Phosphorus-doped g-C3N4 Research Articles

Phosphorus-Doped g-C3N4 Induces Self-Polarization PVDF for High-Performance Triboelectric Nanogenerator As Wearable Power Sources

In recent years, the requirement for wearable electronic energy has become increasingly popular, which can be seen from the creation of numerous energy harvesters and storage devices. Among them, a new type of energy harvesting technology named triboelectric nanogenerator (TENG) has gradually matured for nearly ten years. Increasing the output performance by enhancing the surface charge of the TENG is what most researchers have focused on recently. There are several ways such as changing the surface structures, improving the dielectric constant and spontaneous polarization, which is related to this work. Some papers mention that filling nanoparticles or adding 2-dimensional material will induce PVDF self-polarization to the beta phase, making it a highly electronegative state. Moreover, adding high electronegative atoms will also change the state of the PVDF. Therefore, we synthesize the PVDF film by adding phosphorus-doped g-C3N4 (PCN) in order to enhance the output performance. By introducing the P atom into the matrix of g-C3N4 via an annealing process, the P atom in g-C3N4 not only increases the electronegativity of the film surface but also induces PVDF to a polarized crystal b phase for absorbing more positive charges. Consequently, the TENG with PVDF/PCN displays a remarkable improvement in output performance compared to the pristine PVDF-based TENG with more than a 100 V increase. Furthermore, the flexibility and durability of PVDF/PCN thin film have the potential to be widely used in self-powered wearable sources. Figure 1

Methyl contributes to the directed phosphorus doping of g-C3N4: pH-dependent selective reactive oxygen species enable customized degradation of organic pollutants

In the photocatalytic degradation process, constructing a controllable composite oxidation system with radicals and nonradicals to meet the requirement for efficient and selective degradation of diverse pollutants is significant. Herein, a methylated and phosphorus-doped g-C3N4 (NPEA) can exhibit selective radical and nonradical species formation depending on the pH values. The NPEA can spontaneously switch the production of active species according to the pH value of the reaction system, exhibiting steady-state concentrations of ·O2− for 11.83 × 10−2 µmol L−1 s−1 (with 92.7 % selectivity) under alkaline conditions (pH = 11), and steady-state concentrations of 1O2 for 5.18 × 10−2 µmol L−1 s−1 (with 88.7 % selectivity) under acidic conditions (pH = 3). The NPEA exhibits stability and universality in the degradation of pollutants with rate constant for sulfamethazine (k = 0.261 min−1) and atrazine (k = 0.222 min−1). Moreover, the LC-MS and Fukui function demonstrated that the NPEA can tailor degradation pathways for pollutants, achieving selective degradation. This study offers a comprehensive insight into the mechanism of the photocatalytic oxidation system, elucidating the intricate interplay between pollutants and reactive oxygen species.

Phosphorus-Doped Hollow Tubular g-C3N4 for Enhanced Photocatalytic CO2 Reduction.

Photocatalytic CO2 reduction is a tactic for solving the environmental pollution caused by greenhouse gases. Herein, NH4H2PO4 was added as a phosphorus source in the process of the hydrothermal treatment of melamine for the first time, and phosphorus-doped hollow tubular g-C3N4 (x-P-HCN) was fabricated and used for photocatalytic CO2 reduction. Here, 1.0-P-HCN exhibited the largest CO production rate of 9.00 μmol·g-1·h-1, which was 10.22 times higher than that of bulk g-C3N4. After doping with phosphorus, the light absorption range, the CO2 adsorption capacity, and the specific surface area of the 1.0-P-HCN sample were greatly improved. In addition, the separation of photogenerated electron-hole pairs was enhanced. Furthermore, the phosphorus-doped g-C3N4 effectively activated the CO2 adsorbed on the surface of phosphorus-doped g-C3N4 photocatalysts, which greatly enhanced the CO production rate of photocatalytic CO2 reduction over that of g-C3N4.

Two-dimensional RGO-bridge S-scheme phosphorus-doped g-C3N4/Bi5O7I van der Waals heterojunctions for efficient visible-light photocatalytic treatment of real pharmaceutical wastewater

Two-dimensional RGO-bridge S-scheme phosphorus-doped g-C3N4/Bi5O7I van der Waals heterojunctions for efficient visible-light photocatalytic treatment of real pharmaceutical wastewater

Preparation of phosphorus-doped mesoporous g-C3N4 and its photocatalytic degradation of tetracycline hydrochloride

P-doped tunnel-shaped carbon nitride is prepared for the first time using phosphonitrilic chloride trimer as P source and SBA-15 as template. The optimization experiments reveal that 20% P doped tunnel-shaped carbon nitride exhibited the best tetracycline hydrochloride (TC) degradation performance under visible light irradiation. The degradation rate constant is 0.23367 min−1, which is around 3 and 30 times faster than that of carbon nitride without P doping (0.07223 min−1) and without SBA-15 as template (0.00078 min−1). Radical capture experiment shows that h+ and ∙O2− are the main reactive radicals in the photocatalytic degradation process. The doped P element can increase the formation rate of ∙O2− and reduce the combination of photogenerated electron-hole pairs due to the presence of electron capture centers. The photocatalytic mechanism of P-doped tunnel-shaped carbon nitride is proposed, providing experimental data and theoretical basis for the practical application in polluted wastewater.

Direct injection of electrons into Cu active sites from porous phosphorus-doped g-C3N4 for enhanced Fenton-like performance

Copper oxides were supported on porous P-doped g-C3N4 (Cu/p-PCN) by a stepwise calcination process. Elemental analysis, XPS, and ESR results show that P atoms enter the network of g-C3N4, and the thus-fabricated configuration could provide additional electrons for the conjugated system of g-C3N4. As verified by TEM, XRD, XPS, and FTIR results, copper is mainly present as oxides on the catalyst surface and undergoes Cu-π interactions with porous P-doped g-C3N4 (p-PCN). During the reaction, unpaired electrons in p-PCN can be injected into the Cu active sites, prompting the decomposition of H2O2 into hydroxyl radicals (•OH). The degradation begins with the activation of H2O2 into •OH radicals by the Cu(I) active center. The depleted Cu(I) centers are then regenerated by electron injection from P atoms rather than by the reaction between H2O2 and Cu(I). Thus, the catalyst performance and H2O2 utilization are greatly enhanced. Equally significantly, the porous structure of Cu/p-PCN also contributes appreciably to its performance by increasing the specific surface area and active sites. Cu/p-PCN exhibits better performance than many reported catalysts in similar conditions, robust resistance to interference from various ions, high degradation efficiency over a wide pH range, and excellent degradation ability for various pollutants.

A facile and green synthesis of Mn and P functionalized graphitic carbon nitride nanosheets for spintronics devices and enhanced photocatalytic performance under visible-light

Manganese and phosphorus co-doped, graphitic carbon nitride (g-C3N4) nanosheet (Mn/P-g-C3N4) is prepared by facile and green calcination process of melamine (C3H6N6), manganese chloride tetrahydrate (MnCl2·4H2O), and ammonium dihydrogen phosphate ((NH4)H2PO4). The Mn/P co-doping significantly enhances magnetic values compared to pristine-g-C3N4, phosphorus-doped g-C3N4 (P-g-C3N4), and manganese-doped g-C3N4 (Mn-g-C3N4). We find that Mn/P-g-C3N4 is a half-metallic ferromagnetic material having a magnetic moment and Curie temperature of 4.51 μB and ∼ 800 K, respectively. The ultraviolet–visible (UV–vis) absorption spectrum of Mn/P-g-C3N4 reveals superior absorption in broader wavelength compared to pristine-g-C3N4, P-g-C3N4, and Mn-g-C3N4. The methyl orange degradation efficiency of Mn/P-g-C3N4 photocatalyst is 94 %, which is three times more than that of pristine-g-C3N4 (29 %) and more significant than the P-g-C3N4 (46 %) and Mn-g-C3N4 (58 %). Furthermore, density functional theory (DFT) calculation explains the origin of high magnetic behavior, the boosted photocatalytic efficiency of Mn/P-g-C3N4, and the essential material properties like structure, bandgap, the density of states (DOS), and atomic level interaction. This work may be helpful for reasonably designing ferromagnetic material for spintronics devices and boosting visible-light (VL) photocatalytic performance for environmental remediation.

Self-assembly synthesis of hollow phosphorus-doped graphitic carbon nitride microboxes for the photodegradation of organic pollutants.

The rational design of photocatalysts with efficiency and stability is highly desirable but remains challenging. Here, we report a supramolecular self-assembly strategy to construct hollow phosphorus-doped g-C3N4 microboxes (PCNMs). Considering the effects of multiple parameters on the structure and activity of samples, the orthogonal design is innovatively introduced to optimize technology parameters for screening high-performance g-C3N4. Under visible light irradiation (λ ≥ 420 nm), rhodamine B (RhB, 4 mg L-1) is completely degraded in just 80 seconds in the presence of the optimal PCNM. The kinetic rate constant of RhB degradation with the PCNM is 3.4633 min-1, demonstrating unprecedented activity that is about 112 times higher than that of bulk g-C3N4 (0.0309 min-1) synthesized by direct polycondensation of melamine. Additionally, the optimal PCNM also shows enhanced degradation efficiency for tetracycline. The outstanding properties are primarily attributed to the hollow architecture, high specific surface area, and phosphorus doping. This work advances the design of photocatalysts correlating various factors, opening an avenue for optimizing photocatalytic synthesis and activity.

The Construction of Phosphorus-Doped g-C3N4/Rh-Doped SrTiO3 with Type-II Band Alignment for Efficient Photocatalytic Hydrogen Evolution.

It is of great importance to promote charge separation in photocatalysts for enhanced photocatalytic activity under visible light irradiation. In this work, a type-II heterostructured photocatalyst was constructed by compositing phosphorus-doped g-C3N4 (P-CN) and Rh-doped SrTiO3 (Rh-STO) via a thermal calcination treatment. A series of characterizations were conducted to investigate the structure of heterostructured P-CN/Rh-STO. It was found that Rh-STO interacted with in situ generated P atoms from the decomposition of P-CN during the calcination process, thus leading to the formation of heterojunction of P-CN/Rh-STO. Compared with the single component, i.e., P-CN or Rh-STO, the obtained P-CN/Rh-STO showed superior photocatalytic activity to that of both P-CN and Rh-STO due to the effective charge separation across the heterojunction between P-CN and Rh-STO.

Electron rich P doped g-C3N4 for photodegradation of 2,4-dichlorophenoxyacetic acid under visible light by improving oxygen adsorption: Performance and catalytic mechanism

In the paper, the phosphorus-doped g-C3N4 (PCN) photocatalyst was synthesized by thermal polycondensation, and its photocatalytic performance and mechanism for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation were investigated. Element composition and bonding analysis identified that P atoms replaced some carbon atoms in g-C3N4. Optical property and photoelectrochemistry analysis showed that P doping weakened the bandgap of g-C3N4 and enhanced the rate of photogenerated charge migration. The density of states calculated by density functional theory (DFT) indicated that the above results were due to the formation of impurity levels by P doping. The PCN with the best performance possessed 5 times the photodegradation rate for 2,4-D compared with pure g-C3N4. ·O2– and h+ played important roles during the photodegradation of 2,4-D. The difference charge densities and O2 adsorption model showed that P doping changed the catalytic reaction site and promoted O2 adsorption, thus generating more ·O2–.

Efficient photocatalytic H2 production and ofloxacin degradation based on heterodimensional Z-scheme P-C3N4/MIL-88A(Fe) heterojunctions

The production of effective photocatalyst to generate H2 and eliminate pollutants is still a challenge. A simple solvothermal approach is demonstrated for synthesizing a coupled P-C3N4/MIL-88A(Fe) composite wherein two-dimensional phosphorus-doped g-C3N4 nanosheets are attached to three-dimensional MIL-88A. The P-CN/MIL-88A composite shows superior photocatalytic ability with a high hydrogen generation rate of 34.53 mmol/(g·h) and an ofloxacin degradation rate of 95.6%. The H2 evolution rate of the composite is approximately 38.3 times that of bulk g-C3N4 (B-CN). The enhancement mechanisms resulting in high efficiency and adaptability are attributed to the Z-scheme (2D/3D) P-CN/MIL-88A heterojunction, which has unique synergistic interface properties, good photoinduced electron mobility, and good electron-hole pair separation ability. This work provides insights into the design of 2D/3D heterostructure photocatalysts for highly efficient and simultaneous photocatalytic H2 production and antibiotic degradation.

Advanced Sensing of Antibiotics with Sr@Se Flower-Like Structure on Phosphorus-Doped g-C3N4 Composite: Application towards Detection of Chloramphenicol in Food Samples

In this article, we developed specific sensing of chloramphenicol (CAP) using strontium selenium nanoflower-adorned phosphorus-doped graphitic carbon nitride (Sr@Se/PGCN) nanocomposite. The synthesized Sr@Se/PGCN nanocomposite was characterized using spectrophotometric techniques. Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), and Differential Pulse Voltammetry (DPV) were used to examine the electrochemical performance of Sr@Se/PGCN nanocomposite. The Sr@Se/PGCN composite shows excellent performance with a linear range of 5–450 µM and an LOD of 2.7 nM. Furthermore, the present electrochemical CAP sensor exhibited high sensitivity, good stability, exceptional reproducibility, and an excellent recovery rate in real food samples.

Improved ionic organic pollutant degradation under visible light by Ag SPR-promoted phosphorus-doped g-C3N4/AgBr/Bi2WO6 with excellent charge transfer capacity and high surface area

Graphite carbon nitride (g-C3N4) has a strong photocatalytic capability to degrade ionic organic compounds due to its unique electrical structure with numerous marginal amino groups. A photocatalyst was fabricated via a facile in-situ sedimentation–calcine–hydrothermal method by anchoring AgBr and Bi2WO6 onto the framework of phosphorus-doped g-C3N4 (PCAB). The photocatalyst has been proven to have good photocatalytic degradation effect on different ionic organic pollutants. The removal rate of tetracycline, the target pollutant, can reach 99.2%, which was 1.83 times higher than that of g-C3N4 within 60 min under visible light. Moreover, the degradation rates of dyes containing azo bonds and -SO3H can reach 100% within 20 min, as determined by the electrical relationship between the catalyst and the dye. The excellent performance can be attributed to the synergistic effect of the formation of mid-gap in g-C3N4 after phosphorus doping, improvements in charge carrier transfer and the low recombination rate based on the construction of dual Z-scheme heterojunction and Ag bridge. In addition, cycling experiments and characterizations illustrated the high stability and reusability of PCAB. The main active species during photocatalytic process was·O2−, whereas h+ and·OH played a minimal role. Ultimately, a dual Z-scheme mechanism was proposed to explain the photocatalytic reaction.

Long-lasting photocatalytic activity of trace phosphorus-doped g-C3N4/SMSO and its application in antibacterial ceramics

Conventional photocatalysts generate numerous active species—primarily hydroxyl radicals (•OH)—under solar light excitation to exert photocatalytic activity for especially antibacterial effects. However, the light dependence limits their competitiveness against other antimicrobial materials since they do not work at night. Herein, a P-g-C3N4/Sr2MgSi2O7:Eu2+,Dy3+ (P-g-C3N4/SMSO) composite day–night photocatalyst is synthesized, using a model methyl orange (MO) substrate, and the impacts of trace P doping and the SMSO composite on the activity of the photocatalyst in MO degradation is investigated; Its antibacterial effect against Escherichia coli and Staphylococcus aureus on ceramic surfaces is further examined. The morphology, structure, and composition of the photocatalyst are characterized by SEM, TEM, XRD, FT-IR, and UV–vis DRS. Finally, the photocatalytic mechanism is elucidated through active species capture experiments and ESR testing. P doping and the SMSO heterojunction structure reduce the width of the forbidden band of g-C3N4 and broaden its visible-light-response range. Moreover, SMSO acts as a light source to realize long-lasting photocatalytic performance of the composite, even in the dark. The photocatalytic process produces •O2-, 1O2, and h+ active species, with •O2- and 1O2 playing the dominant role—instead of •OH as previously thought.

Adsorption coupling photocatalytic removal of gaseous n-hexane by phosphorus-doped g-C3N4/TiO2/Zn(OAc)2-ACF composites.

VOCs emission reduction in the petroleum and petrochemical industry is a hot and difficult topic at present. The single method may not be able to meet the actual treatment status. Therefore, the adsorption coupled photocatalytic degradation technology was used to remove VOCs. Phosphorus-doped carbon nitride (PCN) and PCN/TiO2 were prepared by hydrothermal synthesis and sol-gel method, and then PCN/TiO2/Zn(OAc)2-ACF composites were prepared by ultrasonic impregnation on zinc acetate modified activated carbon fibers (Zn(OAc)2-ACF). The removal efficiency of n-hexane by composite materials was explored in a self-made reactor, and the factors affecting removal efficiency, removal mechanism, and possible ways of degradation were investigated. The results showed that under the optimum reaction conditions (initial concentration of n-hexane 200mg/m3, space velocity 1000h-1, light intensity 24W, mass fraction of doped PCN 6%, loading twice, calcination temperature 450°C), PCN/TiO2/Zn(OAc)2-ACF composite has the highest removal efficiency of n-hexane (90.2%). The adsorption capacity of the composites after doping the P element was 215.3mg/g, which did not enhance the adsorption performance compared with that before doping, but the removal rate of n-hexane was higher. This showed that doping P element was helpful to enhance the photocatalytic activity of the composites.

Band gap narrowing ternary phosphorus-doped g-C3N4/Fe0@expanded graphite carbon layer hybrid composite for effective degradation of tetracycline via multiply synergistic mechanisms

The wide band gap of g-C3N4 and severe aggregation of Fe0 adequately limit their applications. To address these two critical issues, novel ternary phosphorus-doped g-C3N4/Fe0 @expanded graphite carbon layer (P-CN/Fe0 @EGC) photocatalyst with extremely narrow band gap and significantly enhanced catalytic activity was in-situ synthesized. P-CN/Fe0 @EGC hybrid composite exhibited excellent photodegradation performance of tetracycline (TC) removal, which is 5.18 and 1.92 times higher than that of pristine g-C3N4 and Fe0, respectively. Enhancement in photocatalytic activity is evaluated via photoluminescence (PL), UV–vis DRS, XRD and electron spin resonance (ESR). A reasonable catalytic mechanism of P-CN/Fe0 @EGC is proposed. The multiply synergistic mechanisms of phosphorus-doped g-C3N4 (P-CN), Fe0 and expanded graphite carbon layer (EGC), as well as the strong reducibility of Fe0 were accounted for the expanded visible light absorption range. The even dispersion of Fe0 on porous and worm-like structured P-CN/EGC effectively and successfully avoided the decline in photocatalytic activity caused by aggregation of Fe0 nanoparticles. Compared with g-C3N4, the band gap of phosphorus-doped g-C3N4 was narrowed from 2.79 to 2.60 eV. It is worth noting that Fe0 plays an important role in accelerating electron transfer speed and efficiency between P-CN and EGC. The·O2− and h+ were the dominant active substances for TC degradation. Moreover, P-CN/Fe0 @EGC catalyst could be used repeatedly for at least 7 cycles with high TC removal efficiency. This study may pave a new way on designing high efficient ternary hybrid photocatalyst for antibiotic degradation.

High-efficiency ultrathin porous phosphorus-doped graphitic carbon nitride nanosheet photocatalyst for energy production and environmental remediation

Herein, we designed and constructed an ultrathin porous phosphorus-doped g-C3N4 nanosheet (PCN) bifunctional photocatalytic system for efficient production of H2O2 and degradation of non-steroidal anti-inflammatory drugs in aqueous environment. The phosphorus atoms introduced in g-C3N4 significantly improved the utilization of light, enhanced the adsorption capacity for O2, and inhibited the recombination of photogenerated carriers, thereby boosting the photocatalytic performance. Consequently, the optimized PCN photocatalyst produced 285.34 μM of H2O2 under blue LED light irradiation, which was 3.41 times that of pristine g-C3N4, and its degradation rate constant for diclofenac (0.1248 min−1) was 46.22 times that of the g-C3N4. Density functional theory (DFT) calculations suggested that phosphorus doping modulated the local electronic structure of g-C3N4, which improved the electron-hole separation and promoted the O2 reduction reaction. This work comprehensively reveals the mechanisms of phosphorus doping on g-C3N4, while offering a promising strategy for addressing current energy demands and environmental remediation concerns.

Synthesis and characterization of P-doped g-C3N4 nanosheet hybridized ZnS nanospheres with enhanced visible-light photocatalytic activity

Phosphorus-doped g-C3N4/ZnS (PCN/ZnS) composite photocatalyst was prepared by element doping and structuring heterojunction by solvothermal methods. The heterojunction composite was characterized by XRD, SEM/TEM, XPS and UV–vis DRS. The photocatalytic properties of PCN, ZnS and PCN/ZnS were studied by photodegradation of tetracycline (TC) with visible light irradiation. The 15%PCN/ZnS showed the highest photocatalytic degradation performance of TC with the reaction rate constant of 0.0529 min−1, which was 40.7 times of ZnS and 6.3 times of PCN. Superoxide radicals and holes played a major role in the photocatalytic degradation process, but not hydroxyl radicals. Besides, according to the conduction and entrainment positions of PCN and ZnS, they form a type II heterojunction structure, which could extend the range of light response, enhance the charges transfer and efficient separation. In general, the design and synthesis of PCN/ZnS provide a new way to photodegrade pharmaceutical wastewater with enhanced photocatalytic properties.

Designing hierarchical ternary structure based on NiAl LDH anchored phosphorus-doped g-C3N4 dotted with Fe3O4 nanoparticles towards improving the fire safety of thermoplastic polyurethane

High fire hazard of generating a great deal of heat and toxic volatiles has been deemed as notorious issue of thermoplastic polyurethane (TPU), severely impeding its practical usage. Hence, a hierarchical ternary structure (FNPCN) based on NiAl LDH anchored phosphorus-doped g-C3N4 dotted with Fe3O4 nanoparticles is rationally designed as flame retarded additive for TPU. Specifically, by adding 1.0 wt% FNPCN, the obvious reductions of 30.9% and 21.8% in peak heat release rate and total heat release are obtained, suggesting the suppressed heat release. Meanwhile, a marked decrease of 31.9% in peak smoke production rate is discovered, implying the reduced fire toxicity. Moreover, the direct evidence for hindered releases of toxic CO and HCN gases is provided by TG-IR spectra. These results jointly corroborate the efficacy of FNPCN in impairing the fire hazard of TPU, originating from its physical barrier and chemical catalyst characters. This work may shed a light on the designing of hierarchical ternary structure, optimizing their prospects in polymer-matrix composite and other areas.

Enhancing electron density of bulk g-C3N4 through phosphorus doping for promoting photocatalytic hydrogen evolution reaction

Graphite-phase carbon nitride (g-C3N4) has attracted extensive attention due the ubiquity of the raw materials, low price, and excellent visible light photocatalytic hydrogen evolution reaction (HER) activity. Bulk g-C3N4 is more advantageous for industrial production and application compared with g-C3N4 nanostructures such as nanosheets. Polyphosphate cyanogen was used herein as a phosphorus source to prepare phosphorus-doped bulk g-C3N4 with a coral-like hierarchical structure. This structure affords more extensive contact between the photocatalyst and reaction medium, and is thus beneficial for the photocatalytic hydrogen evolution reaction (HER). Density functional theory calculations showed that phosphorus-doping in bulk g-C3N4 can increase the electron density, thereby enhancing the separation and transfer of photon-generated carriers. The rate of the photocatalytic HER is thus promoted due to the faster separation and transfer of photoexcited electron-hole pairs. Bulk g-C3N4 doped with 20% phosphorous afforded a photocatalytic hydrogen production rate of 2.96 mmol g−1h−1, which is ∼ 3 times higher than that of the original bulk g-C3N4 sample with 1% Pt loading (1.01 mmol g−1h−1) under visible light. This study may inspire the further development of phosphorus-doped g-C3N4 for harvesting and converting solar energy to hydrogen energy.