Photocatalytic Mechanism Control and Study of Carrier Dynamics in CdS@C3N5 Core–Shell Nanowires

S1
SUPPORTING INFORMATION
Photocatalytic mechanism control and study of carrier
dynamics in CdS@C3N5 core-shell nanowires
Kazi M. Alam,1, 5*
Charles E. Jensen,2
Pawan Kumar,1
Riley W. Hooper,3
Guy M. Bernard,3
Aakash
Patidar,4
Ajay P. Manuel,1
Naaman Amer,2
Anders Palmgren,2
David N. Purschke,2
Narendra
Chaulagain,1
John Garcia,1
Phillip S. Kirwin,1
Lian C. T. Shoute,1
Kai Cui,5
Sergey Gusarov,5
Alexander
E. Kobryn,5
Vladimir K. Michaelis,3
Frank A. Hegmann2
and Karthik Shankar1
∗
1
Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
2
Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
3
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
4
Department of Chemistry, Indian Institute of Technology Kharagpur, West Bengal 721302, India
5
Nanotechnology Research Centre, National Research Council Canada, Edmonton, AB T6G 2M9, Canada
Contents
S1. Materials and Methods........................................................................................................................ 2
S1.1 Structural and physicochemical characterization............................................................................. 2
Photoluminescence spectroscopy (PL). A PTI fluorescence spectrophotometer (QuantaMaster 40
intensity based spectrofluorometer) equipped with a high efficiency continuous xenon arc lamp, was
used to collect the steady state photoluminescence (PL) spectra of the samples. The excitation
wavelength was 400 nm.............................................................................................................................. 4
S1.2 Modeling and computation ............................................................................................................... 7
S2. Supplementary Figures ........................................................................................................................ 9
S2.1 HRTEM images, EELS line scan and elemental mapping of CdS-MHP and CdS-MHPINS showing
wrapping of C3N5 around the CdS nanowires and the distribution of C, S and Cd................................. 9
................................................................................................................................................................... 10
Figure S2. Electron energy-loss spectra (EELS) 2-D line scan along the diameter of CdS-MHP [(a) and
(b)] and CdS-MHPINS [(c) and (d)] showing the distribution of C, S and Cd. The green lines in (a) and
(c) correspond to the plots in (b) and (d) respectively.............................................................................. 10
S2.2 Fits of the optical spectra of CdS, CdS-MHP and CdS-MHPINS to the sigmoidal Boltzmann
function..................................................................................................................................................... 12
S2.3 FDTD electromagnetic simulation ................................................................................................... 13
S2.4 XPS valence band spectra of pristine bulk CdS, bulk C3N5 and C3N5 nanosheets ....................... 17
S2.5 Band gap extraction from UV-vis spectra using Kubelka-Munk formula....................................... 17
S2.6 UPS work function of pristine bulk CdS and C3N5 nanosheets....................................................... 18
S2.7 1H magic angle spinning NMR spectra............................................................................................ 19
S2.8 TRTS schematics ............................................................................................................................... 20
∗ Tel: 780-492-1354; email: kshankar@ualberta.ca

S2
................................................................................................................................................................... 20
S2.9 Steady-state photoconductivity plots of CdS, CdS-MHP and CdS-MHPINS ................................... 21
S2.10 Rhodamine B photodegradation spectra in the presence of active species trapping agents..... 21
S2.11 Infrared spectra.............................................................................................................................. 25
S2.12 Steady state PL spectra in aqueous RhB solution......................................................................... 26
S2.13 Reusability test of photocatalysts for Rhodamine B photodegradation ..................................... 27
S2.14 4-nitrophenol photodegradation data.......................................................................................... 28
S2.15 Nitrogen adsorption-desorption isotherm for pristine bulk CdS, CdS-MHP and CdS-MHPINS... 31
................................................................................................................................................................... 31
Figure S29. N2 adsorption-desorption isotherms of (a) pristine CdS, (b) CdS-MHP and (c) CdS-
MHPINS samples...................................................................................................................................... 31
S2.16 DFT Optimized structures for CdS-C3N5 heterojunctions ............................................................ 32
S2.17 DFT calculated electron density difference isosurfaces for CdS-C3N5 heterojunctions ............. 33
S2.18 DFT calculated HOMO-LUMO plots for bare CdS and single layer bare C3N5............................. 34
S2.19 DFT calculated orbital-resolved PDOS spectra for bare CdS ........................................................ 35
S3. Supplementary Tables........................................................................................................................ 36
S3.1 Zeta potential in aqueous medium ................................................................................................. 36
S3.2 Crystallite size and microstrain........................................................................................................ 36
S3.3 Terahertz photoconductivity and decay data................................................................................. 37
S3.4 Fit parameters for terahertz photoconductivity data..................................................................... 37
S3.5 BET surface area, pore volume and pore size from N2 adsorption-desorption isotherm ............ 38
S4. References .......................................................................................................................................... 38
S1. Materials and Methods
S1.
S1.
S1.
S1.1
1
1
1 Structural and physicochemical characterization
Structural and physicochemical characterization
Field emission scanning electron microscopy (FESEM) imaging. A field emission scanning electron
microscope (Zeiss Sigma FESEM) operating at an accelerating voltage of 5 kV, was used to obtain
morphological features of CdS, CdS-MHP and CdS-MHPINS.
Transmission electron microscopy (TEM) imaging and electron energy-loss spectroscopy (EELS). Hitachi
H9500 transmission electron microscope (TEM), equipped with a Lab6 emission gun was used to study
the fine structural features of pristine and composite materials. The accelerating voltage was 300 kV. The
inner shell ionization edge (core loss) spectra were obtained with electron energy-loss spectroscopy
(EELS). The EELS spectra, line scan and elemental map were recorded under the TEM imaging mode,
recorded on a Gatan GIF Tridium spectrometer. The obtained high-resolution TEM (HR-TEM) images
and EELS project files in .dm3 format were processed with the Digital Micrograph, Gatan Inc. software.

S3
Zeta potential. Zeta potential in aqueous suspensions for CdS, CdS-MHP, CdS-MHPINS and C3N5 NS
were measured using Malvern zetasizer nano-ZS. The suspensions were diluted prior to the measurements.
Malvern nanosizer software was used for the data analysis.
X-ray diffractometry (XRD). A Bruker D8 advance diffractometer with a radiation source of Cu X-ray
tube (Cu-Kα, IμSμ, λ = 0.15418 nm) operating at 50W was used to collect the X-ray powder diffraction
(XRD) spectra. This tool is equipped with a 2D detector (VANTEC-500).
Raman spectroscopy. A Raman spectrometer, Nd:YAG laser Raman Microscope (Nicolet Omega XR)
was used to extract the vibrational properties. The excitation wavelength of the Raman laser was 532 nm.
Low incident power (2 mW) was employed with a fluorescence correction factor of 6. The spectra were
accumulated for 120 seconds using a 50 μm confocal pinhole aperture slit and a 2 cm−1
/CCD pixel element
spectral dispersion grating.
Diffuse reflectance spectroscopy (DRS). A Perkin Elmer Lambda-1050 UV–Vis-NIR spectrophotometer
operating in the diffuse reflectance mode was used to acquire the absorption spectra of CdS, CdS-MHP
and CdS-MHPINS for the solid film samples deposited on a clean glass substrate. This
spectrophotometer is equipped with an integrating sphere accessory. Semiconductors typically exhibit
a spectral region of high optical absorption (αmax) for energies larger than the bandgap and a spectral
region of low absorption (αmin) for energies lower than the bandgap, with a transition region in between.
Hence, S-shaped sigmoidal curves are well-placed to capture this behavior and fitting the optical spectra
to the Boltzmann function can provide more consistency and insight regarding the value of the bandgap
and the energy range over which the electronic transition occurs.1 The absorption spectra were fitted to
the following sigmoidal Boltzmann function to extract the bandgap (E0) and δE parameter (related to the
slope of the band-edge electronic transition)1

S4
= +
1 +
Band gap estimation from DRS spectra was also performed using Tauc plots derived from the Kubelka-
Munk formula by extrapolating the linear region of the graph between (F(R).hν)n
vs hν on abscissa; where
F(R) = K/S, where K and S are absorption and backscattering coefficients. K = (1-R)2
and S = 2R; where
R stands for reflectance. h is the Planck’s constant and ν is the light frequency. In case of indirect
semiconductor (C3N5 bulk and C3N5 NS) the value of the superscript ‘n’ was taken to be 1/2 whereas, for
direct bandgap semiconductor, such as CdS and its heterojunctions, this value was taken as 2. According
to HRTEM and fabrication protocols, the heterojunctions are mostly composed of CdS with a very small
amount of C3N5.
Photoluminescence spectroscopy (PL). A PTI fluorescence spectrophotometer (QuantaMaster 40 intensity
based spectrofluorometer) equipped with a high efficiency continuous xenon arc lamp, was used to collect
the steady state photoluminescence (PL) spectra of the samples. The excitation wavelength was 400 nm.
X-ray photoelectron spectroscopy (XPS). The surface chemical composition and binding energy of various
elements present in the materials were determined using X-ray photoelectron spectroscopy (XPS) using
Axis-Ultra, Kratos Analytical instrument with monochromatic Al-Kα source (15 kV, 50 W; photon energy
1486.7 eV) under ultrahigh vacuum (∼10−8
Torr). The binding energy of all the elements were referenced
with respect to the C1s binding energy ≈ 284.8 eV of adventitious hydrocarbon. Ultraviolet photoemission
spectroscopy (UPS) was used for the determination of Fermi level and work function of the materials. For
the UPS measurement a 21.21 eV He lamp source was used as an excitation source. The value of work
function was calculated using the expression WF (ϕ) = 21.21−Ecut-off ; where Ecut-off is the cut-off energy
of secondary electrons. This value of cut-off energy of secondary electrons Ecut-off was obtained by
extrapolating the leading edge (longest straight line) of the graph and finding the point of intersection on

S5
the horizontal line (zero count). The raw electronic data for XPS and UPS were in .vms format which
were deconvoluted into peak components using CasaXPS software.
Solid state nuclear magnetic resonance (NMR) spectroscopy. To elucidate the chemical structure of
materials solid-state 113
Cd and 13
C nuclear magnetic resonance (NMR) spectra were acquired. Solid-state
113
Cd NMR spectra were acquired on a Bruker Avance III HD 400 NMR spectrometer (B0 = 9.4 T)
equipped with a 4 mm double-resonance (H-X) Bruker magic-angle spinning (MAS) probe. Spectra were
acquired at natural abundance using a typical Bloch-decay experiment with a 4.0 µs π/2 pulse and a recycle
delay of 120 seconds, under MAS conditions (νr = 12 kHz). To detect surface Cd nuclei, 113
Cd NMR
spectra were also acquired with the ramped CP technique. These spectra were acquired at a spinning
frequency of 14 kHz with a 4 µs 1
H π/2 pulse, a 5 ms contact time and a recycle delay of 3.0 s; from 56000
to over 137000 transients were co-added to detect these dilute nuclei. 113
Cd MAS NMR spectra were
referenced to 0.1 M Cd(ClO4)2 (δ(113
Cd) = 0.00 ppm) by setting the 113
Cd peak of solid Cd(NO3)2·4H2O
to −100 ppm. 13
C NMR spectra were acquired on Bruker Avance 500 (B0 = 11.75 T) or the Avance III
400 NMR spectrometers, both with a 4 mm MAS NMR probes operating in double resonance mode.
Spectra of natural abundance samples were acquired using the CP technique, with contact times of 3 ms,
a 4.0 μs 1
H π/2 pulse, a recycle delay of 3.0 s, and with broadband proton decoupling via two-pulse phase
modulation (TPPM),2
under MAS conditions (νr = 10 kHz). 13
C NMR spectra were referenced to TMS
(δ(13
C) = 0.00 ppm) by setting the high frequency 13
C peak of solid adamantane to 38.56 ppm.3
All the
powdered samples were packed into 4 mm zirconia rotors prior to the experiments.
Time-resolved terahertz spectroscopy (TRTS). Charge carrier dynamics in pristine CdS nanowires and the
hybrids was investigated by optical pump-terahertz (THz) probe spectroscopy. The nanowire samples
were dissolved in methanol followed by magnetic stirring and ultrasonication. These nanowire-containing
solutions were drop-cast on sapphire glass and heated on a hot plate at 60 °C for 30 minutes to remove

S6
methanol. Samples were mounted in a nitrogen-purged chamber and illuminated with a pump laser of
100 fs pulses at a wavelength of 410 nm and a fluence of 200 μJ/cm2
. An optical rectification of 100 fs,
800 nm pulses in 1 mm thick ZnTe (110) crystal was employed to generate THz probe pulses. An off-axis
parabolic mirror was used to focus this THz pulse onto the samples through a spot size of 1.5 mm diameter.
The transmitted THz pulses were detected by a sensor comprising another 1 mm thick ZnTe (110) crystal,
using free-space electrooptic sampling. All the measurements were conducted at room temperature.
Steady-state photoconductivity. Steady-state current-voltage (I-V) characteristics were derived from two
terminal measurements using a Keithley 4200 semiconductor parameter analyzer. Solutions of CdS, CdS-
MHP and CdS-MHPINS in methanol (30 mg/ml) were drop-coated on FTO glass substrate, followed by
drying on a hot plate. 80 nm thick Au contacts were deposited on these FTO-coated samples by electron
beam evaporation using a shadow mask (16 contacts on each sample). The voltage was swept between
+3V and −3V. Transport measurements were conducted in dark and under AM1.5G one sun illumination.
Fourier transform infrared spectroscopy (FTIR). Infrared spectra were obtained using an Agilent
FTS7000 FTIR Imaging System (diamond ATR/attenuated total reflection) and recorded in transmittance
mode. Dry powder samples were transferred onto the diamond crystal prior to the data collection.
BET surface area, pore volume and pore size distribution. The surface areas of the samples (bare CdS,
CdS-MHP and CdS-MHPINS) were calculated by applying the BET (Brunauer–Emmett–Teller) method
to the obtained N2 adsorption-desorption isotherms, recorded at –190 °C by using the Autosorb
Quantachrome 1MP tool. Prior to the analysis experiment, the samples were outgassed under vacuum at
120 °C for 2 hours to remove all moisture and adsorbed gases on the surface. The BET equation was
applied to the nitrogen adsorption isotherm within the relative pressures 0.05 < P/P0 < 0.30. Barret-Joyner-
Halenda (BJH) method applied to the desorption points, was used to determine the pore volume and pore
size distribution.

S7
S1.
S1.
S1.
S1.2
2
2
2 Modeling and computation
Modeling and computation
Finite-difference time-domain (FDTD) electromagnetic simulations. Lumerical FDTD simulation
software was employed for the extraction of the optical properties of bare CdS-nanowires. Four different
geometries were simulated, whose dimensions were chosen according to FESEM images (Figure 1) that
revealed a wide range in nanowire length and diameter. We considered CdS nanowires with two extremal
values of length (200 nm and 1000 nm) and diameter (50 nm and 100 nm). All the simulations were
performed in vacuum. Scattering and absorption cross sections, and electric field intensity profiles were
captured using near, and far-field profile and frequency monitors. A light source (wavelength range of
300-800 nm) was incident on the nanowires in the transverse direction marked by a pink arrow (y-axis in
Figure S3), i.e. perpendicular to the nanowire axis. The excitation source is a TFSF (total-field scattered-
field) source and the electric field polarization is along the z-axis (blue arrow). Lumerical’s in-built
refractive index monitor was used to confirm the appropriateness of the modeled structures in FDTD
simulation. PML (perfectly matched layer) absorbing boundary conditions were utilized, allowing for the
absorption of light waves (both propagating and evanescent) with minimal reflections. The electric field
intensity profiles were obtained at the wavelength of 470 nm, where the absorption is highest (Figure 2)
and viewed along different planes including the xy, xz and yz planes. The nanowire is oriented vertically
on an FTO (fluorine tin oxide) substrate. The horizontal rectangle visible in the plots (Figure 3, S4, S5
and S6) is the substrate. The plotted quantity of the electric field profiles is the electric field intensity or
E2
. The scattering is higher compared to absorption, and significantly enhanced, particularly for the
nanowires with larger diameters. Among the geometries simulated, FDTD simulations of bare CdS NWs
with a diameter of 100 nm and a length of 200 nm generated the best match to the experimentally observed
optical response. The bare CdS nanowire of 200 nm length and 100 nm diameter has been wrapped with
2 nm thick C3N5 (Figure 3) to study the modified optical property and electric field intensity profile of the

S8
stand-alone CdS nanowire. Optical constants for CdS nanowires were obtained from the reported work in
the literature.4
Refractive index data for C3N5 were taken from earlier report on nitrogen-doped carbon
quantum dots5
and our previously reported work on carbon-nitride.6
Quantum chemical simulation. Density functional theory (DFT) was employed for geometry optimization
and electronic property calculations. The OpenMx 3.8 (Open source package for Material eXplorer)
package was used with norm-conserving pseudopotentials and pseudo-atomic localized basis functions.7,
8
The Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional with the general gradient
approximation (GGA)9
has been used as implemented in the package. The dispersion-corrected method
(DFT-D2)10
and spin polarization were employed for all the calculations. Two relevant pristine CdS planes
(100) and (110) having few layers, pristine single layer C3N5
11
and their heterojunctions were constructed
in Materials Studio. CdS planes (100) and (110) in the hexagonal wurtzite phase were chosen for the
construction of the heterojunctions with C3N5, as these two planes were found in the interfacial region
according to obtained HRTEM images discussed in the results and discussion section. Geometry
optimization was performed first, followed by electronic property calculations. Periodic boundary
conditions were employed in this computational scheme. The electron density difference isosurfaces,
highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were
extracted using the VMD (visual molecular dynamics) visualization software. The value of the isosurfaces
was taken to be 0.015 eV Å-3
. The Gaussian broadening method was used for extraction of the density of
states (DOS) plots with a broadening parameter of 0.08 eV.

S9
S2. Supplementary Figures
S2.1
S2.1
S2.1
S2.1 HRTEM images
HRTEM images
HRTEM images
HRTEM images, EELS line scan and elemental mapping
, EELS line scan and elemental mapping
, EELS line scan and elemental mapping
, EELS line scan and elemental mapping of CdS
of CdS
of CdS
of CdS-
-
-
-MHP and CdS
MHP and CdS
MHP and CdS
MHP and CdS-
-
-
-MHPINS
MHPINS
MHPINS
MHPINS
showing wrapping of C3N5 around the CdS nanowire
showing wrapping of C3N5 around the CdS nanowires
s
s
s and the distribution of C, S and Cd
and the distribution of C, S and Cd
Figure S1. HRTEM images showing (a) CdS nanorod wrapped by C3N5 nanosheets in CdS-MHP and (b)
CdS nanorod wrapped by C3N5 nanosheets in CdS-MHPINS samples.

S10
Figure S2. Electron energy-loss spectra (EELS) 2-D line scan along the diameter of CdS-MHP [(a) and
(b)] and CdS-MHPINS [(c) and (d)] showing the distribution of C, S and Cd. The green lines in (a) and
(c) correspond to the plots in (b) and (d) respectively.

S11
Figure S3. Electron energy-loss spectra (EELS) 2-D elemental mapping along the diameter of CdS-
MHP [(a) and (b)] and CdS-MHPINS [(c) and (d)] showing the distribution of C, S and Cd. The green
boxes in (a) and (c) correspond to the map areas in (b) and (d) respectively.

S12
S2.
S2.
S2.
S2.2
2
2
2 Fits of the optical spectra of CdS, CdS
Fits of the optical spectra of CdS, CdS
Fits of the optical spectra of CdS, CdS
Fits of the optical spectra of CdS, CdS-
-
-
-MHP and CdS
MHP and CdS
MHP and CdS
MHP and CdS-
-
-
-MHPINS to the sigmoidal Boltzmann
MHPINS to the sigmoidal Boltzmann
function
function
function
function

S13
Figure S4. Results of fitting the optical spectra of (a) CdS (b) CdS-MHP and (c) CdS-MHPINS to the
sigmoidal Boltzmann function.
S2.
S2.
S2.
S2.3
3
3
3 FDTD electromagnetic simulation
FDTD electromagnetic simulation
Figure S5. FDTD electrodynamic simulation schematic showing incident field direction (along blue
arrow), electric field polarization direction (along pink arrow) and different plane locations (yellow
rectangles) for electric field intensity distribution calculations. The nanowire is oriented vertically on an
FTO substrate. The horizontal rectangle visible at the bottom of the nanowire is the substrate.

S14
Figure S6. FDTD electrodynamic simulation results for bare CdS nanowire of 200 nm length and 50 nm
diameter. (a) Optical spectra (absorption, scattering and extinction). (b), (c) and (d) Electric field intensity
distribution along xy, xz and yz planes respectively. The electric field polarization direction is along the
z-axis in each case and have been indicated by yellow arrows. The nanowire is oriented vertically on an
FTO substrate. The horizontal rectangle visible in the plots (c & d) is the substrate.

S15
Figure S7. FDTD electrodynamic simulation results for bare CdS nanowire of 1000 nm length and 50 nm
diameter. (a) Optical spectra (absorption, scattering and extinction). (b), (c) and (d) Electric field intensity
distribution along xy, xz and yz planes respectively. The electric field polarization direction is along the
z-axis in each case and have been indicated by yellow arrows. The nanowire is oriented vertically on an
FTO substrate. The horizontal rectangle visible in the plots (c & d) is the substrate.

S16
Figure S8. FDTD electrodynamic simulation results for bare CdS nanowire of 1000 nm length and 100
nm diameter. (a) Optical spectra (absorption, scattering and extinction). (b), (c) and (d) Electric field
intensity distribution along xy, xz and yz planes respectively. The electric field polarization direction is
along the z-axis in each case and have been indicated by yellow arrows. The nanowire is oriented vertically
on an FTO substrate. The horizontal rectangle visible in the plots (c & d) is the substrate.

S17
S2.
S2.
S2.
S2.4
4
4
4 XPS valence band spectra of pristine bulk CdS, bulk C3N5 and C3N5 nanosheets
XPS valence band spectra of pristine bulk CdS, bulk C3N5 and C3N5 nanosheets
Figure S9. XPS valence band spectra of (a) C3N5 bulk and C3N5 NS and (b) pristine CdS for determining
energy levels.
S2.
S2.
S2.
S2.5
5
5
5 Band gap extraction from UV
Band gap extraction from UV
Band gap extraction from UV
Band gap extraction from UV-
-
-
-vis spectra using Kubelka
vis spectra using Kubelka
vis spectra using Kubelka
vis spectra using Kubelka-
-
-
-Munk formula
Munk formula
Munk formula
Munk formula
Figure S10. Kubelka-Munk function applied to DRS absorption data for the determination of the effective
optical bandgaps of (a) indirect bandgap semiconductor C3N5 and (b) direct bandgap semiconductor CdS
and its heterojunctions.

S18
S2.
S2.
S2.
S2.6
6
6
6 U
U
U
UPS
PS
PS
PS work function
work function
work function
work function of pristine bulk CdS
of pristine bulk CdS
of pristine bulk CdS
of pristine bulk CdS and
and
and
and C
C
C
C3
3
3
3N
N
N
N5
5
5
5 nanosheets
nanosheets
nanosheets
nanosheets
Figure S11. UPS work function of (a) bare CdS and (b) C3N5 NS for the determination of energy levels.

S19
S2.
S2.
S2.
S2.7
7
7
7 1H magic angle spinning NMR spectra
1H magic angle spinning NMR spectra
Figure S12. (a) 1
H MAS NMR spectra of (a) pristine CdS, (b) CdS-MHP, (c) CdS-MHPINS, and (d)
pristine C3N5. Spectra were obtained at a spinning frequency of 14 kHz at 9.4 T, except for the spectrum
for C3N5, which was acquired at 11.75 T with a spinning frequency of 12 kHz.

S20
S2.
S2.
S2.
S2.8
8
8
8 TRTS schematics
TRTS schematics
TRTS schematics
TRTS schematics
Figure S13. TRTS of CdS nanowires and heterojunctions. (a) Schematic of TRTS. The 410nm pump
pulse arrives at the sample a time (tpp) before the incident THz pulse (orange), inducing transient a charge
carrier population that is sampled by the THz pulse. The transmitted pulse under photoexcitation is shown
as magenta, and the reference pulse measured with no excitation is shown in green. (b) Measured reference
and photoexcited THz waveforms, with amplitude spectrum inset.

S21
S2.
S2.
S2.
S2.9
9
9
9 Steady
Steady
Steady
Steady-
-
-
-state photoconductivity plots of CdS, CdS
state photoconductivity plots of CdS, CdS
state photoconductivity plots of CdS, CdS
state photoconductivity plots of CdS, CdS-
-
-
-MHP and CdS
MHP and CdS
MHP and CdS
MHP and CdS-
-
-
-M
M
M
MHPINS
HPINS
HPINS
HPINS
Figure S14. Steady state photoconductivity plots on a log-scale for (a) Pristine CdS, (b) CdS-MHP and
(c) CdS-MHPINS samples. The measurements were carried out in the dark under AM1.5 G illumination
at 100 mW cm−2
.
S2.
S2.
S2.
S2.10
10
10
10 Rhodamine B photodegradation spectra in the presence of active species trapping agents
Rhodamine B photodegradation spectra in the presence of active species trapping agents
Figure S15. RhB degradation performance of bare CdS nanowires under AM1.5G one sun simulated
sunlight (a) With no scavenger added to the solution (b) With AgNO3 electron scavenger added to the
solution and (c) With EDTA hole scavenger added to the solution. None of the spectra show blueshifts in
the dye absorption maxima with time.

S22
Figure S16. RhB degradation performance of C3N5 wrapped CdS nanowires (CdS-MHP) under AM1.5G
one sun simulated sunlight (a) With no scavenger added to the solution (b) With AgNO3 electron
scavenger added to the solution and (c) With EDTA hole scavenger added to the solution. The spectra in
(a) show a pronounced blueshift of the dye absorption maxima with time while (b) and (c) do not show
this shift.
Figure S17. RhB degradation performance of CdS nanowires grown in the presence of C3N5 nanosheets
(CdS-MHPINS) under AM1.5G one sun simulated sunlight (a) With no scavenger added to the solution
(b) With AgNO3 electron scavenger added to the solution and (c) With EDTA hole scavenger added to
the solution. The spectra in (a) and (c) show pronounced blueshifts of the dye absorption maxima with
time while (b) does not show a blueshift.
Figure S18. Scavenger test in RhB degradation experiment for pristine CdS, CdS-MHP and CdS-
MHPINS samples with (a) AgNO3 as electron scavenger and (b) EDTA as hole scavenger.

S23
Figure S19. X-Ray diffractograms of three powder samples obtained by drying the aqueous solutions
containing RhB, AgNO3 and the photocatalyst for (a) bare CdS nanowires, (b) CdS-MHP and (c) CdS-
MHPINS following one hour illumination under AM1.5G one sun simulated sunlight.
Figure S20. RhB degradation performance of bare CdS nanowires under AM1.5G one sun simulated
sunlight (a) with IPA added to the solution and (b) with ascorbic acid added to the solution.

S24
Figure S21. RhB degradation performance of C3N5 wrapped CdS nanowires (CdS-MHP) under
AM1.5G one sun simulated sunlight (a) with IPA added to the solution and (b) with ascorbic acid added
to the solution.
Figure S22. RhB degradation performance of CdS nanowires grown in the presence of C3N5 nanosheets
(CdS-MHPINS) (a) with IPA added to the solution and (b) with ascorbic acid added to the solution.

S25
S2.
S2.
S2.
S2.11
11
11
11 Infrared spectra
Infrared spectra
Infrared spectra
Infrared spectra
Figure S23. FTIR spectra of bare C3N5 nanosheets, bare RhB and three photocatalysts emerged in RhB
solution followed by washing and drying.

S26
S2.
S2.
S2.
S2.12
12
12
12 Steady state
Steady state
Steady state
Steady state PL spectra
PL spectra
PL spectra
PL spectra in aqueous RhB solution
in aqueous RhB solution
Figure S24. Steady state photoluminescence spectra of bare RhB and three photocatalysts emerged in
aqueous RhB solution. The excitation wavelength was 470 nm.

S27
S2.
S2.
S2.
S2.13
13
13
13 Reusability test of photocatalysts for
Reusability test of photocatalysts for
Reusability test of photocatalysts for
Reusability test of photocatalysts for Rhodamine B photodegradation
Rhodamine B photodegradation
Figure S25. RhB degradation performance of reused samples under AM1.5G one sun simulated sunlight
with no scavenger added to the solution. (a) bare CdS nanowires, (b) CdS-MHP and (c) CdS-MHPINS.

S28
S2.14 4
S2.14 4
S2.14 4
S2.14 4-
-
-
-nitrophenol photodegradation data
nitrophenol photodegradation data
Figure S26. Photocatalytic test involving 4-nitrophenol degradation experiments for pristine CdS, CdS-
MHP and CdS-MHPINS samples. Comparative gradual decrease of UV-Vis absorption peak intensity
with respect to time at (a) 317 nm and (b) 400 nm.

S29
Figure S27. HPLC chromatograms during the photocatalysis of 4-nitrophenol by three photocatalysts,
showing the intermediate products of reactions after 40 minutes of light illumination.

S30
Figure S28. Negative-ion mass spectra of the peaks in the HPLC chromatograms in Figure S27.

S31
S2.
S2.
S2.
S2.15
15
15
15 Nitrogen adsorption
Nitrogen adsorption
Nitrogen adsorption
Nitrogen adsorption-
-
-
-desorption isotherm
desorption isotherm
desorption isotherm
desorption isotherm for pristine bulk CdS, CdS
for pristine bulk CdS, CdS
for pristine bulk CdS, CdS
for pristine bulk CdS, CdS-
-
-
-MHP and CdS
MHP and CdS
MHP and CdS
MHP and CdS-
-
-
-MHPINS
MHPINS
MHPINS
MHPINS
Figure S29. N2 adsorption-desorption isotherms of (a) pristine CdS, (b) CdS-MHP and (c) CdS-MHPINS
samples.

S32
S2.
S2.
S2.
S2.16
16
16
16 DFT Optimized structures for CdS
DFT Optimized structures for CdS
DFT Optimized structures for CdS
DFT Optimized structures for CdS-
-
-
-C3N5 heterojunctions
C3N5 heterojunctions
Figure S30. Top view of DFT optimized structures for heterojunctions comprised of two different CdS
planes and single-layer C3N5. (a) Configuration I for CdS (100) plane and single-layer C3N5, (b)
Configuration II for CdS (100) plane and single-layer C3N5, (c) Configuration I for CdS (110) plane and
single-layer C3N5 and (d) Configuration II for CdS (110) plane and single-layer C3N5. Cd, S, C and N
atoms are in wine, yellow, grey and blue colours respectively.

S33
S2.
S2.
S2.
S2.17
17
17
17 DFT
DFT
DFT
DFT calculated electron density difference isosurfaces
calculated electron density difference isosurfaces
calculated electron density difference isosurfaces
calculated electron density difference isosurfaces for CdS
for CdS
for CdS
for CdS-
-
-
-C3N5 heterojunctions
Figure S31. Electron density difference isosurfaces of CdS (100) plane and single-layer C3N5. (a) Side
view of configuration I, (b) side view of configuration II, (c) top view of configuration I, (d) top view of
configuration II. The pink and green colored surfaces represent charge depletion and accumulation
regions, respectively. Cd, S, C and N atoms are in wine, yellow, grey and blue colours respectively.

S34
S2.1
S2.1
S2.1
S2.18
8
8
8 DFT calculated
DFT calculated
DFT calculated
DFT calculated HOMO
HOMO
HOMO
HOMO-
-
-
-LUMO plots
LUMO plots
LUMO plots
LUMO plots for
for
for
for bare
bare
bare
bare CdS
CdS
CdS
CdS and single layer bare
and single layer bare
and single layer bare
and single layer bare C3N5
C3N5
C3N5
C3N5
Figure S32. Side view of DFT optimized structures showing spatial distributions of molecular orbitals
(HOMO-LUMO plots) for (a) Bare CdS (100) plane, (b) Bare CdS (110) plane and (c) Single-layer C3N5.
Cyan and magenta colors are for HOMO and LUMO surfaces respectively. Cd, S, C, and N atoms are in
wine, yellow, grey and blue colours respectively.

S35
S2.19 DFT calculated orbital
S2.19 DFT calculated orbital-
-
-
-resolved PDOS spectra for bare CdS
resolved PDOS spectra for bare CdS
Figure S33. Projected density of states (PDOS) of selected Cd and S atoms for pristine CdS, showing
contributions from different orbitals. (a) Cd atom on CdS (100) plane, (b) S atom on CdS (100) plane, (c)
Cd atom on CdS (110) plane and (d) S atom on CdS (110) plane.

S36
S3. Supplementary Tables
S3.
S3.
S3.
S3.1
1
1
1 Zeta potential
Zeta potential
Zeta potential
Zeta potential in aqueous
in aqueous
in aqueous
in aqueous medium
medium
medium
medium
Table S1. Calculated values of zeta potential and electrophoretic mobility in water.
S3.2 Crystallite size and
S3.2 Crystallite size and microstrain
microstrain
microstrain
microstrain
Table S2. Average crystallite size and microstrain values extracted from peak width in XRD patterns in Figure 2a
Average crystallite size (nm) Microstrain (10-4
)
hkl (100) hkl (101) hkl (110) hkl (103) hkl (100) hkl (101) hkl (110) hkl (103)
CdS 23.9 24.1 23.1 24.9 67.2 58.9 40.2 34.3
CdS-
MHP
23.9 24.1 23.1 24.3 67.2 58.9 40.2 35.3
CdS-
MHPINS
16.3 12.8 16.5 14.3 98.8 111.0 56.5 59.8
Zeta potential
(mV)
Electrophoretic
mobility
(µmcm/Vs)
CdS -6.2 -0.485
CdS-MHP 12.3 0.964
CdS-MHPINS 4.7 0.369
C3N5 NS 40.5 3.180

S37
S
S
S
S3
3
3
3.
.
.
.3
3
3
3 T
T
T
Terahertz photoconductivity
erahertz photoconductivity
erahertz photoconductivity
erahertz photoconductivity and decay
and decay
and decay
and decay data
data
data
data
Time-resolved terahertz (THz) spectroscopy (TRTS) has been used extensively to explore carrier
dynamics in nanoscale systems,12-17
and is shedding new light on the carrier dynamics in materials used
for photocatalysis.18-21
There are only a few reports available in the literature where TRTS has been
employed to extract transport parameters of CdS based nanostructures.12-16, 22
Table S3. Experimental values obtained from TRTS following Drude-Smith and biexponential fittings of conductivity
spectra and decay plots respectively.
S
S
S
S3.4
3.4
3.4
3.4 Fit parameters for terahertz photoconductivity data
Fit parameters for terahertz photoconductivity data
Table S4. Calculated values of relative weights, obtained from coefficients of a biexponential model.
tpp µNW(1+c) µNW c τDS A3 τ1 τ2 A1 A2
(ps) (cm2
/Vs) (cm2
/Vs) (unitless) (fs) (%) (ps) (ps) (%) (%)
CdS
14 40±3 420±50 -0.905±0.009 55±1
4.73±0.04 53±2 252±13 3.0±0.1 3.6±0.1
154 41±3 430±41 -0.905±0.007 56±1
CdS-MHP
14 19±4 461±155 -0.96±0.01 60±1
3.5±0.3 87±3 500±100 4.7±0.2 3.2±0.1
154 21±5 498±160 -0.96±0.01 65±1
CdS-
MHPINS
14 8.1±0.3 137±7 -0.941±0.002 17.9±0.7
0.735±0.005 9.6±0.4 150±5 1.32±0.02 0.69±0.01
154 5.1±0.2 146±8 -0.965±0.002 19.1±0.5
W1
(%)
W2
(%)
W3
(%)
CdS 27 32 42
CdS-MHP 41 28 31
CdS-MHPINS 48 25 27

S38
S
S
S
S3.5
3.5
3.5
3.5 BET
BET
BET
BET surface area, pore volume and pore size
surface area, pore volume and pore size
surface area, pore volume and pore size
surface area, pore volume and pore size from N2 adsorption
from N2 adsorption
from N2 adsorption
from N2 adsorption-
-
-
-desorption isotherm
desorption isotherm
desorption isotherm
desorption isotherm
Table S5. Calculated values of BET surface area, pore volume and pore size.
S
S
S
S4
4
4
4.
.
.
. References
References
References
References
1. Zanatta, A. R., Revisiting the Optical Bandgap of Semiconductors and the Proposal of a Unified
Methodology to its Determination. Scientific Reports 2019, 9 (1), 11225.
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Decoupling in Rotating Solids. The Journal of Chemical Physics 1995, 103 (16), 6951-6958.
3. Earl, W. L.; Vanderhart, D. L., Measurement of 13C Chemical Shifts in Solids. Journal of
Magnetic Resonance (1969) 1982, 48 (1), 35-54.
4. Treharne, R. E.; Seymour-Pierce, A.; Durose, K.; Hutchings, K.; Roncallo, S.; Lane, D., Optical
Design and Fabrication of Fully Sputtered CdTe/CdS Solar Cells. Journal of Physics: Conference Series
2011, 286.
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Highly Fluorescent Carbon Dots. ACS Appl Mater Interfaces 2017, 9 (34), 28930-28938.
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Cui, K.; Bernard, G. M.; Michaelis, V. K.; Shankar, K., Noble Metal Free, Visible Light Driven
Photocatalysis Using TiO2 Nanotube Arrays Sensitized by P-Doped C3N4 Quantum Dots. Advanced
Optical Materials 2019, 8 (4).
7. Bachelet, G.; Hamann, D.; Schlüter, M., Pseudopotentials That Work: From H to Pu. Physical
Review B 1982, 26 (8), 4199.
8. Ozaki, T., Variationally Optimized Atomic Orbitals For Large-Scale Electronic Structures. Physical
Review B 2003, 67 (15), 155108.
9. Perdew, J. P.; Burke, K.; Ernzerhof, M., Generalized Gradient Approximation Made Simple.
Physical review letters 1996, 77 (18), 3865.
10. Grimme, S., Semiempirical GGA-Type Density Functional Constructed With a Long-Range
Dispersion Correction. Journal of computational chemistry 2006, 27 (15), 1787-1799.
11. Kumar, P.; Vahidzadeh, E.; Thakur, U. K.; Kar, P.; Alam, K. M.; Goswami, A.; Mahdi, N.; Cui, K.;
Bernard, G. M.; Michaelis, V. K.; Shankar, K., C3N5: A Low Bandgap Semiconductor Containing an Azo-
Surface area
(m2/g)
Total pore volume
(cc/g)
Average pore size
(nm)
CdS 12.76 0.039 19.14
CdS-MHP 23.20 0.087 16.69
CdS-MHPINS 23.57 0.081 16.70

S39
Linked Carbon Nitride Framework for Photocatalytic, Photovoltaic and Adsorbent Applications. J Am
Chem Soc 2019, 141 (13), 5415-5436.
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in CdSxSe1–x Nanobelts: An Insight into Carrier Relaxation Dynamics via Optical Pump–Terahertz Probe
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