Properties Of Graphitic Carbon Nitride Research Articles

Simultaneous dopants and defects synergistically modulate the band structure of CN in Z-scheme heterojunctional photocatalysts for simultaneous HER and OER production

Enhancing solar-driven oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) is critical for advancing renewable energy solutions and mitigating global CO2 emissions. In this study, we employed a blend of experimental and theoretical approaches to improve the properties of graphitic carbon nitride (CN). This improvement entailed the introduction of isolated boron dopants and nitrogen deficiency into CN, achieved via a straightforward calcination process with sodium borohydride, followed by the integration of ultrathin iron phthalocyanine (FePc) connected through phosphate groups. The synthesized nanocomposite, FePc/P–BCNN, exhibited exceptional photocatalytic efficacy in OER and HER, reaching production rates of 915.4 μmol h−1 and 99.5 μmol h−1, marking a substantial enhancement-nearly 8- & 9-fold over traditional CN materials under visible light. This remarkable efficiency stems from a deliberate modification of the conduction and valence bands through the incorporation of B-dopants and N-defects, thereby fine-tuning the band structure for improved OER and HER performance. Furthermore, the potential of ultrathin metal phthalocyanine structures, offering multiple single-atom active sites, and showcased a sustainable approach for photocatalytic OER and HER. The rapid charge separation, propelled by a Z-scheme charge transfer mechanism, facilitated through a dimensionally matched strategy contributes novel insights into the field of sustainable energy conversion technologies.

Surface modification of graphitic carbon nitride nanoparticles with B, O and S doping/carbon vacancy for efficient dehydrogenation of sodium borohydride in methanol

Herein, the surface properties of graphitic carbon nitride (GCN) with sulphur(S), boron (B) and oxygen (O) dopants were improved. The heteroatom-doped metal-free GCN exhibited both rich surface functional groups and a carbon defect structure. These metal-free catalysts were used to obtain hydrogen (H2) from the sodium borohydride (SB) methanolysis for the first time. Compared to GCN, S, B, and O doped GCN catalyst obtained showed a 2.2-fold improvement in H2 production. HGR value obtained with B, O and S doped GCN (10 mg) via SB of 2.5% was 9166 ml min −1g−1. XPS, SEM-EDX, TEM, FTIR, and XRD analyses were used for the structural properties of catalysts. The activation energy (Ea) for B, O and S doped GCN was 28.89 kJ mol−1.

CO2 gas sensing properties of graphitic carbon nitride (g-C3N4) thin films

CO2 gas sensing properties of graphitic carbon nitride (g-C3N4) thin films

Effective strategies for improved optoelectronic properties of graphitic carbon nitride: A review

Graphitic carbon nitride (g-C3N4) is a promising two-dimensional material having a nanostructured morphology and non-toxic nature that is metal-free and environmentally friendly. Optical, electronic, and chemical sciences are expanded by the many applications of g-C3N4. However, g-C3N4 offers lower absorbance of solar light, transmitting the higher wavelengths of visible light and the near-infra red and infrared light, restricting its utility for solar light-dependent applications such as photocatalysis, photovoltaics, water splitting, dye degradation, and deterioration of harmful organics. Due to its enhanced thermal, hydrothermal and chemical stability, compelling band gap structure (2.7 eV), and eco-friendliness, g-C3N4 has become a powerful substitute for metal and semiconductor-based catalysis. In this review, we highlight the synthesis and modifications of g-C3N4 relevant to certain important applications. We also computed certain recent modifications and effective strategies to improve the optoelectronic properties of g-C3N4 and thus arrived finally at interesting avenues for future research.

Graphitic carbon nitride nanosheets as promising candidates for the detection of hazardous contaminants of environmental and biological concern in aqueous matrices.

Monitoring of pollutant and toxic substances is essential for cleaner environment and healthy life. Sensing of various environmental contaminants and biomolecules such as heavy metals, pharmaceutics, toxic gases, volatile organic compounds, food toxins, and pathogens is of high importance to guaranty the good health and sustainable environment to community. In recent years, graphitic carbon nitride (g-CN) has drawn a significantamount of interest as a sensor due to its large surface area and unique electrochemical properties, low bandgap energy, high thermal and chemical stability, facile synthesis, nontoxicity, and electron rich property. Furthermore, the binary and ternary nanocomposites of graphitic carbon nitride further enhance their performance as a sensor making it a cost effective, fast, and reliable gadget for the purpose, and opens a wide area of research. Numerous reviews addressing a variety of applications including photocatalytic energy conversion, photoelectrochemicaldetection, and hydrogen evolution of graphitic carbon nitride have been documented to date. But a lesser attention has been devoted to the mechanistic approaches towards sensing of variety of pollutants concerned with environmental and biological aspects. Herein, we present the sensing features of graphitic carbon nitride towards the detection of various analytes including toxic heavy metals, pharmaceuticals, phenolic compounds, nitroaromatic compounds, volatile organic molecules, toxic gases, and foodborne pathogens. This review will undoubtedly provide future insights for researchers working in the field of sensors, allowing them to investigate the intriguing graphitic carbon nitride material as a sensing platform that is comparable to several other nanomaterials documented in the literature. Therefore, we hope that this study could reveal some intriguing sensing properties of graphitic carbon nitride, which may help researchers better understand how it interacts with contaminants of environmental and biological concern. Graphitic carbon nitride Nanosheets as Promising Analytical Tool for Environmental and Biological Monitoring of Hazardous Substances.

Formation and antibacterial properties of graphitic carbon nitride

Graphitic carbon nitride (g-C3N4 ) was synthesized by pyrolysis of thiocarbamide and a subsequent polymerization of its products at 500 °С. After grinding the synthesized material, aqueous suspensions with the concentrations of the particles of 100–300 μg/ml were prepared from it. The antibacterial activity of the material under irradiation with the LED’s visible light for 60–120 min was confirmed for Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

Effects of g-C3N4 on mechanical and thermal properties of epoxy nanocomposites

Polymer nanocomposites have been created by incorporating inorganic nanoparticles as additives into polymer systems, resulting in polymer nanocomposites having multifunctional, high-performance polymer properties, as opposed to typical materials packed polymeric materials. Using the liquid casting process, this research focuses on the thermal and mechanical properties of graphitic carbon nitride (g-C3N4) nanofiller reinforced epoxy nanocomposites. The g-C3N4 reinforced epoxy hybrid nanocomposites developed by varying different weight fraction (0 %, 0.5 %, 1 %, 1.5 % and 2 %). The morphological behaviour of produced nanocomposites is investigated using a Transmission Electron Microscope (TEM). Scanning Electron Microscope confirms cluster-free uniform dispersion of fillers in an epoxy matrix (SEM). Tensile, flexural, and water absorption characteristics of epoxy nanocomposites were investigated as a function of the weight percent of g-C3N4 nanofiller.

Piezoelectric induced reverse photocatalytic performances of carbon nitride with different structures

The piezoelectric properties of graphitic carbon nitride with different structures follow the order PTI > melon > PHI, and the melon and PHI showed reverse activities in the photocatalytic and piezoelectric assisted photocatalytic reactions.

Point‐Defect Engineering: Leveraging Imperfections in Graphitic Carbon Nitride (g‐C3N4) Photocatalysts toward Artificial Photosynthesis (Small 48/2021)

Point-Defect Engineering Solar energy is an abundant source of renewable energy, which can be harnessed via photocatalysis. Of which, point-defect engineering is a robust strategy to tune physico-chemical properties of graphitic carbon nitride toward enhanced photocatalytic H2O splitting, CO2 and N2 reduction. A comprehensive review is presented by Wee-Jun Ong and co-workers in article number 2006851.

Tuning the surface and optical properties of graphitic carbon nitride by incorporation of alkali metals (Na, K, Cs and Rb): Effect on photocatalytic removal of organic pollutants

Alkali metals have been known for their intercalation properties and can be employed for the separation of stacking in sheet-like materials. In this work, alkali metals (Na, K, Rb and Cs) have been systematically incorporated in varying concentrations in g-C3N4 sheets and their effect on resulting optical, surface and photocatalytic properties have been explored in detail. It was observed that the optical, electronic and surface properties of g-C3N4 were altered upon the incorporation of different alkali metal ions. The band gap and specific surface area of resulting materials were decreased as compared to the pristine g-C3N4. In addition, the alkali metal incorporation in g-C3N4 sheets showed the formation of cyanide groups and nitrogen vacancies in the resulted materials. Further, the photocatalytic activity of g-C3N4 and alkali metal incorporated g-C3N4 was calculated by studying the degradation of acid red 94 dye under visible light irradiation. It was observed that the photocatalytic activity of pristine g-C3N4 sheets was decreased with an increase in the concentration of alkali salt used during the synthesis of alkali metal incorporated g-C3N4. This decrease in the activity could arise due to the decreased surface area, detrimental amount of nitrogen vacancies and high concentration of alkali metal ions incorporated in the structural framework of g-C3N4 sheets. This work provides a unique example of the adverse effect of alkali metal ions on photocatalytic activity of g-C3N4 and paves future directions for the improvement of the performance of g-C3N4 based materials.

Ab initio study of photocatalytic characteristics of graphitic carbon nitride assisted by oxalic acid

Using density functional theory, structural, electronic, and optical properties of GCN (graphitic carbon nitride) and OAGCN (graphitic carbon nitride combined with oxalic acid) were studied. By comparing HOMOs and LUMOs and excitonic binding energies, OAGCN has lower photoinduced electron-hole recombination rate than GCN. VBM and CBM levels of GCN and OAGCN were calculated, which shows that for GCN, only the electron at CBM contributes to produce radicals for removing pollutants, and for OAGCN, both the electron at CBM and the hole at VBM contribute to produce radicals for removing pollutants. In total, it can be said that OAGCN has higher photocatalytic activity than GCN.

Carbon ring and molecular scaffold co-doped g-C3N4 heterostructural nanosheets for highly efficient hydrogen evolution

Copolymerization is an efficient method to modulate the intrinsic properties of graphitic carbon nitride (g-C3N4). Herein, carbon ring and stereo molecular scaffold co-doped g-C3N4 heterostrcutural nanosheets are constructed for simultaneously enhanced photocatalytic hydrogen evolution under ordinary pressure. The carbon ring changes the in-plane connection of g-C3N4 by the sp2-hybridized CN bonds, extending the delocalization of π electrons. The stereo molecular scaffold loses the interlayer stacking of bulk g-C3N4 for easier exfoliation. The synergistic effect of the above two aspects can greatly improve the photocatalytic performance of AGCN. After thermal exfoliation, the highest photocatalytic hydrogen generation activity of A0.2G0.3CN-E sample is 12.9 times higher than that of MCN. This work provides a strategy to design g-C3N4 photocatalysts with enhanced photocatalytic activity by using synergistic effect.

NiO Decorated Ti/TiO2 Nanotube Arrays (TiO2NT)/TiO2/g-C3N4 Step-Scheme Heterostructure Thin Film Photocatalyst with Enhanced Photocatalytic Activity for Water Splitting

A new strategy to enhance the photocatalytic properties of graphitic carbon nitride is reported via constructing an effective NiO decorated Ti/TiO2NT/TiO2/g-C3N4 S-scheme heterostructure photocatalyst thin film (Ti/TiO2NT/TiO2/g-C3N4/NiO). This thin film photocatalyst can separate hydrogen gas and oxygen gas into different sides of the Ti substrate. Owing to the synergistic effect of the NiO as co-catalyst and the formation of Step-scheme (S-scheme) heterojunction between g-C3N4 and TiO2, the electrons and holes were successfully separated to their opposing active centers, which is beneficial to inhibiting the recombination of the charge carriers. The gas evolution rate of Ti/TiO2NT/TiO2/g-C3N4/NiO is 7.97 μmol h−1 cm−2 under the irradiation of high-pressure mercury lamp, which was 3 and 1.3 times as high as that of the Ti/TiO2NT/g-C3N4 and Ti/TiO2NT/TiO2/g-C3N4, respectively. Firstly, benefiting from the well-matched band structure, a direct S-scheme Ti/TiO2NT/g-C3N4 heterojunction thin film is constructed easily driven by the built-in electric field across the Ti/TiO2NT/g-C3N4 interface. Furthermore, the introduction of the TiO2 layer on the TiO2NT will broaden light absorption range and increase the heterojunction area, which in turn conduces to effective charge separation. In addition, NiO as a co-catalyst cannot only accelerate the charge separation but also provide plentiful catalytic sites and decompose H2O2 produced by g-C3N4. The thin film photocatalysts can be recycled again, which is different from traditional powdered photocatalysts. This work constructs a NiO decorated Ti/TiO2NT/TiO2/g-C3N4 S-scheme heterostructure photocatalyst thin film, and provides a new insight to promote photocatalytic activity of g-C3N4 under the synergetic impact of S-scheme heterostructure and NiO co-catalyst. A novel NiO decorated Ti/TiO2NT/TiO2/g-C3N4 S-scheme heterostructure photocatalyst thin film was fabricated to enhance photocatalytic activity for water splitting.

Molecular topological indices-based analysis of thermodynamic properties of graphitic carbon nitride

Graphitic carbon nitride $$({\text {g-C}}_{3}{\text {N}}_{4})$$ has become a new interdisciplinary research hot spot due to its metal-free and visible-light-responsive nature along with alluring electronic band structure and high physicochemical stability. This fascinating semiconductor conjugated polymer is considered a feasible material for harvesting clean and inexhaustible solar energy in the field of environmental remediation and energy applications. Chemical graph theory plays an important role in modeling and designing the chemical structure of complex compounds. The molecular topological indices are the numerical invariants of a molecular graph and are very useful for predicting the reactivity of respective compound. In this paper, we studied the chemical graph of crystalline graphitic carbon nitride, i.e., $$({\text {g-C}}_{3}{\text {N}}_{4})$$ , via degree-based topological indices such as general Randic index, atom bond connectivity index, geometric arithmetic index and Zagreb-type indices. Curve fitting between the calculated thermodynamic properties and topological indices was done together with the numerical and graphical representation of computed results. This mathematical framework of graphitic carbon nitride based on topological indices presents a comprehensive picture of potentially valuable thermodynamic properties such as entropy and enthalpy which could be useful in structural modification of $$({\text {g-C}}_{3}{\text {N}}_{4})$$ for specific application.

A theoretical study on the influence of non-metal (B, C, N, O, F) doping on the electronic and optical properties of graphitic carbon nitride (g-C3N4)

A robust and accurate tight-binding quantum chemical method (GFN2-xTB) was performed to study the electronic and optical properties of graphitic carbon nitride (g-C3N4) and g-C3N4 modified with non-metal atom (B, C, N, O, F). The vertical ionization potential, electron affinity and global electrophilicity indexes were calculated and analyzed. The obtained results show that the doping of B, C, N, O or F atom onto the surface g-C3N4 is favorable in terms of formation energy. The introduction of non-metal atoms raises the Lewis acidity of g-C3N4. The calculated UV-VIS spectra show that the doping of non-metal atoms increases the absorption intensity of visible light compared to the pure g-C3N4.

Using C-Doping to Identify Photocatalytic Properties of Graphitic Carbon Nitride That Govern Antibacterial Efficacy

Graphitic carbon nitride (g-C3N4) is a promising photocatalyst for bacterial disinfection. Herein, carbon doping (C-doping) was employed to manipulate g-C3N4 physicochemical properties and demonstr...

Photoelectrochemical Studies on Metal-Doped Graphitic Carbon Nitride Nanostructures under Visible-Light Illumination

Recently, the engineering of optical bandgaps and morphological properties of graphitic carbon nitride (g-C3N4) has attracted significant research attention for photoelectrodes and environmental remediation owing to its low-cost synthesis, availability of raw materials, and thermal physical–chemical stability. However, the photoelectrochemical activity of g-C3N4-based photoelectrodes is considerably poor due to their high electron–hole recombination rate, poor conductivity, low quantum efficiency, and active catalytic sites. Synthesized Ni metal-doped g-C3N4 nanostructures can improve the light absorption property and considerably increase the electron–hole separation and charge transfer kinetics, thereby initiating exceptionally enhanced photoelectrochemical activity under visible-light irradiation. In the present study, Ni dopant material was found to evince a significant effect on the structural, morphological, and optical properties of g-C3N4 nanostructures. The optical bandgap of the synthesized photoelectrodes was varied from 2.53 to 2.18 eV with increasing Ni dopant concentration. The optimized 0.4 mol% Ni-doped g-C3N4 photoelectrode showed a noticeably improved six-fold photocurrent density compared to pure g-C3N4. The significant improvement in photoanode performance is attributable to the synergistic effects of enriched light absorption, enhanced charge transfer kinetics, photoelectrode/aqueous electrolyte interface, and additional active catalytic sites for photoelectrochemical activity.

Tailoring the properties of g-C3N4 with CuO for enhanced photoelectrocatalytic CO2 reduction to methanol

In the present work, the physico-chemical and photoelectrocatalytic (PEC) carbon dioxide (CO2) reduction to methanol properties of graphitic carbon nitride (g-C3N4) were enhanced by the incorporation of CuO. The XRD, XPS, TEM, FESEM, UV–vis and photoluminescence (PL) spectroscopy techniques were used to characterize the synthesized g-C3N4 and CuO/g-C3N4 photocatalysts. The fabricated CuO/g-C3N4/carbon paper photocathode showed ∼10.0 times enhanced photocurrent response and 5.3 times enhanced incident photon to current efficiency (IPCE) than the g-C3N4/carbon paper photocathode under CO2 atmosphere in aqueous NaHCO3 electrolyte solution on 470 nm light irradiation. The higher IPCE of CuO/g-C3N4/carbon paper photocathode was attributed to the higher absorption of the incident visible light which results in efficient electron (e−-hole (h+) pair generation and charge transfer for the PEC conversion of CO2. The production of methanol in aqueous phases was analysed and found to be 4.1 and 2.6 times higher by CuO/g-C3N4/carbon paper photocathode than g-C3N4/carbon paper and CuO/carbon paper photocathodes, respectively. The CuO/g-C3N4/carbon paper photocathode showed Faradaic efficiency and quantum efficiency of 75 % and 8.9 %, respectively for the production of methanol. The plausible mechanism for the production of methanol by CuO/g-C3N4/carbon paper photocathode by PEC reaction was also discussed.

Preparation and characterization of ion beam sputtered graphitic carbon nitride thin film

Ion beam sputtering is a versatile technique to create nanostructured thin films with precise control over process parameters. We report the properties of graphitic carbon nitride (g-C3N4) thin films deposited by ion beam sputtering. Ion beam analysis methods including Rutherford Backscattering Spectrometry (RBS), Nuclear Reaction Analysis (NRA) and Particle Induced X-ray Emission (PIXE) were used for quantitative determination of composition, thickness, elemental depth profile and trace, major elements and impurities. It was found that by directly using compressed g-C3N4 powders as the sputter target material and tuning the process parameters, g-C3N4 thin films with well controlled deposition rate were obtained. Post-annealing above 250 °C under argon atmosphere for 30 min was needed to recrystallize the g-C3N4 nanostructure. Our results suggest that ion beam sputtering technique is a promising method to obtain uniform and high-quality g-C3N4 thin films.

Effect of Pyrolysis Conditions on the Physicochemical Properties of Graphitic Carbon Nitride for Visible-Light-Driven Photocatalytic Degradation

Effect of Pyrolysis Conditions on the Physicochemical Properties of Graphitic Carbon Nitride for Visible-Light-Driven Photocatalytic Degradation