.

1. Accepted Article
01/2020
Accepted Article
Title: Proton-Functionalized Graphitic Carbon Nitride for Efficient Metal-
Free Disinfection of Escherichia Coli under Low-Power Light
Irradiation
Authors: Boon-Junn Ng, Muhammad Khosyi Musyaffa, Chen-Chen Er,
Kulandai Arockia Rajesh Packiam, W. P. Cathie Lee, Lling-
Lling Tan, Hing Wah Lee, Chien Wei Ooi, and Siang-Piao
Chai
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.202004238
Link to VoR: https://doi.org/10.1002/chem.202004238

2. FULL PAPER
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Proton-Functionalized Graphitic Carbon Nitride for Efficient
Metal-Free Disinfection of Escherichia Coli under Low-Power
Light Irradiation
Boon-Junn Ng,[a]
Muhammad Khosyi Musyaffa,[a]
Chen-Chen Er,[a]
Kulandai Arockia Rajesh Packiam,[a]
W. P. Cathie Lee,[b]
Lling-Lling Tan,[a]
Hing Wah Lee,[c]
Chien Wei Ooi,[a]
and Siang-Piao Chai*[a]
[a] Dr. B.-J. Ng, M. K. Musyaffa, C.-C. Er, K. A. R. Packiam, Dr. L.-L. Tan, Dr. C. W. Ooi, Prof. S.-P. Chai
Multidisciplinary Platform of Advanced Engineering, Chemical Engineering Discipline, School of Engineering
Monash University
Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia
E-mail: chai.siang.piao@monash.edu
[b] Dr. W. P. C. Lee
Entropic Interface Group, Engineering Product Development
Singapore University of Technology and Design
487372 Singapore
[c] Dr. H. W. Lee
Nanoelectronics Lab
Mimos Berhad
Technology Park Malaysia, Kuala Lumpur 57000, Malaysia
Supporting information for this article is given via a link at the end of the document.
Abstract: Universal access to clean water has been the global
ambition over the years. Photocatalytic water disinfection via
advanced oxidation processes has been regarded as one of the
promising methods in breaking down microbials. The forefront of this
research focuses on the application of metal-free photocatalysts for
disinfection to prevent secondary pollution. Graphitic carbon nitride
(g-C3N4) has achieved instant notoriety as a metal-free and visible-
light-responsive photocatalyst for various energy and environmental
applications. However, the efficiency of g-C3N4 in photocatalysis is
still affected by its rapid charge recombination and sluggish electron
transfer kinetics. In this contribution, two-dimensional protonated g-
C3N4 was employed as metal-free photocatalyst for water treatment
and demonstrated 100% disinfection of Escherichia coli within 4 h
under 23 W light bulb irradiation. The introduction of protonation can
modulate the surface charge of g-C3N4 which enhance its
conductivity and provide a “highway” for the delocalization of
electrons. This work highlights the potential of conjugated polymer in
antibacterial application.
Introduction
The onslaught of water scarcity is becoming more apparent on a
worldwide scale owing to the rapid growth in population and
heavy industrialization. Statistically, 3.4 million deaths annually
are associated with water-related diseases.[1]
Therefore, the
issue of water contamination with microorganisms and other
organic pollutants is a growing concern. Up to now, several
disinfection technologies such as chlorination, ozonation and UV
irradiation have been effective in deactivating microbial
pathogens.[2]
However, the conventional chemical oxidation
approach tends to produce harmful disinfection by-products that
are potentially carcinogenic, for instance, trihalomethane.[3]
This
prompts a debatable argument on the effective disinfection vs.
by-product formation dilemma. Besides, the disinfection
efficiency of UV irradiation method is low against some UV
resistant microbials. Hence, the development of a stable, non-
toxic and efficient disinfection strategy is imperative to solve the
water crisis.
The ground-breaking discovery of photocatalytic
disinfection of microbial cells via advanced oxidation
processes (AOPs) was firstly demonstrated by Matsunaga
et al. in 1985.[4]
The fundamental rationales of AOPs are
established on the formation of highly reactive oxidative
species (●
OH, ●
O2
−
, H2O2 etc.) to break down or mineralize
complex organic compounds and microbial pathogens.[5]
In
this context, heterogenous photocatalysis which generally
employs semiconductor with suitable band structure could
provide a platform for the in-situ generation of reactive
species via redox reaction upon irradiation. As compared to
the conventional disinfection approaches, photocatalysis
confers several prominent features which include ambient
operating condition, low cost and minimal secondary
environmental pollution.
For years, photocatalytic disinfection studies primarily
focus on the implication of TiO2 attributed to its
photocatalytic stability, suitable valance band (VB) edge for
strong oxidation, environmental benignity and cost
effectiveness.[6]
However, TiO2 is only active under UV
irradiation which corresponds to 4% of the incoming solar
spectrum. Hitherto, progressive research endeavours have
been devoted to developing visible-light-active
photocatalysts with high water disinfection efficiency, for
instance, loading of noble metal co-catalysts (Pt, Ag and
Cu),[7-9]
doping of cations (Fe3+
and Cu2+
)[10, 11]
and
semiconductors coupling to form heterojunction (TiO2-
10.1002/chem.202004238
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Figure 1. Synthesis protocol of protonated g-C3N4 (P-CN) from: (a) precursor melamine, (b) thermal polymerization into bulk g-C3N4, (c) thermal annealing in N2
and acid treatment into P-CN and (d) representative FESEM image of P-CN (scale bar: 1 µm).
BiWO6)[12]
and Z-scheme composites (AgBr-Ag-ZnFe2O4
and TiO2-rGO-WO3).[13, 14]
However, cutting edge research
of photocatalytic disinfection emphasizes on the application
of metal-free photocatalysts to avoid secondary pollution.
Two-dimensional (2D) graphitic carbon nitride (g-C3N4)
has proliferate its research profile in environmental and
energy applications ascribed to the appealing properties:
(1) facile synthesis method from inexpensive precursors,
i.e. urea, dicyandiamide and melamine, (2) visible light
responsive, (3) suitable band structure with strong redox
ability and (4) high chemical stability.[15-17]
Even so, the
photocatalytic performance of g-C3N4 is still plagued by its
rapid recombination of charge carriers and sluggish
electron transfer kinetics. Herein, we report the synthesis of
proton-functionalized g-C3N4 nanosheets (P-CN) via two-
step thermal annealing with post acid treatment. The
introduction of H+
into the lattice of g-C3N4 can enhance its
conductivity and provide a “highway” for the delocalization
of electrons. Besides, the presence of H+
in g-C3N4
nanosheets can reduce charge transfer resistance and
suppress recombination of electron-hole pairs. In stark
comparison to the low activity of g-C3N4 nanosheets without
protonation (CN), P-CN demonstrated 100% disinfection of
Escherichia coli (E. coli) within 4 h under 23 W low power
household light bulb irradiation. On top of that, the presence
of reactive oxygen species (ROS) was quantified via
scavengers testing and a plausible disinfection mechanism
was postulated. This finding suggests an avenue for
microbial disinfection using visible-light-active metal-free
photocatalyst.
Results and Discussion
Synthesis protocol and structure characterization
The synthesis protocol of P-CN is schematically illustrated in in
Figure 1. Typically, bulk g-C3N4 was firstly synthesized from
melamine via thermal oxidation. Further annealing of bulk g-
C3N4 in N2 resulted in the formation of g-C3N4 nanosheets (CN)
with negative surface charge. Attributed to the presence of -C-N-
motifs in the framework of g-C3N4, surface charge of CN sample
can be easily modulated using HNO3. Protonation of CN into P-
CN was done by post acid treatment, in which the surface
charge turned positive due to the introduction of H+
. As shown in
Figure S1, the zeta potential of P-CN dispersion in water was
measured to be +35.0 mV while CN conferred negative surface
charge (-27.1 mV), proving the successful protonation of g-C3N4.
The surface morphology and microstructures of P-CN were
investigated using FESEM. As depicted in Figure 1d, P-CN
displayed a 2D layered structure with a lateral scale of several
micrometers. Besides, the sheet-like P-CN displayed obvious
hierarchical edges with less bulk domains.
The phase structures of CN and P-CN were then
investigated via XRD analysis. It can be observed that there are
two apparent XRD diffraction peaks at 13.2° and 27.4° for both
CN and P-CN, which can be well indexed to be (100) and (002)
planes of g-C3N4 (Figure 2a). The peak at 13.2° with lower
intensity corresponds to the tri-s-triazine units while the higher
peak at 27.4° is the interplanar stacking aromatic system of g-
C3N4.[18]
This indicates that the structure of g-C3N4 was
preserved after protonation. Besides, the XRD peak intensity of
P-CN is slightly lower than CN, attributed to the exfoliation of g-
C3N4 after acid treatment. Furthermore, the structural information
of the samples was reaffirmed by FTIR measurement, as
depicted in Figure 2b. Both CN and P-CN rendered nearly
identical FTIR characteristics peaks, indicating that the
protonation did not demolish the in-plane tri-s-triazine units of g-
C3N4. The sharp band located at ca. 810 cm-1
is characteristic to
the breathing mode of tri-s-triazine ring, while the strong
absorption peaks observed within the range of 1200-1700 cm-1
are the stretching and bending nodes of the C-N heterocycles
which comprised of fully condensed trigonal units (N-(C)3) and
partially condensed bridging C-NH-C units. This suggests the
successful formation of the extended C-N-C network in g-C3N4.
Additionally, the high resolution N 1s XPS spectra of P-CN can
be deconvoluted into four peaks (Figure S2). The presence of
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weak peak at ca. 404.2 eV is associated to the successful
protonation of g-C3N4.[19, 20]
This indicates that the heterocycles
of P-CN were positively charged, which is in well agreement with
the result from zeta potential measurement. The dominant peaks
at 398.4 and 399.6 eV are characteristic to the sp2
-bonded N
atoms in the triazine units (C-N=C) and the bridging N atoms in
N-(C)3. Whereas the peak at 400.9 eV is indexed as the terminal
amino groups owing to the incomplete condensation during
thermal polymerization reaction.
Photocatalytic disinfection experiment
The photocatalytic disinfection performance of the samples was
evaluated using E. coli as the model microbial. A simple
screening study was carried out to determine an appropriate cell
concentration for use in the disinfection experiments. According
to Figure S3, the spread agar plates with initial concentration of
1 × 107
, 1 × 106
and 1 × 105
cells/mL did not yield a countable
number of colony-forming unit (CFU). Hence, a dilution factor of
1/50 was included into spread agar plate with 1 × 105
cells/mL,
which yielded a countable 180 CFU (Figure S3d). This resultant
spread agar plate was then selected for all the disinfection runs.
Prior to the experiment, a dark control experiment was
conducted using the cell suspension with photocatalyst. In the
absence of irradiation, the reduction of E. coli was minimal even
after 30 min, indicating the non-toxicity of samples towards the
microbials.
Figure 2. (a) XRD spectra and (b) FTIR spectra of CN and P-CN.
Figure 3a shows the dependency of E. coli disinfection
efficiency on the effect of photocatalyst concentration of P-
CN under 18 W light bulb irradiation. It can be observed
that the disinfection efficiency of E. coli increases with the
concentration of P-CN. However, the disinfection efficiency
of P-CN with concentration of 1.0 mg/mL (95.74%) and 1.5
mg/mL (97.56%) are very close. This suggests that P-CN at
1.0 mg/mL is enough for a decent performance of E. coli
disinfection. Hence, the subsequent experimental runs were
performed using P-CN with concentration of 1.0 mg/mL. On
top of that, CN was employed as control sample during the
experiment. Comparatively, P-CN is much efficient than CN
in the antibacterial activity. This is ascribed to the
accelerated electron transfer and localization in P-CN with
the presence of H+
. The time courses of photocatalytic
disinfection of E. coli by P-CN and CN are shown in Figure
S4a. Besides, inset of Figure 3a delineates the images of
bacterial CFU of re-cultured E. coli after photocatalytic
disinfection by 1.0 mg/mL P-CN over 240 min (4 h). The
stark reduction in CFU of re-cultured E. coli over time
demonstrated the effectiveness of metal-free P-CN in
photocatalytic disinfection. In order to achieve total
disinfection of E. coli, P-CN with concentration of 1.0
mg/mL was subjected to disinfection experiment under
different light power (Figure 3b and S4b). It was found that
P-CN exhibited 100% disinfection of E. coli under 23 W low
power energy saving light bulb irradiation after 4 h. A
comparison of photocatalytic E. coli disinfection
performance of this study with other reported works is
tabulated in Table S1. Most of the reported g-C3N4 work
uses metal co-catalysts or forming heterojunction with
metal-based photocatalysts. On the contrary, our study
provides a metal-free pathway for antibacterial application
which renders excellent disinfection performance even
without the use of co-catalyst. Besides, P-CN in this work is
able to achieve total disinfection under low power light
irradiation in 4 h as compared to the reported porous g-
C3N4 that employed 500 W Xe lamp. Thus, this work offers
a feasible approach for metal-free photocatalytic
disinfection under household light irradiation.
To gain a deeper understanding on the photocatalytic
disinfection mechanism, a series of scavengers were used
individually to quench the reactive species produced by P-
CN. In this context, isopropanol (IPA) was employed to
capture ●
OH while ascorbic acid (AA) and
ethylenediaminetetraacetic acid (EDTA) were applied for
superoxide (●
O2
−
) and holes (h+
), respectively. Figure 3c
shows that ●
O2
−
plays a minimal role in the antibacterial
process as P-CN rendered similar photocatalytic
disinfection efficiencies with and without AA. On the other
hand, when IPA and EDTA were used to consume ●
OH and
h+
, the photocatalytic E. coli disinfection performance was
greatly inhibited. This indicates that oxidation process of P-
CN is dominant in E. coli disinfection via ●
OH and h+
radicals.
Figure 3. (a) Dependency of overall E. coli disinfection efficiency on the effect
of photocatalyst concentration for P-CN after 240 min under 18 W low power,
energy saving light bulb. Inset showing the bacterial CFU of re-cultured E. coli
after photocatalytic disinfection by 1.0 mg/mL P-CN over 240 min. (b)
Dependency of overall E. coli disinfection efficiency on the effect of irradiation
power using 1.0 mg/mL of P-CN after 240 min. (c) Effect of different
scavengers on photocatalytic disinfection of E. coli by 1.0 mg/mL P-CN.
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Insights on band structure and charge transfer mechanism
The optical properties of the samples were then investigated
using UV-Vis DRS. As shown in Figure 4a, the absorption edges
of P-CN and CN were determined to be 458 and 464 nm,
respectively. The slight blue-shifting of absorption profile of g-
C3N4 after protonation can be ascribed to the reduction in
thickness of material. Correspondingly, the band gap values of
P-CN and CN were measured to be 2.71 eV and 2.67 eV, as
depicted from the Kubelka-Munk (KM) function in Figure 4b. This
is in well agreement with the PL analysis shown in Figure 4c, in
which the emission peak of P-CN is slightly blue-shifted as
compared to CN. Besides, P-CN conferred lower PL emission
peak as compared to CN, indicating a more suppressed
recombination of electron-hole pairs.
Figure 4. (a) UV-Vis DRS, (b) plot of transformed KM function, (c) PL spectra
and (d) EIS Nyquist plots of CN and P-CN. (e) Proposed electron/hole transfer
mechanism for P-CN in photocatalytic disinfection of E. coli.
Furthermore, the charge transfer behaviors of the samples
were examined using transient photocurrent responses and EIS
Nyquist plots. In general, transient photocurrent responses are
measured via the signal from the back diffusion of electrons and
the simultaneous update of holes by the electrolyte.[21-24]
Figure
S5 delineates a distinct improvement in the photocurrent density
of P-CN as compared to CN under intermittent illumination.
Besides, the photocurrent stability of P-CN is depicted in Figure
S6. On the other hand, the smaller arc radius of EIS Nyquist
plot of P-CN reflects the facilitated charge transfer in the sample
after protonation with more suppressed interfacial layer
resistance (Figure 4d). The plausible charge transfer mechanism
of P-CN is illustrated in Figure 4e. The presence of H+
groups in
P-CN can facilitate electron transfer and promote delocalization
of charges, which in turn produce more reactive species for the
efficient disinfection of E. coli.
To determine the influence of protonation on g-C3N4 in
affecting the photocatalytic performance, DFT simulation was
obtained and depicted in Figure 5. According to the partial
density of states (PDOS) of P-CN in Figure 5d, the conduction
band (CB) is comprised of C 2p, N 2p and H. The comparison of
total density of states (TDOS) shown in Figure 5e indicates that
both P-CN and CN confer nearly similar band position. It can be
observed that the CB edge of P-CN is slightly shifted down in
energy. Besides, P-CN is slightly blue shifted (band gap: 2.84
eV) as compared to CN (band gap: 2.7 eV) according to Figure
5e, which correlates with the experimental findings.
Furthermore, P-CN experienced slight distortion in the heptazine
lattice structure as compared to CN due to the redistribution of
electrons (Figure 5a and Figure 5b). As disclosed in the charge
density distribution plot in Figure 5c, it can be visualized that the
distribution of electrons is heterogenous, i.e. localization of
electrons around H atoms. Thus, P-CN renders facilitated
charge transfer and efficient charge isolation after protonation.
Figure 5. Optimized geometries of (a) CN and (b) P-CN. (c) Charge density
distribution of P-CN. (d) Density of states for P-CN. (e) Comparison of total
density of states for P-CN and CN. The dashed line represents the Fermi level
which was set to 0 eV.
Conclusions
In summary, this work successfully demonstrated a total
disinfection of E. coli using protonated g-C3N4 in 4 h under
23 W low energy household light bulb. Protonation can
provide a modulation on the electronic properties of g-C3N4
and improve their conductivity. The augmentation in
photocatalytic performance after protonation is attributed to
the facilitated charge separation which in turn produces
more active species. It is anticipated that the result will
evoke new interest in developing conductive polymers as a
metal-free photocatalyst for water disinfection.
10.1002/chem.202004238
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Experimental Section
Synthesis of bulk g-C3N4
Typically, 3 g of melamine was placed in an alumina crucible and
subjected to annealing inside a muffle furnace at 550 °C for 4 h. The
resultant yellowish powder was then collected and labelled as bulk g-
C3N4.
Synthesis of protonated g-C3N4 nanosheets (P-CN)
The as-synthesized bulk g-C3N4 was then grounded into fine powder and
subjected to second thermal annealing to produce g-C3N4 nanosheets
(CN). In brief, bulk g-C3N4 was heated in a tube furnace under N2
environment at 550 °C for 4 h. Prior to the calcination process, the tube
furnace was firstly evacuated by purging N2 gas at a high flow rate for 30
min.
To functionalize the as-prepared CN, 500 mg of the finely grounded
sample was firstly added to 50 mL of 5 M HNO3. The solution was stirred
at room temperature for 30 min to allow the dispersion of photocatalyst.
Subsequently, the solution was heated under reflux at 135 °C for 1 h.
After cooling to room temperature, the solid was collected via
centrifugation and washed with ethanol and DI water 3 times each. The
resultant powder (protonated g-C3N4 nanosheets) was dried at 70 °C in
vacuum oven and labelled as P-CN.
Materials characterization
The crystallographic properties of the samples were analyzed via X-ray
diffraction (XRD) measurement on a Bruker D8 Discover X-ray
diffractometer with Ni-filtered Cu Kα radiation at a scan rate of 0.02° s-1
.
On the other hand, the molecular structural information was obtained
from a Fourier transform infrared spectroscopy (FTIR) using Thermo-
Nicolet iS10. The surface morphology was examined by field emission
scanning electron microscopy (FESEM) via a Hitachi SU8010
microscope. Meanwhile, zeta potential measurements were taken from
dynamic light-scattering analysis using a Zetasizer Nano ZS (Malvern
Instruments). Besides, UV-Vis diffused reflectance spectrums of the
samples were obtained using a Cary 100 UV-Vis spectrophotometer
(Agilent) equipped with an integrated sphere and BaSO4 was employed
as a reflectance standard. X-ray photoelectron spectroscopy (XPS)
measurements were carried out using a scanning X-ray microprobe PHI
Quantera II (Ulvac-PHI, INC.) with monochromatic Al-Kα (hv = 1486.6
eV) X-ray source. Lastly, steady-state photoluminescence (PL) spectra
was taken from fluorescent spectrometer (Perkin Lamer LS55).
Electrochemical analysis
The electrochemical measurements (Nyquist plot and transient
photocurrent) were measured via a CHI 6005E electrochemical
workstation with a three-electrode photoelectrochemical (PEC) system.
In this system, Pt was used as the counter electrode while Ag/AgCl
saturated with 3 M KCl was utilized as the reference electrode. Besides,
1.0 M Na2SO4 aqueous solution was employed as the electrolyte. During
the measurements, the working electrode was illuminated with a lamp-to-
sample distance of 15 cm using a 500 W Xe lamp.
Calculation methods
Density Functional Theory based first principle calculation was performed
using the projector augmented wave (PAW) method as implemented in
the Vienna Ab initio Simulation Package (VASP).[25-29] The electron
exchange-correlation interactions were treated within the generalized
gradient approximation (GGA) with respect to the Perdew-Burke-
Ernzerhof (PBE) functional.[30] Hybrid functionals based on the Heyd-
Scuseria-Ernzerhof (HSE06) method were adopted to obtain more
accurate electronic properties of the CN and P-CN.[31] A plane-wave
basis set with an energy cutoff of 400 eV and a 3 × 3 × 1 (Monkhorst-
Pack grid) was used to sample the Brillouin Zone. The convergence
criterion for energy and force were set at ≤ 10-5 eV and 0.01 eV/Å,
respectively. A supercell consisting of four heptazine unit cells and three
heptazine unit cells for CN and P-CN configuration were used throughout
the calculation.
Preparation of photocatalyst-cell suspension
The photocatalyst-cell suspension was prepared according to the earlier
publication of our research group.[2] All glassware and solution were
autoclaved at 121 °C for 15 min in order to ensure sterility prior to the
experiment. First and foremost, 500 μL glycerol stock E. coli BL21 (DE3)
was inoculated into 50 mL of Luria Bertani (LB) broth which has already
been dosed with kanamycin at a dilution of 1:100. The solution was then
incubated in a shaker incubator at 37 °C for 12 h with a shaking speed of
125 rpm. The E. coli cells were then harvested via centrifugation and
washed with sterilized sodium chloride solution (0.9% NaCl).
Subsequently, the collected cells were resuspended in 40 mL of 0.9%
NaCl to obtain a suspension of 8 × 108 colony-forming unit/mL (CFU/mL).
Afterwards, 50 μL of cell suspension (8 × 108 CFU/mL) was added into
another 40 mL of 0.9% NaCl to create a suspension of 1 × 106 CFU/mL.
To prepare the photocatalyst-cell suspension (30 mL), 3 mL of E. coli
suspension (1 × 106 CFU/mL) was mixed with 27 mL of 0.9% NaCl and a
desired amount of photocatalyst to obtain a final solution with cell
concentration of 1 × 105
CFU/mL.
Photocatalytic disinfection experiment
The photocatalytic disinfection experiment was carried out in a flask
containing the photocatalyst-cell suspension irradiated by a Philips
energy saving light bulb (8W, 18W and 23 W) for 240 min under stirring.
Prior to the photocatalytic disinfection process, the suspension was
stirred in the dark for 30 min. Successively, 1 mL of the sample was
collected at an interval of 80 min. For agar plate spreading and CFU
calculation, 1 mL of the collected sample was firstly diluted with 0.9%
NaCl at a dilution factor of 1:50. The sample was then carefully spread
across the surface of agar plate. Afterwards, the agar plate was
incubated at 37 °C for 16 h. Lastly, the cell quantification was performed
via colony counting method on the agar plate.
Acknowledgements
This work was funded by the Ministry of Higher Education
(MOHE) Malaysia and Universiti Sains Malaysia under
NanoMITe-LRGS (Ref. no.: 203/PJKIMIA/670009).
Keywords: graphitic carbon nitride • protonation • water
disinfection • photocatalysis • anti-bacterial
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10.1002/chem.202004238
Accepted
Manuscript
Chemistry - A European Journal
This article is protected by copyright. All rights reserved.

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The efficiency of graphitic carbon nitride (g-C3N4) in photocatalytic water disinfection is plagued by its rapid charge recombination and
sluggish electron transfer kinetics. The introduction of protonation onto g-C3N4 can enhance its conductivity and provide a “highway”
for the delocalization of electrons. Consequently, protonated g-C3N4 demonstrated 100% disinfection of Escherichia coli within 4 h
under low power household light irradiation.
10.1002/chem.202004238
Accepted
Manuscript
Chemistry - A European Journal
This article is protected by copyright. All rights reserved.