Graphitic Carbon Nitride Photocatalyst Research Articles

Development of nickel doped graphitic carbon nitride (GCN) photocatalyst for enhanced degradation of textile pollutant under visible light irradiation

An efficient rare earth metal (nickel) doped graphitic carbon nitride photocatalyst is developed by a facile synthesis approach. The synthesized nickel doped graphitic carbon nitride (x-NGCN) is employed for photocatalytic degradation of organic dye methylene blue (MB) simulated textile wastewater. It is observed that Ni doping of GCN enhances the optical absorption to such an extent that it efficiently degrades the MB dye under simple LED white light (5 W), mainly consisting of visible light range. Hence Ni doping resulted in sensitivity towards visible light range of spectrum due to narrowing of bandgap, thus increasing the photocatalytic performance. The prepared photocatalysts are characterized using various spectroscopy tools to investigate the crystallinity, morphology, functional groups, optical absorption, and charge separation efficiency.

Photocatalytic Th(IV) removal: Unleashing the potential of amidoxime-modified graphitic carbon nitride photocatalyst

g-C3N4-AX photocatalyst was synthesized using a hydrothermal approach, with urea as a precursor, for the removal of Th(IV) in aqueous solution. The results of the experiment indicated that the addition of amidoxime to g-C3N4 altered its photocatalytic characteristics, resulting in a narrower band gap reduced from 2.75 eV to 2.7 eV, and faster formation of electron-hole pairs. The g-C3N4-AX photocatalyst exhibited remarkable uptake capacity with 71.09 mg.g−1 within 120 min. The excellent performance of g-C3N4-AX was mainly attribute to its effective absorption of visible light, facilitated by the narrow band gap. Therefore, this study proposes the potential of g-C3N4-AX can be efficiently adapted as a visible light-responsive catalyst for the application in radioactive effluent treatment.

A novel graphitic carbon nitride photocatalyst with ultramicro amounts of intramolecular donor-acceptor structures for excellent photocatalytic hydrogen production

In this study, facile supramolecular thermal polymerization was employed for an attempt to modify graphitic carbon nitride (g-C3N4) using ultramicro amounts of diphenylamino-4-benzaldehyde as the dopant, and melamine and cyanuric chloride as the raw materials. The reaction of aldehyde-amine achieved diphenylamino-4-benzaldehyde grafting onto the edge of the heptazine ring of g-C3N4, resulting in the formation of a novel g-C3N4 with intramolecular twisted donor–acceptor (D-A) structures known as CN-Dxmg. It was confirmed that addition of 2 mg (0.67 wt‰) of diphenylamine-4-benzaldehyde as the donor regulated the energy level distribution of CN-D2mg, and as-obtained intramolecular D-A structures can promote the photogenerated carrier separation and migration of CN-D2mg through a directional channel for electron transfer from diphenylamine-4-benzaldehyde to heptazine. The results indicate that CN-D2mg photocatalyst has a high hydrogen production rate of 14581.1 μmol·h−1·g−1 at 420 nm under visible light irradiation, which is 1.6 times higher than that of pristine g-C3N4. The study presents an effective approach for large-scale applications involving g-C3N4 photocatalyst in clean energy production.

One-pot preparation of potassium, iodine-codoped hydrophilic polymeric carbon nitride with highly efficient quasi-homogeneous photocatalytic H2O2 production

The production of hydrogen peroxide (H2O2) through visible photocatalytic molecular oxygen has gained significant attention as an environmentally friendly and sustainable approach. In this study, a unique multivariate modified graphitic carbon nitride (g-C3N4) photocatalyst is designed and successfully synthesized by incorporating K and I species as heteroatomic co-dopant, along with the defect engineering in g-C3N4. The resulting photocatalyst consists of particles ranging in size from 50 to 200 nm. Experimental results reveal that K atoms form chemical bonds with N atoms in adjacent layers, facilitating enhanced electron migration. On the other hand, I atoms predominantly localize at the edges of g-C3N4 building blocks, contributing to the formation of cyano groups (CN). These cyano groups, acting as nitrogen defects, can effectively narrow the band gap, elevate the conduction band, and effectively improve the generation and transport of photoexcited charge carriers. By precisely controlling the proportion of KI, the formation of cyanide can be effectively regulated. Notably, the obtained photocatalyst exhibits a remarkably high H2O2 yield of 4386.4 μΜ h−1 under visible light, surpassing that of g-C3N4 and other g-C3N4-based photocatalysts. This work presents a novel design strategy for the development of highly efficient photocatalysts for H2O2 production.

Cu-coated graphitic carbon nitride (Cu/CN) with ideal photocatalytic and antibacterial properties

An improved photocatalytic activity of Graphitic carbon nitride (CN) photocatalyst was achieved by incorporating Cu2+ into CN in the presence of hyperbranched polyethylene amine (HPEI) as a capping agent. The addition of Cu to CN (CNHPEI+Cu) increased the photocatalytic degradation efficiency of wastewater dye pollutant methylene blue (MB) from 42 % to 95 %. E. coli and MS2 performed best in terms of inactivation to CNHPEI+Cu, achieving 5.5 ± 0.3 and 5.3 ± 0.1 log inactivation after 60 min of exposure, respectively. Excellent catalyst reusability and photocatalytic activity for MB in various types were obtained. To investigate the photocatalyst structure, morphology, optical, and photoelectric properties, we used X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and photocatalytic activity. It was found through XRD and XPS that the prepared photocatalysts were made up of Cu-doped CN and that the valence state of Cu was Cu0. Under the visible part of the solar spectrum (>400 nm), the N2 adsorption-desorption isotherms of pure CN, CNHPEI, and CNHPEI+Cu showed that copper did not alter the microstructure of pure CN. The photocatalytic activity of CNHPEI+Cu was improved by incorporating Cu0 into CN, as this reduces the rate of electron-hole recombination in pure CN and accelerates the separation of electron-hole pairs. Electron spin resonance (ESR) spin trap experiments on the production of reactive oxygen species (ROS) from CNHPEI+Cu under visible light indicate that the presence of superoxide radicals (O2•−), hydroxyl radicals (•OH) and holes could enhance the photocatalytic activity of the material.

Pretreatment strategies of precursors for efficient photocatalytic hydrogen production of graphitic phase carbon nitride

The most sustainable preparation method for nanostructured materials must be urgently determined. In particular, the influence of different precursor pretreatment strategies on the structure and photocatalytic performance of highly attractive Graphitic carbon nitride photocatalyst is necessary to determine the most effective precursor pretreatment strategy. In this paper, three different precursor pretreatment methods were used to prepare g-C3N4 materials, so namely direct mixing (CN-C), freeze-drying, hydrothermal (CN-H) with thermal condensation polymerization two-step method processed urea, melamine and NH4Cl precursor mixtures. The results showed that NH4Cl, as a template, would not destroy the integrity of the tristriazine structural units in the product, and the CN-H sample had a lamellar structure, and the specific surface area and pore volume of the sample increased, which could provide more active reaction sites for photocatalytic H2 production, had the highest and most stable H2 evolution rate, up to 118.4 μmol g−1, about 1.7 times CN-C’s. This strategy provides a new idea for the design of g-C3N4 photocatalyst.

A novel method to synthesis of oxygen doped graphitic carbon nitride with outstanding photocatalytic efficiency for the degradation organic pollutants

Contamination of water sources with organic pollutants seriously threatens the environment and living organisms, so it is necessary to remove them from these sources with a proper method. Photocatalytic degradation of such pollutants can be an effective, low-cost and eco-friendly method. In this study, a new method, porous oxygen-doped Graphitic carbon nitride (POCN) photocatalyst was synthesized by pre-exfoliation of bulk graphitic carbon nitride in hydrogen peroxide followed by calcination of the resulting exfoliated and oxygenated sample at 550 °C. In fact, in this method, a combination of three strategies, nanostructure preparation, band gap engineering and defect introduction into the g-C3N4 were used to improve the efficiency of photocatalyst. The synthesized sample was characterized using XRD, FESEM, TEM, FTIR, DRS, PL, EDX, XPS, and BET-EJH. The efficiency of the prepared photocatalyst was evaluated with its ability to degrade Congo Red (CR) in aqueous solution under visible light using two light sources, LED lamp and daylight. POCN removed the CR in a short time. The degradation rate was higher under sunlight. The free radical trapping tests showed that superoxide radical anions (O2−) are the active species and are mainly responsible for color degradation.

Long-Term Characterization of Oxidation Processes in Graphitic Carbon Nitride Photocatalyst Materials via Electron Paramagnetic Resonance Spectroscopy.

Graphitic carbon nitride (gCN) materials have been shown to efficiently perform light-induced water splitting, carbon dioxide reduction, and environmental remediation in a cost-effective way. However, gCN suffers from rapid charge-carrier recombination, inefficient light absorption, and poor long-term stability which greatly hinders photocatalytic performance. To determine the underlying catalytic mechanisms and overall contributions that will improve performance, the electronic structure of gCN materials has been investigated using electron paramagnetic resonance (EPR) spectroscopy. Through lineshape analysis and relaxation behavior, evidence of two independent spin species were determined to be present in catalytically active gCN materials. These two contributions to the total lineshape respond independently to light exposure such that the previously established catalytically active spin system remains responsive while the newly observed, superimposed EPR signal is not increased during exposure to light. The time dependence of these two peaks present in gCN EPR spectra recorded sequentially in air over several months demonstrates a steady change in the electronic structure of the gCN framework over time. This light-independent, slowly evolving additional spin center is demonstrated to be the result of oxidative processes occurring as a result of exposure to the environment and is confirmed by forced oxidation experiments. This oxidized gCN exhibits lower H2 production rates and indicates quenching of the overall gCN catalytic activity over longer reaction times. A general model for the newly generated spin centers is given and strategies for the alleviation of oxidative products within the gCN framework are discussed in the context of improving photocatalytic activity over extended durations as required for future functional photocatalytic device development.

Revolutionizing photocatalytic water treatment: An in-depth exploration of g-C3N4 iron oxide and carbon-mediated upgrading for an optimal decontamination of Vltava river water

Efficient water decontamination and bacterial eradication represent the core objectives of our study. Fresh water samples taken from the Vltava River were used in all experiments. The goal was achieved by synthesis of graphitic carbon nitride (g-C3N4) photocatalyst modified with a combination of carbon (C) and iron oxide (Fe3O4). Carbon and iron oxide nanoparticles with different loadings were incorporated within the g-C3N4 nano-sheets by the wet impregnation method. Heat treatment was applied in order to achieve photocatalyst and nanomaterials cohesion. Photocatalysts and their precursors were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), ultraviolet-visible spectroscopy (UV–vis), photoluminescence, and Raman spectroscopy. The metal and non-metal sample composed of 1 C- 1Fe3O4/g-C3N4 revealed the best catalytic performance by eradicating bacterial species (N/N0 = 99.9%) under 30 min of light irradiation. The photocatalyst also showed a good activity in methylene blue (MB) degradation (C/C0 = 92%) under 180 min of visible light. The high activity of the treated photocatalyst 1 C- 1Fe3O4/g-C3N4 was attributed to an improvement in electrochemical properties and was also attributed to the double synergic mechanism due to the concurrent presence of iron and carbon nanoparticles in the g- C3N4 sheets. Moreover, the photocatalyst maintained a steady 99.9% bacterial degradation efficiency for 3 consecutive runs, proving its reusability. This exceptional catalytic activity, coupled with its stability and non-toxic nature shows the transformative potential of our material in revolutionizing water purification technologies. Our research underscores a significant progress towards addressing contaminants and energy challenges, and holds promise for a new era of sustainable water treatment.

Precursor-dependent fabrication of exfoliated graphitic carbon nitride (gCN) for enhanced photocatalytic and antimicrobial activity under visible light irradiation

In this work, we report the effective fabrication of exfoliated graphitic carbon nitride (gCN) photocatalysts through thermal exfoliation utilizing melamine, urea, and a combination of the two as precursors. As fabricated photocatalysts were characterized by different analytical techniques like XRD, FT-IR, UV-DRS, BET, FE-SEM HRTEM and XPS. Combining the various findings, it found that the gCN synthesized from urea has a loose nanosheet-like structure with smaller lamellae and a high surface area with porosity. The specific surface area for U-gCN was observed to be 168.98 m2 g−1, which was nearly 10 times higher than that of M-gCN (≈14.56 m2 g−1). Band gap energies using Tauc plot were estimated to be 2.57 eV for M-gCN, 2.68 eV for UM-gCN, and 2.82 eV for U-gCN, difference in the band gap energies was due to the peak shift observed in UV-DRS spectra. It was observed that thermally exfoliated U-gCN nanosheets were observed to be 5 times more efficient (98.4% degradation in 60 min) than M-gCN and UM-gCN in the photo-degradation of Methylene blue (MB) dye. Similarly, U-gCN photocatalyst showed remarkable ability to degrade tetracycline (TC) drug and the results exhibited that the TC antibiotic was almost completely degraded within 60 min of light exposure, at a rate of 0.0065 min−1. Scavenger studies were also carried out to investigate the reactive species. Further the plausible degradation mechanism was studied by combining the results of Tauc plot and VB-XPS. Additionally, photocatalytic antibacterial experiments revealed that U-gCN have remarkable antibacterial activity against S. aureus bacteria. Overall, enormous thin sheet-like arrangement, porous structure (which leads to effective charge separation), high surface area and extended light absorption characteristics are all contributing factors for the remarkable photocatalytic efficiency of U-gCN.

Photothermal-Assisted Photocatalytic Degradation of Tetracycline in Seawater Based on the Black g-C3N4 Nanosheets with Cyano Group Defects

As a broad-spectrum antibiotic, tetracycline (TC) has been continually detected in soil and seawater environments, which poses a great threat to the ecological environment and human health. Herein, a black graphitic carbon nitride (CN-B) photocatalyst was synthesized by the one-step calcination method of urea and phloxine B for the degradation of tetracycline TC in seawater under visible light irradiation. The experimental results showed that the photocatalytic degradation rate of optimal CN-B-0.1 for TC degradation was 92% at room temperature within 2 h, which was 1.3 times that of pure CN (69%). This excellent photocatalytic degradation performance stems from the following factors: (i) ultrathin nanosheet thickness reduces the charge transfer distance; (ii) the cyanogen defect promotes photogenerated carriers’ separation; (iii) and the photothermal effect of CN-B increases the reaction temperature and enhances the photocatalytic activity. This study provides new insight into the design of photocatalysts for the photothermal-assisted photocatalytic degradation of antibiotic pollutants.

Developing self-floating N-defective graphitic carbon nitride photocatalyst for efficient photodegradation of Microcystin-LR under visible light

The frequent occurrence of algal blooms in water bodies leads to a significant accumulation of microcystin-LR (MC-LR). In this study, we developed a porous foam-like self-floating N-deficient g-C3N4 (SFGN) photocatalyst for efficient photocatalytic degradation of MC-LR. Both the characterization results and DFT calculations indicate that the surface defects and floating state of SFGN synergistically enhance light harvesting and photogenerated carrier migration rate. The photocatalytic process achieved a nearly 100 % removal rate of MC-LR within 90 min, while the self-floating state of SFGN maintained good mechanical strength. ESR and radical capture experiments revealed that the primary active species responsible for the photocatalytic process was OH. This finding confirmed that the fragmentation of MC-LR occurs as a result of OH attacking the MC-LR ring. LC–MS analysis indicated that majority of the MC-LR molecules were mineralized into small molecules, allowing us to infer possible degradation pathways. Furthermore, after four consecutive cycles, SFGN exhibited remarkable reusability and stability, highlighting the potential of floating photocatalysis as a promising technique for MC-LR degradation.

Synthesis of solar-driven Cu-doped graphitic carbon nitride photocatalyst for enhanced removal of caffeine in wastewater

Caffeine (CaF), a widely consumed compound, has been associated with various harmful effects on human health, including metabolic, cardiovascular disease, and reproductive disorders. Moreover, it poses a signifincant threat to organisms and aquatic ecosystems, leading to water pollution concerns. Therefore, the removal of CaF from wastewater is crucial for mitigating water pollution and minimizing its detrimental impacts on both humans and the environment. In this study, a solar-driven Cu-doped graphitic carbon nitride (Cu/CN) photocatalyst was synthesized and evaluated for its effectiveness in oxidizing CaF in wastewater. The Cu/CN photocatalyst, with a low band gap energy of 2.58eV, exhibited superior performance in degrading CaF compared to pure graphitic carbon nitride (CN). Under solar light irradiation, CuCN achieved a remarkable CaF degradation efficiency of 98.7% CaF, surpassing CN's efficiency of 74.5% by 24.2%. The synthesized Cu/CN photocatalyst demonstrated excellent removal capability, achieving a removal rate of over 88% for CaF in wastewater. Moreover, the reusability test showed that Cu/CN could be successfully reused up to five cycles maintaining a high removal efficiency of 74% for CaF in the fifth cycle. Additionally, the study elucidated the oxidation mechanism of CaF using solar-driven Cu/CN photocatalyst and highlighted the environmental implications of the process.

Integrating K and P co-doped g-C3N4 with ZnFe2O4 and graphene oxide for S-scheme-based enhanced adsorption coupled photocatalytic real wastewater treatment

Recently, there has been a significant increase in the interest of using photocatalysis for environmental clean-up applications. In this research, potassium, and phosphorus co-doped graphitic carbon nitride (KPCN) photocatalyst modified with graphene oxide (GO) and heterostructured with ZnFe2O4 was synthesized via the hydrothermal method (KPCN/GO/ZnFe2O4). The photoactivity of KPCN/GO/ZnFe2O4 photocatalyst was examined for the photocatalytic degradation of target pollutants such as methylene blue (MB) dye, rhodamine B (RhB) dye, and tetracycline (TC) antibiotic. Furthermore, the chemical oxygen demand (COD) removal efficiency for real wastewater was determined to explore the practical application of KPCN/GO/ZnFe2O4 photocatalyst. The degradation efficiencies of bare graphitic carbon nitride, KPCN, KPCN/GO, and KPCN/GO/ZnFe2O4 photocatalysts for tetracycline antibiotics were 30%, 42%, 57%, and 87% within 60 min, respectively. Moreover, KPCN/GO/ZnFe2O4 photocatalyst showed 71% COD removal efficiency within 240 min. The •OH and •O2− were the major reactive species in the photocatalytic process. Results showed that the degradation efficiencies of graphitic carbon nitride were greatly enhanced upon doping and further improved with the addition of GO and ZnFe2O4. Doping improved light harvesting, GO enhanced the adsorption ability and heterojunction with ZnFe2O4 enhanced the charge separation as well as the reusability of synthesized KPCN/GO/ZnFe2O4 photocatalyst.

Activated g-C3N4 Photocatalyst with Defect Engineering for Efficient Reduction of CO2 in Water

The conversion and utilization of CO2 into hydrocarbon fuel using solar energy is an attractive way to reduce CO2 emissions. In the photocatalytic CO2 conversion process, a synergistic enhancement of both photoreaction and chemical reaction is quite important for promoting the conversion. Here, we present a facile method for preparing a defective and activated graphitic carbon nitride (g-C3N4) photocatalyst, which exhibits a superior CO2-to-CO production of 32.06 μmol g–1 without sacrificial agent or noble metal. This is about 9.1 times higher than that of the defect containing g-C3N4 (3.51 μmol g–1). The activated g-C3N4, in which the TiO2 species coexist, not only improved the CO production to 54.03 umol g–1 but also reduced CO2 into CH4 with 2.50 umol g–1 in 5 h. This is because the coexistence of TiO2 species in activated g-C3N4 promotes molecule and electron transfer, as observed through experimental characterization techniques. Therefore, this work provides a novel insight into the synthesis of multifunctional g-C3N4 for efficient photocatalytic CO2 reduction with H2O.

Preparation of carbon self-doped g-C3N4 for efficient degradation of bisphenol A under visible light irradiation

In this study, visible-light-driven carbon self-doped graphitic carbon nitride photocatalyst was fabricated by a facile method with urea and ammonium citrate, and used for photodegradation of bisphenol A (BPA) in the aqueous environment. The experiments indicated that the prepared photocatalyst (C0.02CN) showed high catalytic activity, and 96.0%, 93.2%, and 95.5% BPA could be photodegraded in 150min under pH 3, 6, and 11, respectively. The photocatalytic degradation rate (0.018min-1) and mineralization (27.6%) of C0.02CN for BPA were about 6.7 and 3.5 times higher than those of the g-C3N4 (0.0027min-1, 7.87%), respectively. C0.02CN had high reusability with a photodegradation efficiency of 84.5% for BPA after 3 cycles. Moreover, C0.02CN introduced additional carbon atoms, which generated C-O-C bonds in the g-C3N4 lattice. In contrast to g-C3N4, carbon doping enhanced the visible light absorption range of C0.02CN, reduced its band gap, and improved the separation efficiency of photogenerated electron-hole pairs. Radical quenching experiment and ESR results revealed that superoxide radicals (•O2-) and photogenerated holes (h+) acted as important parts in the high photodegradation activity under visible light irradiation. This work puts forward a one-pot strategy for the preparation of carbon self-doped g-C3N4, displacing the high-energy consuming and complicated preparation technology with promising industrial applications.

Eradication of Gram-negative bacteria by reusable carbon nitride-coated cotton under visible light

A metal-free graphitic carbon nitride (GCN-T) photocatalyst obtained through a microwave-assisted technique was immobilised on cotton fabrics by an exhaustion method. Coated-cotton with only 0.81 % (w/w) of GCN-T (CO/GCN-T) presented effective antimicrobial properties against pathogenic bacteria, P. aeruginosa and E. coli, eradicating the retained bacteria after 60 min of direct irradiation with visible light. The self-cleaning activity of CO/GCN-T samples was also proved for the degradation of Rhodamine B (RhB) stains after 60 min of irradiation with a cost-effective Light Emitting Diode (LED) (λmax = 417 nm). In addition, CO/GCN-T did not hinder the growth of commensal skin bacteria Staphylococcus spp. and presented non-cytotoxicity to skin cell lines, such as fibroblasts (L929) and keratinocytes (HaCaT), so it can be stated that these textiles are promising for applications in direct contact with the skin. Therefore, these are relevant findings since a textile substrate, with the ability to remove or eliminate harmful microorganisms, is an asset for the healthcare area.

Salt-Mediated Structural Transformation in Carbon Nitride: From Regulated Atomic Configurations to Enhanced Photocatalysis

Molten salts-assisted synthesis is widely used in the construction of high efficiency graphitic carbon nitride (g-C3N4) photocatalysts, and two isotypes of g-C3N4 have been synthesized by such method, namely poly (heptazine imide) (PHI) and poly (triazine imide) (PTI). However, the understanding of the structural changes taking place during the molten salt process and the structure–activity relationship of g-C3N4 polymorphs remain blurred. Herein, by regulating the treatment duration of g-C3N4 nanosheets (melon) in molten salts, we successfully synthesized g-C3N4 with phases of PHI, PHI/PTI and PTI. A continuous structural transformation induced by ions, in which melon transforms to a stable phase PTI via PHI, an intermediate state, was unveiled for the first time. In addition, results reveal that atomic configurations play a vital role in photo absorption, and charge carrier transfer and surface reaction, leading to significant differences in photocatalytic degradation. Among them, PHI with K+ and cyan groups modification, as well as high crystallinity, exhibits remarkable degradation efficiency, with 90% removal of tetracycline in 10 min and 80% removal of phenol in 60 min. This study sheds light on a deeper understanding for the molten salt-assisted synthesis and provides new ideas for preparing efficient organic semiconductor photocatalysts.

Fabrication of an intimately coupled photocatalysis and biofilm system for removing sulfamethoxazole from wastewater: Effectiveness, degradation pathway and microbial community analysis

Sulfamethoxazole (SMX) is an extensively applied antibiotic frequently detected in municipal wastewater, which cannot be efficiently removed by conventional biological wastewater processes. In this work, an intimately coupled photocatalysis and biodegradation (ICPB) system consisting of Fe3+-doped graphitic carbon nitride photocatalyst and biofilm carriers was fabricated to remove SMX. The results of wastewater treatment experiments showed that 81.2 ± 2.1% of SMX was removed in the ICPB system during the 12 h, while only 23.7 ± 4.0% was removed in the biofilm system within the same time. In the ICPB system, photocatalysis played a key role in removing SMX by producing hydroxyl radicals and superoxide radicals. Besides, the synergism between photocatalysis and biodegradation enhanced the mineralization of SMX. To understand the degradation process of SMX, nine degradation products and possible degradation pathways of SMX were analyzed. The results of high throughput sequencing showed that the diversity, abundance, and structure of the biofilm microbial community remained stable in the ICPB system at the end of the experiments, which suggested that microorganisms had accommodated to the environment of the ICPB system. This study could provide insights into the application of the ICPB system in treating antibiotic-contaminated wastewater.

Insight into the effect of Li/P co-doping on the electronic structure and photocatalytic performance of g-C3N4 by the first principle

In recent years element doping has been considered an essential method for developing low-cost and highly efficient graphitic carbon nitride (g-C3N4) photocatalysts for environmental remediation. In this work, we have synthesized Li and P co-doped g-C3N4 nanosheet (Li/P-g-C3N4) by a facile calcination process for the methylene blue (MB) dye degradation. With increased visible light (VL) absorption, improved electron-hole (e-/h+) pair separation, and larger surface area, the dye degradation rate constant (k) for Li/P-g-C3N4 is approximately 2.6 times faster than g-C3N4 under visible light. The density functional theory (DFT) calculation has also confirmed that Li and P co-doping into the g-C3N4 narrowed the bandgap, increased the photogenerated e-/h+ delocalization, and increased the charge transfer (CT) rate. Hence, the combined effect of metal and non-metal co-doping is the reason behind the outstanding photocatalytic efficiency of the Li/P-g-C3N4. The current study expands the performance window for metal/non-metal co-doped g-C3N4 while maintaining excellent quality.