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monochromated Cu Kα1 radiation (incident angle=0.5°, λ=
which suggests that electrons migrate from GD@CuI to Pt
species. Meanwhile, Schottky barrier can be formed between Pt
nanoparticles and GD@CuI due to Pt nanoparticles have a larger
work function of À 5.60 eV), which confirms also that charges
transfer from GD@CuI to Pt species. The FI-TR spectra is applied
to identify the chemical bonding nature for as-prepared graph-
diyne as shown in Figure 1 h. The major bands were detected
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.541 Å, step size=0.5°, integration time 20 s/step). Fourier trans-
form infrared spectroscopy (FT-IR) spectra of the as-prepared
samples were recorded on FTIR-650 spectrometer. Raman spectro-
scopic investigation was studied on Renishaw-2000 Raman spec-
trometer. Transmission electron microscopy (TEM) images were
collected on a transmission electron microscope (JEM1200EX, JEOL)
equipped with an energy dispersive X-ray detector (EDX) at an
acceleration voltage of 100 kV. X-ray photoelectron spectroscopy
(XPS) spectra was recorded on an X-ray photoelectron spectroscope
(XPS, ESCALAB 250Xi) using an Al Kα source. UV-visible diffuse
reflectance spectra (UV-vis DRS) of GD, CuI and GD-CuI were
recorded on an UV-2550 spectrophotometer. Photoluminescence
À 1
at 1570 and 1711 cm , which are correspond to the skeletal
[26,27]
vibrations of the aromatic ring in the graphdiyne.
Because
of the perfect molecular symmetry, the slight band is appeared
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À 1
at 2198 cm , which assigned to the typical C�C stretching
[12,15,31]
(PL) emission spectra was obtained by operating a FLUOROMAX-4
vibration.
The results of FI-TR indicate the graphdiyne was
spectrophotometer at room temperature (Horiba Scientific). Photo-
electrochemical measurements were manipulated via using an
electrochemical workstation (Versa stat 4, Advanced Measurement
Technology, Inc. America).
synthesized successfully on surface of CuI by a cross-coupling
reaction of the hexa(ethynyl)benzene monomer.
Raman spectroscopic investigation was also conducted to
demonstrate the type of chemical bond in the complex CuI-GD
(
Figure 1i). For composite catalyst CuI-GD, the peaks at
À 1
À 1
2
.3. Photo-catalytic activities measurement
1392 cm
and 1575 cm
are assigned to the breathing
2
vibration of sp carbon domains (D band) and the first order
scattering of the E2 g mode for in-phase stretching vibration of
sp carbon lattice (G band) in aromatic rings, respectively.
Photo-catalytic hydrogen evolution experiments were conducted in
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a quartz glass reactor ca. 63 cm . In a typical photo-catalytic
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[15,28]
experiment, 10 mg of catalyst was suspended in 30 ml of 15%v/v
triethanolamine solution (pH=9). Then, the system was degassed
In
À 1
addition, the band at 1940 and 2197 cm can be assigned to
by bubbling N gas to remove oxygen. The photo-catalytic process
[29]
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the vibration of conjugated diyne links (À C�CÀ C�CÀ ).
was manipulated in a multi-channel photo-catalytic reaction system
equipped with 5-W light emitting diode lamp as a light source and
magnetic stirring as a device ensuring the catalyst was suspended
and dispersed in the solution. The amount of hydrogen evolution
was detected by a gas chromatography with TCD detector (Tianmei
The X-ray diffraction pattern (Figure 1j) for the original CuI
has nine obvious peaks at 25.6, 29.6, 42.3, 50.2, 52.5, 61.3, 67.6,
69.5 and 77.3
°
, corresponding to (111), (200), (220), (311), (222),
(400), (331), (420) and (422) plane of cubic CuI (JCPDS 76–0207),
respectively. To further verify the GD on the surface of CuI, we
removed the CuI in the GD-CuI composite with ammonia water.
The diffraction peaks of CuI are not observed in XRD pattern of
pure GD, which demonstrate the CuI was removed reasonably
from the GD-CuI composite catalyst, as well as pure GD is
successfully obtained. GD unfolds a evidently weak and broad
XRD peak at approximately 23°, attributing to the characteristic
GC7900, 5 A column, N as carrier).
2
2. Results and discussion
2
.1. Chemical structure analysis
[32,33,34]
We directly synthesized a film of graphdiyne based on CuI as a
new carrier by cross-coupling. In this process, the hexa(ethynyl)
benzene monomer was linked by a coupling action. The XPS
spectrum of the C1s in the GD (Figure 1a) shows four peaks
about at 284.5, 285.2, 286.8 and 288.5 eV, which are assigned to
(002) plane of amorphous carbon materials.
Consequently,
the XRD pattern for composite catalyst GD-CuI exhibits similar
characteristic peaks to original CuI. However, the intensity of
diffraction peaks of CuI decreases obviously after coupling GD,
which means that the one-step construction method is
successful for the preparation of GD-CuI hybrids. In addition, it
can be clearly from the high-resolution XPS survey of GD and
GD-CuI (Figure 1k-l) that CuI in the GD-CuI was successfully
removed after ammonia treatment, consistent with the result of
XRD.
2
[24,25]
the CÀ C (sp ), CÀ C (sp), CÀ O and C=O, respectively.
However, the C1s in the GD-CuI (Figure 1b) exhibits a left-shift
binding energy comparing to one in the GD, which implies that
electrons may migrate from GD to CuI. The XPS spectrum of the
Cu 2p in the CuI (Figure 1c) exhibits two peaks at 932.0 and
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51.8 eV, which were attributed to Cu 2p3/2 and Cu 2p1/2. By
contraries, the binding energies of Cu 2p in the GD-CuI express
a right shift consistent with the shift of binding energies for I 3d
2.2. Morphology and structure
(
Figure 1F), which confirms the charges transfer between GD
and CuI. Figure 1e shows the XPS spectrum of I 3d, the binding
energies at 619.5 and 631.0 eV are assigned to I 3d5/2 and I 3d3/2
A typical low-magnification transmission electron microscopy
(TEM) image of GD is exhibited in Figure 2a, revealing clearly
the lamellar structure of GD. Meanwhile, the TEM images for
composite material GD-CuI are also showed in Figure 2(a-b),
unfolding that the distinct flaky GD appeared on edge of bulk
CuI. Furthermore, the high-resolution electron microscopy
(HRTEM) patterns of GD and GD-CuI further illustrate that the
lattice spacing of CuI is 0.374 nm for the (420) lattice planes and
the existence of amorphous GD growing on the edge of bulk
,
respectively. Meanwhile, the XPS spectrum of Pt species loaded
on the surface of GD@CuI was also performed as shown in
Figure 1 g, the binding energies at 72.8 and 76.1 eV are
assigned to Pt 4f7/2 and Pt 4f5/2, respectively. Obviously, the both
binding energies corresponding to Pt 4f7/2 and Pt 4f5/2 species
on the surface of GD@CuI shift right compared to the binding
energies of single Pt 4f7/2 (71.0 eV) and Pt 4f5/2 (74.4) species,
ChemCatChem 2020, 12, 1–12
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