for Advanced
Technology, Indore - 452013, India.
3 Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai - 400094,
India.
4 UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001
Figure S1: (a, b) AFM images of NiO-NPs grown on FTO substrate in 2D and 3D view. (c) high
resolution image with(d) line profiling.
(a) (b)
(c)
500nm
100nm
(d)
798.99 nm
0.00 nm
489 nm
0 nm
798.99 nm
0.00 nm
799 nm
0 nm
798.99 nm
0.00 nm
400 nm
0 nm
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C.This journal is © The Royal Society of Chemistry 2017
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Figure S2: Surface morphologies of NiO nanopetals grown by hydrothermal process with
deposition time of (a) 2 hrs. (b) 3 hrs. (c) 4 hrs. and (d) 5 hrs.
200nm
200nm 200nm
~25nm
200nm
(a) (b)
(c) (d)
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Figure S3: (a) Cross-sectional SEM image of NiO-NPs (b) schematic view of single nanopetal to show
sharp needles like edges on the top (c) broad area view of the same.
10mm
1mm
10mm
(a)
(b)
(c)
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Figure S4: (a, b) SEM image of the NiO-NPs film scratch-off from the FTO substrate to show the
alignment and uniformity of the film. Scale bar in the images correspond to 2 mm
Figure S5: (a) SEM image of NiO-NPs with their corresponding (b) EDX spectrum and (c) XPS survey
scan and (d) Ni-2P elemental scan of the same recorded at 10 degree. Experimental details about XPS
measurements have been given below.
(a) (b)
1000 800 600 400 200 0
Inte
nsi
ty (
a.u
.)
Binding energy (eV)
Ni
3p
Si
2pC 1
s
Sn
3d
O 1
s
Ni
LM
M
Ni
LM
M
Ni
2p
OK
LL
Ni
LM
M
890 880 870 860 850
Inte
nsi
ty (
a.u
.)
Binding energy (eV)
NiO
NiO
Satellite
Satellite
Ni 2p
(a)
(c) (d)
(b)
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XPS measurements
The x-ray photoelectron spectroscopy (XPS) measurements as shown in Figures S5 (c) and (d)
have been performed using Specs (Germany) XPS system. The said XPS system is equipped
with 150 mm hemi-spherical analyzer and with Al Kα (1486.6 eV) X-ray source. Prior to XPS
measurements the surface of the sample was properly cleaned using in built argon ion sputtering
gun. All measurements were performed at room temperature and at working pressure of 5 x 10-9
Torr, the pass energy was kept at 20 eV and the dwell period was 0.1 Seconds. The energy
resolution of the XPS system is 0.85 eV. Ten number of scans were recorded and averaged to
obtain the final spectra. As the prepared flakes NiO samples are approximately perpendicular to
the plane of the substrate hence the XPS data were collected at two different angles of 10 and 70
degrees to optimize the signal. The spectrum in Figure S5(d) are similar to the one reported by
chen et al1. which is suggestive of presence of NiO in our sample. The peak near 855 eV
indicates that nickel in the form of Ni(OH)2 might also be present2
Figure S6: Morphological analysis of nanopetals, for fetching nanothorns on the petal like structures,
using line scanning by ImageJ software.
2600 nm
22
00
nm
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Figure S7: Electric field cycles (Figure 5a inset, main text).
01
00
02
00
03
00
04
00
05
00
06
00
0
0
10
0
20
0
30
0
J(mA/cm2)
Tim
e(s
)
01
00
02
00
03
00
04
00
05
00
06
00
0
0123456E(V/mm)
Tim
e(s
)
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Figure S8: Emission current cycles (Figure 5b inset, main text).
01
00
02
00
03
00
04
00
05
00
06
00
0
0
10
0
20
0
30
0J(mA/cm
2)
Tim
e(s
)
01
00
02
00
03
00
04
00
05
00
06
00
0
0123456
E(V/mm)
Tim
e(s
)
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References
1 Y. Chen, Y. Wang, P. Sun, P. Yang, L. Du and W. Mai, J. Mater. Chem. A, 2015, 3, 20614–20618. 2 M. C. Biesinger, B. P. Payne, L. W. M. Lau, A. Gerson and R. S. C. Smart, Surf. Interface Anal., 2009, 41,
324–332.
