Construction of molecularly doped and cyano defects co-modified graphitic carbon nitride for the efficient photocatalytic degradation of tetracycline hydrochloride
11 Oct 2021-New Journal of Chemistry (The Royal Society of Chemistry)-Vol. 45, Iss: 39, pp 18598-18608
TL;DR: In this paper, a co-modification of graphitic carbon nitride (g-C3N4) with 4,6-dimethyl-2-hydroxypyrimidine-doped and cyano defects was presented.
Abstract: The structural modulation of graphitic carbon nitride (g-C3N4) is regarded as an effective strategy to boost its photocatalytic behavior. Herein, we have synthesized 4,6-dimethyl-2-hydroxypyrimidine-doped and cyano defects co-modified graphitic carbon nitride (HDMP–CD-g-C3N4) using a facile in situ co-condensation method. HDMP–CD-g-C3N4 was employed for the degradation of tetracycline hydrochloride, exhibiting enhanced photocatalytic activity and catalyst stability. The characterization results demonstrate that the doping of HDMP decreases the band gap, thus promoting the light absorption of g-C3N4. Meanwhile, as an electron acceptor, HDMP broadens the π-conjugated off-domain system and accelerates the transfer of photogenerated electrons. In addition, the introduction of cyano defects further improves the separation efficiency of photogenerated electrons and holes. Analysis of time-resolved fluorescence spectra solidly supports these conclusions. Therefore, the photocatalytic degradation rate of HDMP–CD-g-C3N4 was 3.8 times that of the original g-C3N4, 2 times that of HDMP-doped g-C3N4 (HDMP-g-C3N4) and 2.5 times that of cyano defects-modified g-C3N4 (CD-g-C3N4). This work provides a way for collaboratively modulating the structure of g-C3N4 with molecular doping and defects, which is expected to bring novel prospects for the application of g-C3N4 in the treatment of waste water.
Citations
More filters
TL;DR: In this paper , a simple and safe one-step calcination method with industrial-grade micron particles CaCO3 was obtained by using nitrogen deficiency into graphite carbon nitride to solve the problem of high recombination rate of photogenerated carriers.
Abstract: Graphite carbon nitride has many excellent properties as a two-dimensional semiconductor material so that it has a wide application prospect in the field of photocatalysis. However, the traditional problems such as high recombination rate of photogenerated carriers limit its application. In this work, we introduce nitrogen deficiency into g-C3N4 to solve this problem a simple and safe in-situ reduction method. g-C3N4/CaCO3 was obtained by a simple and safe one-step calcination method with industrial-grade micron particles CaCO3. Cyano group modification was in-situ reduced during the thermal polymerization process, which would change the internal electronic structure of g-C3N4. The successful combination of g-C3N4 and CaCO3 and the introduction of cyanide have been proved by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The formation of the cyano group, an electron-absorbing group, promotes the effective separation of photogenic electron hole pairs and inhibits the recombination of photogenic carriers. These advantages result in the generation of more •O2- and 1O2 in the catalytic system, which increases the photocatalytic efficiency of nicotine degradation by ten times. Furthermore, the degradation process of nicotine has been studied in this work to provide a basis for the degradation of nicotine organic pollutants in the air.
8 citations
TL;DR: In this paper , a Schottky heterojunction was fabricated from narrow bandgap Mo-Ni bimetallic sulfide and g-C3N4 nanosheets to maximize carrier separation.
Abstract: A novel Schottky heterojunction is fabricated from narrow bandgap Mo–Ni bimetallic sulfide and g-C3N4 nanosheets to maximize carrier separation.
2 citations
TL;DR: In this article , a photo-Fenton-like coupled system was proposed, which used BiVO4 and Cu2(OH)3F as electron donor and acceptor, respectively, and achieved efficient electron transfer between them through electron bridging effect of Carbon quantum dots (CQDs).
Abstract: Herein, we report a novel Cu2(OH)3 F/CQDs-BiVO4 composite photo-Fenton-like system, which used BiVO4 and Cu2(OH)3F as electron donor and acceptor, respectively, and achieved efficient electron transfer between them through the electron bridging effect of Carbon quantum dots (CQDs). The material exhibited excellent ciprofloxacin (CIP) removal efficiency in the photo-Fenton-like coupled system. Cu2(OH)3 F/CQDs-BiVO4 had an incredibly fast response rate, eliminating 98.1% of CIP from the solution in just 1 h, according to the reaction kinetics. Exploratory tests proved that the catalyst kept up a sufficient level of activity across a wide pH range of 3-11 and in the presence of various anions. The activity, morphology, and crystal structure of the samples did not appreciably alter after five recycles. Finally, a possible reaction mechanism was also proposed based on the band structure, position and reaction species.
References
More filters
TL;DR: Water photolysis is investigated by exploiting the fact that water is transparent to visible light and cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm.
Abstract: ALTHOUGH the possibility of water photolysis has been investigated by many workers, a useful method has only now been developed. Because water is transparent to visible light it cannot be decomposed directly, but only by radiation with wavelengths shorter than 190 nm (ref. 1).
27,819 citations
TL;DR: It is shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor.
Abstract: The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.
9,751 citations
TL;DR: It is anticipated that this review can stimulate a new research doorway to facilitate the next generation of g-C3N4-based photocatalysts with ameliorated performances by harnessing the outstanding structural, electronic, and optical properties for the development of a sustainable future without environmental detriment.
Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...
5,054 citations
TL;DR: A facile synthetic strategy for nitrogen-deficient graphitic carbon nitride (g-C3 Nx) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea, with superior visible-light photocatalytic performance compared to pristine g-C2 N4.
Abstract: A facile synthetic strategy for nitrogen-deficient graphitic carbon nitride (g-C3 Nx ) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea. In situ introduced nitrogen vacancies significantly redshift the absorption edge of g-C3 Nx , with the defect concentration depending on the alkali to nitrogen precursor ratio. The g-C3 Nx products show superior visible-light photocatalytic performance compared to pristine g-C3 N4 .
1,535 citations
TL;DR: It is demonstrated that the optical absorption of carbon nitride semiconductor materials is extendable into the visible region up to about 750 nm by simple copolymerization with organic monomers like barbituric acid (BA).
Abstract: and nonmetallic elements (N, C, B) creates localized/ delocalized states in the band gap and thus extends its optical absorption to the visible region, but doping usually comes with accelerated charge recombination and lower stability of the doped materials. Meanwhile, various other inorganic, non-TiO2-based, visible-light catalysts have been developed (e.g., metal oxides, nitrides, sulfides, phosphides, and their mixed solid solutions), whereby Ga, Ge, In, Ta, Nb, and W are the main metal constituents. However, sustained utilization of solar energy calls for the development of more abundant and stable catalysts working with visible light, and this has remained challenging so far. Recently, a polymeric semiconductor on the basis of a defecteous graphitic carbon nitride (g-C3N4), was introduced as a metal-free photocatalyst which fulfills the basic requirements for a water-splitting catalyst, including being abundant, stable, and responsive to visible light. In the following, we use the notation “g-C3N4” to describe this class of materials rather than the idealized structure. The most active system is in fact presumably an N-bridged “poly(tri-s-triazine)”, already described by Liebig as “melon”. A semiconductor structure with band edges straddling the water redox potential was revealed for melon by DFT calculations, albeit electrochemical analysis is still awaited. g-C3N4 is considered to be the most stable phase of covalent carbon nitride, and facile synthesis of the melon substructure from simple liquid precursors and monomers allows easy engineering of carbon nitride materials to achieve the desired nanostructures via soft-chemical processing routes and methods. For instance, a high surface area (67–400 mg ) can be imparted on g-C3N4 materials by polymerization of cyanamide on a silica template, which results in photocatalytically more active g-C3N4 nanostructures. [8] Metal-doped gC3N4 can also be conveniently obtained by polymerization of dicyandiamine in the presence of metal salts, and thus multifunctionalization of such materials for a variety of applications can be achieved. Most importantly, the electronic and optical properties of carbon nitride, regarded as a polymer semiconductor, are in principle adjustable by organic protocols. Such organic protocols have been widely used to control the performance of traditional p-conjugated polymers, for example, to improve solar-cell efficiencies by constructing copolymerized donor–acceptor structures, or to modify electronic properties by co-blending with p/n-type organic dopants. Our aim was to use such organic modifications to extend the insufficient light absorption of g-C3N4 (a result of its large band gap of 2.7 eV, which corresponds to wavelengths shorter than 460 nm) towards the maximum of the solar spectrum. Here we demonstrate that the optical absorption of carbon nitride semiconductor materials is extendable into the visible region up to about 750 nm by simple copolymerization with organic monomers like barbituric acid (BA). The electronic and photoelectric properties of the modified carbon nitrides were then investigated to elucidate their enhanced activity for hydrogen production from water containing an appropriate sacrificial reagent with visible light. In principle, BA can be directly incorporated into the classical carbon nitride condensation scheme (Scheme 1). New carbon nitride structures were therefore synthesized by dissolving dicyandiamide with different amounts of BA in water, followed by thermally induced copolymerization at 823 K. For simplicity, the resulting samples are denoted CNBx, where x (0.05, 0.1, 0.2, 0.5, 1, 2) refers to the weighedin amount of BA. The structure, texture, and electrochemical properties of these materials were characterized, and their photochemical performance analyzed. Their XRD patterns (Figure S1, Supporting Information) are dominated by the characteristic (002) peak at 27.48 of a graphitic, layered structure with an interlayer distance of d = [*] J. Zhang, X. Chen , Prof. X. Fu, Prof. X. Wang State Key Laboratory Breeding Base of Photocatalysis Fuzhou University, Fuzhou 350002 (China) E-mail: xcwang@fzu.edu.cn
1,244 citations