Doped Graphitic Carbon Nitride Research Articles

2D Nanomaterial—Based Electrocatalyst for Water Soluble Hydroperoxide Reduction

Hydroperoxides generated on lipid peroxidation are highly reactive compounds, tend to form free radicals, and their elevated levels indicate the deterioration of lipid samples. A good alternative to the classical methods for hydroperoxide monitoring are the electroanalytical methods (e.g., a catalytic electrode for their redox-transformation). For this purpose, a series of metal oxides—doped graphitic carbon nitride 2D nanomaterials—have been examined under mild conditions (pH = 7, room temperature) as catalysts for the electrochemical reduction of two water-soluble hydroperoxides: hydrogen peroxide and tert-butyl hydroperoxide. Composition of the electrode modifying phase has been optimized with respect to the catalyst load and binding polymer concentration. The resulting catalytic electrode has been characterized by impedance studies, cyclic voltammetry and chronoamperometry. Electrocatalytic effect of the Co-g-C3N4/Nafion modified electrode on the electrochemical reduction of both hydroperoxides has been proved by comparative studies. An optimal range of operating potentials from −0.215 V to −0.415 V (vs. RHE) was selected with the highest sensitivity achieved at −0.415 V (vs. RHE). At this operating potential, a linear dynamic range from 0.4 to 14 mM has been established by means of constant-potential chronoamperometry with a sensitivity, which is two orders of magnitude higher than that obtained with polymer-covered electrode.

Non-oxidative Propane Dehydrogenation over Vanadium Doped Graphitic Carbon Nitride Catalysts

Non-oxidative Propane Dehydrogenation over Vanadium Doped Graphitic Carbon Nitride Catalysts

Observation of room temperature metal free ferromagnetism in sulfur doped graphitic carbon nitride

Generation of superior magnetic property in two-dimensional nanosheets is an important issue in condensed matter physics due to its potential exploitation in the field of Spintronic application. Metal-free ferromagnetism in 2D materials could generate a long spin lifetime due to its s/p electron configuration, which is the key factor for spin transfer. In the present work, we have synthesised 2D graphitic carbon nitride doped with sulfur (S) atom to investigate the magnetic property due to the interaction of the S atom with the lattice of graphitic carbon nitride. Due to S doping, we get a long-range ferromagnetic ordering in our sample, persisting upto room temperature, and the precise control of S concentration can tune the magnetic property of the system. Interestingly, the magnetotransport (MR) study shows a transition from positive MR at low temperature to negative MR at room temperature. The wave function shrinkage model explains the low-temperature positive MR, where the negative MR follows the weak localization effect. Thus, the overall magnetic and electrical response of S doped graphitic carbon nitride makes it a potential candidate for future spintronic application.

Cu doped graphitic C3N4 for p-nitrophenol reduction and sensing applications

A series of Cu doped graphitic carbon nitride (g-C3N4) catalysts with different ratios of copper were synthesized by thermal method, using urea and copper sulphate as precursors. XPS (X-ray Photoelectron Spectroscopy) studies indicated that the peak of N1s at 398.9 eV is due to CuN bond and a peak at 932.9 eV showed the presence of CuNC bond. Catalytic hydrogenation of p-nitrophenol (Para-NP) to para-aminophenol (Para-AP) in presence of g-C3N4 (gCN) and copper doped g-C3N4 (CN-Cu) with sodium borohydride (NaBH4) was investigated by UV–Visible spectroscopy. The as-synthesized graphitic carbon nitride with 1% copper (CN-1Cu) doped sample exhibits superior catalytic performance and higher stability compared to fine Cu powder in the second cycle. Additionally, electrochemical paracetamol sensing properties of the samples were studied using cyclic voltammetry and chronoamperometry. Consistent with the catalytic performances, CN-1Cu exhibited greater sensitivity towards the detection of paracetamol within the broad range of 38 µM to 3.64 mM and the study was carried out in the physiological pH ∼ 7.4.

Noble metal-free doped graphitic carbon nitride (g-C3N4) for efficient photodegradation of antibiotics: progress, limitations, and future directions.

Graphitic carbon nitride (g-C3N4) is well recognised as one of the most promising materials for photocatalytic activities such as environmental remediation via organic pollution elimination. New methods of nanoscale structure design introduce tunable electrical characteristics and broaden their use as visible light-induced photocatalysts. This paper summarises the most recent developments in the design ofg-C3N4 with element doping. Various methods of introducing metal and nonmetal elements into g-C3N4 have been investigated in order to simultaneously tune the material's textural and electronic properties to improve its response to the entire visible light range, facilitate charge separation, and extend charge carrier lifetime. The degradation of antibiotics is one of the application domains of such doped g-C3N4. We expect that this research will provide fresh insights into clear design methods for efficient photocatalysts that will solve environmental challenges in a sustainable manner. Finally, the problems and potential associated with g-C3N4-based nanomaterials are discussed. This review is expected to encourage the ongoing development of g-C3N4-based materials for greater efficiency in photocatalytic antibiotic degradation.

Construction of chlorine doped graphitic carbon nitride nanodisc for enhanced photocatalytic activity and mechanism insight

The development of high-performance doped graphite carbon nitride (g-C3N4) by one-step method has always been potential and yet demanding. Here, we designed a novel Cl doped nanodisc structure g-C3N4 (Cl(CN)) by one step HCl treatment, without calcination and adding any precursors during the preparation procedure. The photocatalytic activities of samples were assessed toward the hydrogen (H2) generation and degradation of rhodamine B (RhB) under simulated solar irradiation, of which the hydrogen production efficiency and degradation efficiency of Cl(CN) were 4 folds and 2.18 folds that of g-C3N4 (CN), respectively. The overwhelming photocatalytic performance of Cl(CN) was attributed to the synergy effect between the unique nanodisc morphology with high surface area and the regulation of the band structure by the Cl element. To exclude the effect of protonation, the CH3COOH, H2SO4, HNO3, KCl, NaCl and NH4Cl treatments were introduced to compare with HCl treatment. The position of doped Cl and its influence on the band gap as well as electronic structure over g-C3N4 were investigated by the density functional theory (DFT). In addition, the photocatalytic mechanism of as-prepared samples was further investigated and discussed in detail. This work provided a green and facile protocol for highly active and reusable g-C3N4 that can address the environmental issuers and energy challenges.

Coral-like potassium and phosphorous doped graphitic carbon nitride structures with enhanced charge and mass transfer dynamics toward photocatalytic hydrogen peroxide production and microbial disinfection

This study provided insight on the design of co-doped graphitic carbon nitride (g-C3N4) structures by using potassium dihydrogen phosphate (KH2PO4) as a promising material for the supply of potassium (K) and phosphorus (P) elements. The addition of KH2PO4 to the cyanuric acid-melamine complex (CM) solution stabilized its structure by coordinating potassium ions (K+) in the hexagonal pores and dihydrogen phosphate ions (H2PO4-) in dangling bonds on the edge sites. The resultant supramolecular structure (KP-CM) with a unique skeleton governed the polycondensation process, resulting in K and P co-doped g-C3N4 structures with a distinct coral-like morphology (KP-CN). Employing the KP-CM complex as a precursor could modify the optoelectronic behaviour of the photocatalysts via the synergistic effect of the co-doping process. It could also be beneficial in terms of economic considerations by increasing the catalyst synthesis yield. The resulting g-C3N4 showed a remarkable hydrogen peroxide (H2O2) production rate of 216 µmol L−1h−1 compared to the rate of the pristine sample of 137 µmol L−1h−1. It also exhibited significant photocatalytic antibacterial activity in Escherichia coli (E. coli) disinfection.

Charge carrier nonadiabatic dynamics in non-metal doped graphitic carbon nitride.

Graphitic carbon nitride (GCN) has attracted significant attention due to its excellent performance in photocatalytic applications. Non-metal doping of GCN has been widely used to improve the efficiency of the material as a photocatalyst. Using a combination of time-domain density functional theory with nonadiabatic molecular dynamics, we study the charge carrier dynamics in oxygen and boron doped GCN systems. The reported simulations provide a detailed time-domain mechanistic description of the charge separation and recombination processes that are of fundamental importance while evaluating the photovoltaic and photocatalytic performance of the material. The appearance of smaller energy gaps due to the presence of dopant states improves the visible light absorption range of the doped systems. At the same time, the nonradiative lifetimes are shortened in the doped systems as compared to the pristine GCN. In the case of boron doped at a carbon (B-C-GCN), the charge recombination time is very long as compared to the other two doped systems owing to the smaller electron-phonon coupling strength between the valence band maximum and the trap state. The results suggest B-C-GCN as the most suitable candidate among three doped systems studied in this work for applications in photocatalysis. This work sheds light into the influence of dopants on quantum dynamics processes that govern GCN performance and, thus, guides toward building high-performance devices in photocatalysis.

Synthesis and characterization of CuO@S-doped g-C3N4 based nanocomposites for binder-free sensor applications

This study presents the simultaneous exfoliation and modification of heterostructured copper oxide incorporated sulfur doped graphitic carbon nitride (CuO@S-doped g-C3N4) nanocomposites (NCs) synthesized via chemical precipitation and pyrolysis techniques. The results revealed that the approach is feasible and highly efficient in producing 2-dimensional CuO@S-doped g-C3N4 NCs. The findings also showed a promising technique for enhancing the optical and electrical properties of bulk g-C3N4 by combining CuO nanoparticles (NPs) with S-doped g-C3N4. The crystallite and the average size of the NCs were validated using X-ray diffraction (XRD) studies. Incorporation of the cubical structured CuO on flower shaped S-doped-g-C3N4 was visualized and characterized through XRD, HR-SEM/EDS/SED, FT-IR, BET, UV-Vis/DRS, PL, XPS and impedance spectroscopy. The agglomerated NCs had various pore sizes, shapes and nanosized crystals, while being photo-active in the UV-vis range. The synergistic effect of CuO and S-doped g-C3N4 as co-modifiers greatly facilitates the electron transfer process between the electrolyte and the bare glassy carbon electrode. Specific surface areas of the NCs clearly revealed modification of bulk S-doped g-C3N4 when CuO NPs are incorporated with S-doped g-C3N4, providing a suitable environment for the binder-free decorated electrode with sensing behavior for hazardous pollutants. This was tested for the preparation of a 4-nitrophenol sensor.

Theoretical Insight on Why N-Vacancy Promotes the Selective Co2 Reduction to Ethanol on Nimn Doped Graphitic Carbon Nitride Sheets

Theoretical Insight on Why N-Vacancy Promotes the Selective Co2 Reduction to Ethanol on Nimn Doped Graphitic Carbon Nitride Sheets

Platinum-silicon doped graphitic carbon nitride: A first principle calculation

Modifications of electronic and optical properties due to platinum, silicon, and platinum-silicon co-doping in the graphitic carbon nitride (g-C3N4) monolayer have been explored through density functional theory (DFT). The bandgap value of 1.2 eV has been obtained for the pristine g-C3N4 using generalized gradient approximation (GGA) employing Perdew-Burke-Ernzerhof (PBE) functional. The doping process has resulted in a fall in bandgap value. The platinum-silicon co-doping into g-C3N4 provides two new paths, C–N–Pt–N–C, and C–N–Si–N–C for the relocation of electron-hole couples across the adjacent heptazine rings. There is approximately a 25% increment (at 1 eV) in the optical conductivity in the infrared region after co-doping. The co-doped g-C3N4 also shows enriched light absorption. The work function is found to be decreased from 4.29 eV for the pristine g-C3N4 to 3.58 eV for the Pt/Si-co-doped g-C3N4. Hence, platinum-silicon co-doping should be considered as a suitable means to advance the photocatalytic performance of g-C3N4.

Synergistic Effect of Metal Complex and Dual Doped Graphitic Carbon Nitride for Superior Photocatalytic Hydrogen Evolution

The feeble photoinduced charge separation ability of pristine graphitic carbon nitride largely reduces its photocatalytic hydrogen evolution and thereby limits its practical application. Herein to ...

Computational identification of B substitutional doped C9N4 monolayer for electrocatalytic N2 reduction

Abstract Developing high-performance electrocatalysts with low overpotential and high selectivity for nitrogen reduction reaction (NRR) is vital to the sustainable production of ammonia (NH 3 ) at mild conditions. Recently, various B interstitial doped porous graphitic carbon nitride have been identified as efficient electrocatalysts for NRR, while the B substitutional doping has been rarely explored. In this work, three B doped C 9 N 4 monolayers have been designed (B C , B N , and B i n t ), and their efficiencies toward NRR are evaluated by performing comprehensive first-principles calculations. Our results clearly reveal that N 2 can be sufficiently activated on the B N and B i n t monolayers due to the ”acceptance-donation” interaction, and prefers to be reduced to NH 3 via the alternating mechanism. Particularly, B N monolayer shows superior catalytic activity with a rather low overpotential of 0.12 V comparing to B i n t monolayer (0.56 V). Moreover, we find that this proposed B N monolayer has not only great thermal and dynamic stabilities but also excellent suppression effect on the competitive hydrogen evolution reaction. These theoretical findings suggest that B substitutional doping strategy might be another direction for the design of high-performance B-based NRR eletrocatalysts.

Electrochemical determination of methylmercury via modulating bandgap of sulfur doped graphitic carbon nitride

Methylated mercury compounds are neurotoxins; they are ubiquitous in muddy sediments of water bodies under anaerobic conditions. A variety of coupled techniques such as capillary gas chromatography with inductively coupled plasma mass spectroscopy, or atomic fluorescence spectroscopy is used for detection of methylated mercury compounds. However, a sensitive analytical method for rapid screening of methylated mercury compounds is required. This work it was developed an electrochemical method for the detection of methylmercury in environmental samples using chemically modified Au electrodes via the bandgap modulation strategy. For the chemical modification, the sulfur-doped g-C3N4 was used as a starting material. The forbidden bandgap of the sulfur-doped g-C3N4 was regulated with urea and thiourea admixture fabricated by thermal polymerization at an optimal ratio (urea: thiourea = 3:1; hereafter UT-gCN (3:1). The UT-gCN (3:1) modified Au electrode was used for rapid detection of CH3Hg+ by differential pulse voltammetry (DPV) method operated at −0.80 V deposition potential, 800 s accumulation time in NaAc/HAc buffers (pH=5.0). The calibration curve of CH3Hg+ showed linearity within concentration range 0–25 ppb CH3Hg+ with 0.52 μA/ppb sensitivity and 0.175 ppb detection limit. The new electrochemical sensor is robust and interference-free to Cu2+, Cd2+, Pb2+, Bi3+, As3+. The efficiency of the UT-gCN(3:1) sensor can be replenished by protonation with HCl. Present results indicate the potential applications of UT-gCN (3:1) modified Au electrodes in the rapid detection of methylmercury in environmental samples.

Salt-air template synthesis of Na and O doped porous graphitic carbon nitride nanorods with exceptional photocatalytic H2 evolution activity

Photocatalyst fabrication process plays the central role in photocatalytic hydrogen (H2) evolution reaction. Herein, we synthesize Na+ functionalized porous graphitic carbon nitride nanorods (Na-CNNR) via a facile one-pot calcination method. The morphology and size of Na-CNNR are controllable by changing the amount of sodium salt; both sodium salt and air are essential to the unique structure and oxygen doping. The obtained Na-CNNR contains abundant oxygen in the graphitic carbon nitride (CN) plane. The optimized Na20-CNNR (20 wt% Na2S2O3•5H2O to dicyanamide) photocatalyst exhibits a high surface area with enhanced visible light absorption. Besides, Na20-CNNR displays fast charge transfer and high carrier separation rate characterized by photoluminescence (PL) spectroscopy and electrochemical test. Through time-resolved transient absorption spectra analysis, the trapped unreactive electron accumulation can be highly restrained, favoring efficient active electron de-trapping and transfer. The optimized Na20-CNNR sample exhibits the highest photocatalytic H2 evolution rate of 7.46 mmol/h/g under visible light irradiation (>400 nm, 100 mW/cm2), which is up to 85 times that of the bare CN and 27 times that of Na+ doped graphitic carbon nitride nanoparticles (Na20–CNNP). Meanwhile, the cyclability tests indicate that Na20-CNNR displays robust stability over 24 h.

Prediction of Band Gap Energy of Doped Graphitic Carbon Nitride Using Genetic Algorithm-Based Support Vector Regression and Extreme Learning Machine

Graphitic carbon nitride is a stable and distinct two dimensional carbon-based polymeric semiconductor with remarkable potentials in organic pollutants degradation, chemical sensors, the reduction of CO2, water splitting and other photocatalytic applications. Efficient utilization of this material is hampered by the nature of its band gap and the rapid recombination of electron-hole pairs. Heteroatom incorporation due to doping alters the symmetry of the semiconductor and has been among the adopted strategies to tailor the band gap for enhancing the visible-light harvesting capacity of the material. Electron modulation and enhancement of reaction active sites due to doping as evident from the change in specific surface area of doped graphitic carbon nitride is employed in this work for modeling the associated band gap using hybrid genetic algorithm-based support vector regression (GSVR) and extreme learning machine (ELM). The developed GSVR performs better than ELM-SINE (with sine activation function), ELM-TRANBAS (with triangular basis activation function) and ELM-SIG (with sigmoid activation function) model with performance enhancement of 69.92%, 73.59% and 73.67%, respectively, on the basis of root mean square error as a measure of performance. The four developed models are also compared using correlation coefficient and mean absolute error while the developed GSVR demonstrates a high degree of precision and robustness. The excellent generalization and predictive strength of the developed models would ultimately facilitate quick determination of the band gap of doped graphitic carbon nitride and enhance its visible-light harvesting capacity for various photocatalytic applications.

Dye Removal Ability of Pure and Doped Graphitic Carbon Nitride

Background:Rapid escalation in textile, paper, pesticides, pharmaceuticals and several other chemical based manufacturing industries due to amplification in human requirements have proportionately contributed to the extreme contamination of water ecosystem, resulted from the discharge of toxic pollutants from industries. Effluents from textile industries are comprised of coloured dyes like Rhodamine B, Methyl Orange, Methylene Blue and phenolic compounds which deserve special mention owing to their non-biodegradable, carcinogenic and severe detrimental nature. Urgent needs to ameliorate this fast declining environmental situation are of immense necessity in current scenario.Objectives:Objectives: In this regard, graphitic carbon nitride (GCN) is a distinguished material for water purification-based applications because of its exclusive characteristics making it highly prospective for degradation of toxic dyes from water by catalysis and adsorption techniques. GCN has been a material of conspicuous interest in recent times owing to its two dimensional sheets like structure with favourable surface area, and cost-effective synthesis approaches along with high production yield. This article presents a detail study of different aspects of GCN as a material of potential for water purification. Through extensive literature survey it has been shown that GCN is an effective material to be used in the fields of application. Several effective procedures like catalysis or adsorption for removal of dyes from water have been discussed with their basic science behind.Conclusions:This systematic effort shows that GCN can be considered to be one of the most efficient water purifier with further advantages arising from its easy and cost effective large scale synthesis.

Phosphorous doped g-C3N4 supported cobalt phthalocyanine: An efficient photocatalyst for reduction of CO2 under visible-light irradiation

The photoreduction of the green-house gas CO2 into carbon monoxide (CO) is a growing process due to the use of CO for the production of methanol in the Fischer-Tropsch process and the synthesis of many of the bulk chemicals. Here, we have synthesized phosphorous doped graphitic carbon nitride (P-g-C3N4) sensitized by the cobalt phthalocyanine complex for the molecular reduction of CO2 into CO under visible-light irradiation—the doping of phosphorous improved the stability as well as the harvesting of the visible region. The CoPc@P-g-C3N4 hybrid photocatalyst exhibited the highest efficiency for the photoreduction of CO2 with a high yield of 295 μmol-g−1 for CO under the experimental conditions. Also, hydrogen with low concentration was identified as a by-product under the experimental conditions. The photocatalyst had stability for six consecutive runs with negligible loss of the activity and no leaching of the cobalt content at the end of the sixth run of the photoreduction experiment. The stability of the photocatalysts is an advantage, which made it a suitable candidate for the current reaction system.

Hydrothermally exfoliated P-doped g-C3N4 decorated with gold nanorods for highly efficient reduction of 4-nitrophenol

Au nanorods (AuNRs) decorated phosphorus doped graphitic carbon nitride AuNRs/g-C3N(4-x)Px-NS catalyst have been designed and prepared by a facile hydrothermal approach, which is useful for the efficient reduction of nitroaromatics in aqueous solution using NaBH4− as reductant. A series of conventional characterizations like X-ray diffraction, scanning/transmission electron microscopy, Electron dispersive scanning, elemental mapping, Fourier transform infrared FT-IR, photoluminescence, and X-ray photoelectron spectroscopy were used to identify the physicochemical properties of AuNRs/g-C3N(4-x)Px-NS. The catalytic activities of AuNRs/g-C3N(4-x)Px-NS nanohybrid were studied under different conditions, including the amount of catalyst, NaBH4 dosage, and various temperatures for reduction of 4-nitrophenol (40 mL, 3 mM). Results showed that AuNRs/g-C3N(4-x)Px-NS nanohybrid exhibited superior catalytic performance with turning over (TOF) of 967 for 4-nitrophenol reduction, which is impressively high. In addition, the catalyst exhibited the best performance in reducing the 4-nitrophenol in the shortest possible time. The recyclability and stability of AuNRs/g-C3N(4-x)Px-NS catalyst was also examined.

DFT study of superhalogen and superalkali doped graphitic carbon nitride and its non-linear optical properties.

DFT calculations are carried out to investigate nonlinear optical (NLO) properties of superhalogen (BCl4) and superalkali (NLi4) doped graphitic carbon nitride (GCN). It is noted that the geometries of doped GCN are sufficiently stable. The energy gap for GCN is 3.89 and it reduces to 0.53 eV in our designed molecule G4. Change in the dipole and transition dipole moment is observed along with small transition energies which are responsible for higher hyperpolarizabilities. Doped GCN has larger first and second hyperpolarizabilities which are basic requirements for NLO response. The second hyperpolarizability of GCN enhances from 1.59 × 104 to 2.53 × 108 au when doping with BCl4 and NLi4. TD-DFT calculations show the absorption maxima of doped GCN range from 700 nm to 1350 nm. EDDM analysis provides information on electronic distribution from excited to ground state. All these consequences show doped GCN can be a promising NLO material.