Doped Graphitic Carbon Nitride Research Articles

Rosuvastatin calcium electrochemical sensor based on a sulfur doped graphitic carbon nitride modified glassy carbon electrode: A metal free analysis approach

This study explored the benefits of heteroatom doping to enhance sensor efficiency by developing a low-cost, metal-free electrochemical sensor. Melamine and sulfur powders were used as precursors in a one-step thermal polymerization technique to produce sulfur-doped graphitic carbon nitride (S-g-C3N4). The structural and morphological properties of the synthesized materials were extensively analyzed using several techniques, including XRD, XPS, SEM, HRTEM, and EIS. The results show a significant decrease in impedance, indicating improved conductivity. In addition, the doping approach significantly enhanced the reduction in current receptivity compared to unmodified graphitic carbon nitride (g-C3N4). We used differential pulse voltammetry (DPV) and cyclic voltammetry (CV) to instigate the electro-oxidation of Rosuvastatin calcium (ROS), as well as concentration-dependence and selectivity studies, using a sulfur-doped graphitic carbon nitride-modified glassy carbon electrode (S-g-C3N4@GCE). S-g-C3N4@GCE exhibited outstanding performance with an extremely low detection limit of 0.10 µM and a wide linear range (5–100 µM), highlighting its potential for highly sensitive assays and its exceptional capability to operate over a broad ROS concentration range.

Photoluminescence Quenching in Metal Doped Graphitic Carbon Nitride: Possibilities Toward Metal Sensors

AbstractThe present work describes the synthesis of graphitic carbon nitride (GCN) via simple two‐step thermal decomposition of urea at a moderate temperature of 550 °C. The as‐synthesized GCN is further doped with transition metals like nickel, and both the pure and doped GCN are characterized by X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM), X‐ray photoelectron spectroscopy (XPS), and Fourier transformed infrared (FTIR) spectroscopy. XRD shows the perfect phase formation in the pure GCN, which also remains in the doped sample but with much lesser crystallinity. FESEM shows that after doping, the small chips‐like structure of GCN gets transformed to an elongated one. XPS confirms the successful doping by keeping the signature of both nickel 2P1/2 and 2P3/2 oxidation states in the spectra, whereas FTIR gave an idea about different bonding present in the sample. The pure sample, when irradiated with an excitation wavelength of 350 nm, gives an intense peak at 457 nm, which gets considerably quenched in the case of the doped sample. However, a new peak appears in the photoluminescence (PL) spectra of the doped sample at 624 nm. The quenching of PL intensity in the doped sample is assumed to be due to the fact that the dopant‐induced state traps the electron, hindering them from immediate recombination. This quenching of PL intensity generates the possibilities of sensing the presence of different metals and thus taking measurable steps for removing them. The CIE chromaticity diagrams for the doped and undoped samples confirm that the emission color changes from blue to cyan region after the doping.

Characterisation Analysis of Sulphur and Phosphorous Doped and Co-doped Graphitic Carbon Nitride (g-C3N4) Materials

Graphitic carbon nitride (g-C3N4) is tailored with doping of different non-metals (Sulphur and Phosphorus). For synthesis through thermal condensation method, the mixtures of urea and dopant with diverse concentrations have been added for preparation of materials. The basic effect of doping and its concentration on the structural morphology and absorption spectra of the samples is investigated in detail. Pure g-C3N4 suffers from high recombination rate of photogenerated electron-hole pairs resulting in low photocatalytic activity. Different techniques like X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, and Photoluminescence spectroscopy (PL) have been used for the characterization. X-ray diffraction studies confirm the formation of the g-C3N4 structure and SEM images reveal crumpled sheets and irregular plate like shapes of the doped graphitic nitride samples. FTIR analysis identify the presence of surface amino (N-H) and water (O-H) groups, cyano terminal group (C≡N), (C≡C), C–N) and (C=N) bonds and breathing mode of the tri-s-triazine units in the samples. PL spectra shows that the sulphur and phosphorus co-doped PSGCN (8 wt.%) sample is better for photocatalytic activity.

In-situ ‘X’ doped ‘GCN’ photocatalyst enables selective aldehyde synthesis via photo-oxidation of benzyl alcohol under ambient conditions

Photo-oxidative selective conversion of benzyl alcohols using graphitic carbon nitride (GCN) is a sustainable strategy for conventional metal-doped heterogeneous catalytic oxidation systems. Non-metal doped graphitic carbon nitride (a subclass of GCN) enhances its properties as an efficient photocatalyst for oxidation. These heteroatom non-metal dopants alter the optical energy gap and chemical and electronic properties of GCN, making it ideal for creating cost-effective, practical utility. So, herein, we designed heteroatoms (X = B, S, C) doped GCN photocatalysts derived from melamine (M) with different heteroatom ingredients and compared their activity in detail. Among these, the photo-oxidation of benzyl alcohol under blue LED by S-doped GCN (S-GCN) photocatalyst exhibits utmost higher photocatalytic activity than other heteroatoms doped GCN photocatalyst due to suitable band gap and slow photoinduced charge carriers recombination. The suitable energy gap with higher chemical stability is accountable for the substantial increase in the photocatalytic efficiency of S-GCN in the solar light responsive integrating reactions of oxidation of benzyl alcohol in aerobic conditions. Attaining an exceptional >99 % selectivity towards benzaldehyde (up to 5 cycles without significant loss of activity) marks a remarkable milestone. This opens up new possibilities for using these simple non-metal-doped photocatalysts in fine chemical synthesis.

K+ doped graphitic carbon nitride modified layered double oxide nanocomposite towards high-efficiency CO2 adsorption at intermediate temperature

As a novel medium-temperature CO2 adsorbent, K+ doped and graphitic carbon nitride modified layered double oxide composite (xK/CN-LDO, x = 15, 20, and 25 wt%) were prepared via in-situ synthesis and impregnation methods. Their adsorption performance was evaluated by thermal gravimetric analyzer. g-C3N4-modified LDO (CN-LDO) exhibited a CO2 adsorption capacity of 0.46 mmol/g, 1.39 times higher than the 0.33 mmol/g observed for LDO. This enhancement was attributed to the increased specific surface area and the exposure of additional extractable sites. Further doping with K significantly enhanced the adsorption uptake of xK/CN-LDO. Notably, 20 K/CN-LDO achieved the highest CO2 adsorption uptake of 0.82 mmol/g, representing a 2.48-fold increase compared to LDO. This further enhancement can be ascribed to K's ability to alter the distribution of chemical adsorption sites, thereby providing an optimal number of basic sites. In-situ DRIFTS analysis revealed that CO2 predominantly existed in the form of carbonate species, while adsorption kinetics studies show that the dominant mechanism is chemical adsorption, with external diffusion being the primary adsorption process. Furthermore, 20 K/CN-LDO exhibited significantly higher regeneration efficiency of 72.4 % after 10 cycles, showcasing its promising practical prospects for application in the SEWGS process.

Synergistic combination of Mn/Fe bimetal-doped carbon nitride and peroxymonosulfate for efficient photocatalytic degradation of antibiotics

The widespread of antibiotics has resulted in potential threats to the aquatic environment and human health. The visible light-assisted peroxymonosulfate (PMS) activation method is considered to be an effective way to remove antibiotics in wastewater. In this study, Mn/Fe bimetal doped graphitic carbon nitride (MnFe-CN-x) was first synthesized for PMS activation under visible light towards tetracycline (TC) removal. The optimized MnFe-CN-50 possessed the excellent photocatalytic activity, PMS activation performance and photo-Fenton-like synergistic effect. In the photo-Fenton-like system, TC (20 mg L−1) was degraded by 99 % in 50 min and the kinetic constant was 0.074 min−1. The high dispersion of Mn and Fe in carbon nitride inhibited the recombination of charge carriers in MnFe-CN-x, increased its photocurrent density and charge mobility, effectively optimized the electronic structure, and promoted the generation of 1O2. Based on the analytical results of predictive toxicity evaluation software (TEST), it was confirmed that MnFe-CN-x could effectively reduce the environmental risks associated with antibiotic contamination. This study provided new insights into synthesizing bimetal-doped graphitic carbon nitride and the use of synergistic effects of photocatalysis and PMS activation to remove organic pollutants from wastewater.

Electrodeposited Phosphorous-Doped Graphitic Carbon Nitride as A Versatile Metal Free Interface for Tryptophan Detection in Dietary, Nutritional, and Clinical Samples

Tryptophan (TRP) is an essential amino acid that is crucial for human growth and must be obtained through a dietary source or nutritional supplements. Both, the overconsumption or deficiency induces clinical symptoms. Therefore, a sensitive and selective method for quantifying TRP in dietary products, nutritional supplements, and clinical samples is essential. In this work, we have electrodeposited phosphorous doped graphitic carbon nitride (P-gCN) for developing a TRP voltammetric sensor. Outlining the benefits of electrodeposition over drop-casting, the developed P-gCN | GCE sensor demonstrated 7.83 times more sensitivity and a negative shift of ∼0.10 V for TRP electro-oxidation compared to unmodified electrode implying its remarkable electrocatalytic activity. The sensor featured a detection-limit of 7.1 nM and showcased excellent stability, repeatability and reproducibility. The practical utility of the sensor was manifested by estimating TRP in over 12 real samples including, food products, nutritional supplements and clinical samples (urine and human blood serum).

Platinum decorated phosphorous doped graphitic carbon nitride supported molecularly imprinted carbon fibre electrode as a nano-interface for the detection of butylated hydroxy anisole

This research generated an electrochemical sensor using a carbon fibre (CFP) paper electrode coated using platinum-decorated phosphorous doped graphitic carbon nitride (Pt/PgCN). This sensor was designed to detect butylated hydroxy anisole (BHA) selectively and sensitively. The molecularly imprinted polymers (MIPs) were synthesized onto the Pt/PgCN coated CFP surface through electropolymerization using BHA as a template and 3-thiophene acetic acid as monomer. Numerous analytical methods were used to characterise the sensor electrode, including cyclic voltammetry, impedance spectroscopy, and electron microscopy. The results showed that the synergetic effect of PgCN, Pt nanoparticles, and PTAA, PgCN and Pt had a positive impact on the electrochemical detection, the sensor's linear range was determined to be between 5 × 10−10 M and 2.1 × 10−7 M. The sensor demonstrated excellent stability, good reproducibility, and high selectivity for detecting BHA. Moreover, the proposed sensor successfully detected BHA in real samples.

Phyto-synthesis of tin oxide nanoparticles using Diospyros mollis leaves extract doped graphitic carbon nitride for photocatalytic methylene blue degradation and hydrogen peroxide production

In this study, tin oxide nanoparticles (SnO2 NPs) were combined with graphitic carbon nitride (gCN) to produce the SnO2/gCN composite for photocatalytic methylene blue (MB) degradation and H2O2 production. Specifically, SnO2 NPs were initially prepared using a biological pathway from Diospyros mollis leaves extract, followed by the incorporation on gCN via calcination treatment. Characterization of SnO2/gCN was conducted through analytical methods, including scanning electron microscopy, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N2 sorption isotherm, photoluminescence spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS). The optical band gap of the nanocomposite was also evaluated to be 2.44 eV using the Tauc plot and UV-DRS, which is lower than pristine gCN. The photocatalytic performance over the optimal 1.0SnO2/gCN sample was resultingly investigated, reaching over 99.76 % of MB degradation efficiency within 120 min, and 4060.78 μM/g.h of H2O2 production rate under visible light radiation. Insights into the mechanism revealed the vital participation of reactive radicals, especially •O2− and •OH, in the degradation of MB molecules, while the reusability of 1.0SnO2/gCN was also maintained after 4 succeeding photocatalytic cycles. Such findings affirm the promising applicability of the constructed SnO2/gCN material in many industries, namely the environmental remediation and cleaner production sectors.

Zn(II)-MOFs nanosheets interaction with P-doped graphitic carbon nitride nanosheets for effective overall water splitting in alkaline medium

We developed an electrocatalyst made up of two dimensional nanosheets interacted with another two-dimensional nanosheets (2D-2D) to explore the mediation of overall water splitting in alkaline medium. The 2D-2D electrocatalyst is denoted as ZIF-P-GCN nanosheets derived from metal organic frameworks (MOFs) such as zinc coordinated imidazole framework (ZIF-8) nanosheets interacted with optimized phosphorous doped graphitic carbon nitride (P-GCN) nanosheets. The developed electrocatalyst exhibits high efficiency for oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water splitting. Initially, the electrocatalyst was studied using FT-IR spectra, XRD patterns, XPS analysis, BET surface area studies, FE-SEM and HR-TEM analyses to understand its structural and morphological properties. Moreover, the synthesized ZIF-P-GCN nanosheets are porous in nature, thereby subsequently, its electrocatalytic activity has been investigated. Compared to ZIF-8 or P-GCN nanosheets, the prepared 2D-2D interacted ZIF-P-GCN nanosheets loaded on the GCE electrode showed excellent and stable electrocatalytic performance with a low overpotential of 290 and 200 mV for OER and HER, respectively, to reach the current density of 10 mA cm−2 in alkaline medium. Besides, low Tafel slope values are observed such as 30.26 mV Dec-1 for OER and 46.53 mV Dec-1 for HER, respectively, in 3 M KOH. Furthermore, a complete electrochemical cell was constructed using ZIF-P-GCN//ZIF-P-GCN nanosheets loaded Ni foam electrodes for overall water splitting to achieve a minimum cell voltage of 1.61 V at a current density of 10 mA cm−2, which is comparable to standard Pt/C//RuO2 cell system. Thus, the work attempts to develop an effective and stable 2D-2D interacted bifunctional electrocatalyst for overall water splitting using a novel and easy route.

Nanoengineered phosphorus doped graphitic carbon nitride based ultrasensitive biosensing platform for Swine flu detection.

In the present study, we developed an amino-polyindole modified phosphorus doped graphitic carbon nitride nanomaterial (APIN/P-g-C3N4) based immunosensing biochip for Serum amyloid A (SAA) biomarker towards early diagnosis of Swine flu. The P-g-C3N4 was synthesis via polycondensation and functionalized with APIN. Further, the biochip was fabricated by modifying the working area of SPE with APIN/P-g-C3N4 using drop cast method, APIN introduced the larger loading of -NH2 group moieties onto P-g-C3N4 matrix and benefitted to reinforced the biomolecules via covalent linkages. The monoclonal anti-SAA was conjugated onto APIN/P-g-C3N4/SPE using EDC-NHS chemistry and BSA was added for non-specific site blocking. The structural, chemical, composition and morphological characteristics of the synthesized, functionalized nanomaterial and fabricated biochips were investigated by XRD, XPS, FT-IR spectroscopy, SEM, FE-SEM and TEM techniques. Further, the electrochemical characterization and response studies of fabricated biochip were analyzed using the CV and DPV techniques. Based on the analytical performance of the proposed immunosensing biochip i.e. BSA/anti-SAA/APIN/P-g-C3N4/SPE, it is capable to detect SAA protein with ultra sensitivity of 79.5 μA log (mL ng-1) cm-2, ultralow limit of detection of 5ngmL-1 and wider linear detection range of 5ngmL-1-500μgmL-1 with quick response time of 10min. Moreover, the fabricated immunosensing biochips was used to analyse SAA protein in spiked serum samples and the achieved results demonstrated the good agreement with the electrochemical response observed in standard SAA protein samples in analytical solution. The proposed biochip can provide insights for developing a wide range of clinical screening tools for detecting various contagious diseases.

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.

Tuning CH4 Productivity from Visible Light‐Driven Gas‐Phase CO2 Photocatalytic Reduction on Doped g‐C3N4/TiO2 Heterojunctions

Herein, visible light‐driven gas‐phase photocatalytic CO2 reduction into CH4 is tuned by designing optimized three‐component Au/doped C3N4/TiO2 composite photocatalysts. The key point strategy consists in the formation of high‐quality C3N4/TiO2 heterojunction by associating low containing doped graphitic carbon nitride to commercially available TiO2 UV‐100. Those heterojunctions result in both visible light sensitization and increased charge‐carrier separation. Further deposition of small Au nanoparticles (≈3 nm), quite exclusively onto TiO2 surfaces, mainly acts as electron trapping/cocatalytic functions without excluding surface plasmonic effects. The resulting doped g‐C3N4 material exhibits enhanced visible light harvesting properties, especially in the case of C‐doping. In addition, it is assumed that B– and C–C3N4 doping, leading to a more or less lower conduction band position, is the impacting factor toward total CH4 selectivity achievement. The (0.77 wt%)Au/(0.59 wt%)C–C3N4/TiO2 composite photocatalyst, exhibiting the best compromise between the various impacting factors, leads to a continuous productivity rate of CH4 of 8.5 μmol h−1 g−1 under visible light irradiation over at least 10 h. To the best of knowledge, this level of performance is unprecedented under continuous gas‐phase flowing CO2 in the presence of water as reducing agent, without addition of any sacrificial agent.

Ultrasound-Augmented Multienzyme-like Nanozyme Hydrogel Spray for Promoting Diabetic Wound Healing.

Treatment of diabetic foot ulcers (DFU) needs to reduce inflammation, relieve hypoxia, lower blood glucose, promote angiogenesis, and eliminate pathogenic bacteria, but the therapeutic efficacy is greatly limited by the diversity and synergy of drug functions as well as the DFU microenvironment itself. Herein, an ultrasound-augmented multienzyme-like nanozyme hydrogel spray was developed using hyaluronic acid encapsulated l-arginine and ultrasmall gold nanoparticles and Cu1.6O nanoparticles coloaded phosphorus doped graphitic carbon nitride nanosheets (ACPCAH). This nanozyme hydrogel spray possesses five types of enzyme-like activities, including superoxide dismutase (SOD)-, catalase (CAT)-, glucose oxidase (GOx)-, peroxidase (POD)-, and nitric oxide synthase (NOS)-like activities. The kinetics and reaction mechanism of the sonodynamic/sonothermal synergistic enhancement of the SOD-CAT-GOx-POD/NOS cascade reaction of ACPCAH are fully investigated. Both in vitro and in vivo tests demonstrate that this nanozyme hydrogel spray can be activated by the DFU microenvironment to reduce inflammation, relieve hypoxia, lower blood glucose, promote angiogenesis, and eliminate pathogenic bacteria, thus accelerating diabetic wound healing effectively. This study highlights a competitive approach based on multienzyme-like nanozymes for the development of all-in-one DFU therapies.

Synergetic effects of Mo2C sphere/SCN nanocatalysts interface for nanomolar detection of uric acid and folic acid in presence of interferences

Till to date, the application of sulfur-doped graphitic carbon nitride supported transition metal carbide interface for electrochemical sensor fabrication was less explored. In this work, we designed a simple synthesis of molybdenum carbide sphere embedded sulfur doped graphitic carbon nitride (Mo2C/SCN) catalyst for the nanomolar electrochemical sensor application. The synthesized Mo2C/SCN nanocatalyst was systematically characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with elemental mapping. The SEM images show that the porous SCN network adhered uniformly on Mo2C, causing a loss of crystallinity in the diffractogram. The corresponding elemental mapping of Mo2C/SCN shows distinct peaks for carbon (41.47%), nitrogen (32.54%), sulfur (1.37%), and molybdenum (24.62%) with no additional impurity peaks, reflecting the successful synthesis. Later, the glassy carbon electrode (GCE) was modified by Mo2C/SCN nanocatalyst for simultaneous sensing of uric acid (UA) and folic acid (FA). The fabricated Mo2C/SCN/GCE is capable of simultaneous and interference free electrochemical detection of UA and FA in a binary mixture. The limit of detection (LOD) calculated at Mo2C/SCN/GCE for UA and FA was 21.5 nM (0.09 – 47.0 μM) and 14.7 nM (0.09 – 167.25 μM) respectively by differential pulse voltammetric (DPV) technique. The presence of interferons has no significant effect on the sensor’s performance, making it suitable for real sample analysis. The present method can be extended to fabricate an electrochemical sensor for various molecules.

Construction of S-N-C bond for boosting bacteria-killing by synergistic effect of photocatalysis and nanozyme

Bacterial infection-related diseases are major public safety issues leads to millions of deaths annually. Herein, a porous sulfur doped graphitic carbon nitride (g-SCN) for ecofriendly, metal-free and low systemic toxicity were synthesized. Sulfur doping enables to broaden the absorption spectrum and promote the photocarriers separation for photocatalysis enhancement. Moreover, sulfur element will coordinate with nitrogen, changing the electronic state and endowing g-SCN with the property of nanozyme. More importantly, we established different models and confirmed that S-N-C coordination is the source of peroxidase (POD)-like activity through theory and experiment. The increased specific surface area of g-SCN, ascribing to the porous structure, makes it easier to trap bacteria. With the synergistic effect of photocatalysis and nanozyme, the prepared g-SCN has the ability to kill both gram-negative and gram-positive bacterium, with an antibacterial efficiency up to 100%. This work provides innovative synergistic strategy for constructing nanomaterials for highly efficient antibacterial therapy.

Toxic environmental drug nimesulide detection and degradation using the Bi-functional vanadium and phosphorous doped graphitic carbon nitride nanosheets

In this manuscript “Feed two birds with one seed” strategy was followed to study the electrochemical ability and photocatalytic Degradation of pharmaceutical effluent nimesulide (NIM) drugs. Heterogeneous solid-direct Z-scheme catalysts experienced many efforts in generating new materials to tackle environmental issues by exhibiting appropriate catalysts. Currently, graphitic carbon nitride (gCN) with its unique characteristics has attracted tremendous kindness among researchers due to its excellent potential for utilization as a bi-functional catalyst. In this research, the part of surface morphological engineering and band gap evolution in heterojunction solid-direct Z-scheme formation of vanadium and phosphorous doped gCN (V/P-gCN (VP)) will be considered. The proposed material is prepared by thermal decomposition and the analytical analysis was utilized to study the physio-chemical characteristics. These newly developed strategies are more useful to enhance the electrocatalytic and photocatalytic activity of gCN. In addition, specific information on the application of gCN-based catalysts in the bi-functional simultaneous process will be obtained in different reactions. The analytical parameters of the proposed sensor were adequate, with higher recovery values, and the detection limits and quantification range are 0.2 – 80 μM and 3 nM, respectively for the detection of NIM. Photocatalytic Degradation of NIM targets harmful pollutants obtained 98% within a short treatment time under visible light illumination. In addition, the possible degradation pathways of NIM drugs were studied using GC-MS analysis, which exhibited the degradation of NIM molecules with small fragments. These dual-functional approaches could provide sustainable and efficient strategies for both electro and photocatalyst to rectify environmental issues.

Oxygen doping facilitated N-vacancies in g-C3N4 regulates electronic band gap structure for trimethoprim and Cr (VI) mitigation: Simulation studies and photocatalytic degradation pathways

The strategic designing of graphitic carbon nitride (CN)by elemental doping is likely to generate nitrogen vacancies which benefit by serving as electron trapping sites or by introducing additional energy levels (mid-gap states). In this work, uracil-assisted oxygen doped graphitic carbon nitride (OCNv-Ux) was synthesized by the hydrothermal method. The OCNv-U40 exhibited vigorous photocatalytic efficiency for 98% trimethoprim (TMP) antibiotic degradation and 90.8% Cr (VI) reduction under visible light irradiations. A combined inference from experimental results and simulation studies indicates band gap reduction from 2.7 to 2.34 eV for extended visible light absorption up to 620 nm. In particular, the density of states comprehends band structure regulation by the electron redistribution resulting in valence band up shifting and downshift of the conduction band, as validated by Mott-Schottky spectra. The synergistic outcomes of nitrogen vacancies and oxygen doping sites restrain the recombination of electron-hole pairs by mid-gap state formation and also promote high oxygen molecule adsorption on the nitrogen vacancies. The pioneering advantage of highly adsorbed oxygen molecule leads to the generation of plentiful superoxide anion radicals along with indirect production of hydroxyl radicals via in-situ produced H2O2, evident by radical scavenging and electron paramagnetic resonance experiments. The effect of chloride and nitrate anions showed inhibitory effect on the TMP degradation efficiency. The identification of formed intermediates and TMP degradation mechanism involving oxidation, hydroxylation, and cleavage was proposed, as investigated by TMP DFT studies. This research accomplishes significant enhancement in pristine CN photocatalytic activity by the virtue of increased specific surface area, fully exposed N-vacancies active sites, optimized electronic, structure and visible light active band gap.

Organosilica-assisted superhydrophilic oxygen doped graphitic carbon nitride for improved photocatalytic H2 evolution

The regulation of surface wettability and heteroelement doping have been proved to be effective strategies to enhance photocatalytic H2 evolution activity of graphitic carbon nitride (CN) based photocatalysts. Herein, we report, for the first time, an organosilica assisted method was adopted to synthesize the superhydrophilic oxygen doped graphitic carbon nitride (O–CN). The presence of organosilica induced simultaneous oxygen-containing groups grafting and oxygen doping within carbon nitride substrate. The grafted oxygen-containing groups improved the surface hydrophilicity and water adsorption. Oxygen doping tailored electronic structure and localized electron distribution, contributing to extended visible light harvesting and elevated photoelectric conversion efficiency. As a result, the H2 generation rate of O–CN photocatalyst was 5.4 times higher than that of pristine CN photocatalyst attributed to the formation of hydrophilic groups and the oxygen doping.

Synthesis of Highly Active Doped Graphitic Carbon Nitride using Acid‐Functionalized Precursors for Efficient Adsorption and Photodegradation of Endocrine‐Disrupting Compounds

AbstractA highly active non‐metallic doped bulk graphitic carbon nitride (g‐C3N4) was synthesized via acid‐functionalized melamine decomposition. Specifically, melamine was treated with acetic acid, sulfuric acid, and phosphoric acid to obtain oxygen, sulfur, and phosphorus‐doped g‐C3N4 derivatives. Sulfur‐doped g‐C3N4 exhibited remarkable photocatalytic activity to degrade two environmentally harmful hormones, 17β‐estradiol, and 17α‐ethinylestradiol, due to its narrow energy bandgap and high surface area. The hormones were removed entirely in 30–45 min by adsorption in the dark, followed by photodegradation under visible light (430 nm). Furthermore, the pseudo‐second‐order kinetic model fitted the adsorption kinetics well, and photocatalytic degradation followed the exponential decay model. LC–MS identified the intermediate products for the photodegradation of 17β‐estradiol (E2). This study provides a simple one‐step method to synthesize highly reactive metal‐free doped bulk g‐C3N4 photocatalysts to remove harmful water pollutants.