Sulfur-doped Carbon Nitride Research Articles

Dual-functional high-crystalline 3D core-shell hexagonal tubular sulfur-doped carbon nitride for enhanced photocatalytic H2 production and simultaneously pollutants degradation

Dual-functional high-crystalline 3D core-shell hexagonal tubular sulfur-doped carbon nitride for enhanced photocatalytic H2 production and simultaneously pollutants degradation

Enhanced photocatalytic hydrogen evolution using dual templates of sulfur-doped carbon nitride

The band structure of semiconducting photocatalysts plays a crucial role in determining their charge carrier transport characteristics and photocatalytic activity. In this work, a simple method to modulate the band structures of carbon nitride by infusing dopants and porous materials is experimentally demonstrated. A combination of trithiocyanuric acid and ammonium chloride to calcinate in an air environment, sulfur dopants and a significant amount of porosity are infused into carbon nitride concurrently. The sulfur-doped and porous carbon nitride material shows remarkable performance in photocatalytic hydrogen production, achieving a maximum hydrogen evolution rate of 4516.84 μmol g−1 h−1. Furthermore, infusion of sulfur dopants and abundant porous into carbon nitride allows for substantial and continuous tuning of the conduction and valence band positions. The band structures modulation enhanced the optical absorption in visible light region, making it suitable for efficient solar energy conversion. The findings of this work are feasible to pave a foundation for future clean energy technology.

Application of multilevel immobilized carbon nanotube/sulfur doped carbon nitride composite photocatalytic coating for Cr6+(aq.) reduction

The difficulty in immobilizing carbon nitride (GCN), and the decrease in sorption capacity and photocatalytic performance after immobilization process have become two major bottlenecks limiting the practical application of carbon nitride in photocatalysis field. Herein, sulfur doped carbon nitride and carbon nanotube composite photocatalysts (CNT/SCN) with high sorption, light harvesting capacity, and reduction efficiency was synthesized by two-step solvothermal method. Furthermore, CNT/SCN composite photocatalytic coating with porous three-dimensional surface morphology was prepared using double liquid phase high speeding spray-deposition method. The coverage rate of CNT/SCN coating was calculated to be 55 %, which was 1.57 times higher than that of GCN coating. The introduction of carbon nanotube (CNT) significantly improved the sorption capacity of photocatalytic coating for hexavalent chromium (Cr6+(aq.)). The reduction efficiency of the composite coating towards Cr6+(aq.) under flowing water conditions was further investigated. The CNT/SCN coating exhibited a high removal efficiency of 84.7 % for Cr6+(aq.) (500 mL, 10 mgL−1) within 8 h, which was 29 times than that of GCN coating. The reduction efficiency of CNT/SCN photocatalytic coating remained above 75 % after three cycles of testing. This research provides theoretical basis and data support for the immobilization application of photocatalysts.

Novel defect-transit dual Z-scheme heterojunction: Sulfur-doped carbon nitride nanotubes loaded with bismuth oxide and bismuth sulfide for efficient photocatalytic amine oxidation

The rational design of Z-scheme heterojunction hybrid photocatalysts is considered a promising way to achieve high photocatalytic activity. In this study, a dual Z-scheme heterojunction with bismuth sulfide (Bi2S3) nanorods and bismuth oxide (Bi2O3) nanoparticles anchored Sulfur-doped carbon nitride (S-CN) nanotubes (Bi2S3/S-CN/Bi2O3) is designed and fabricated through the ordinal metal ion adsorption, pyrolysis, and sulfidation processes using supramolecular rods as precursor. Compared with pristine Bi2S3, Bi2O3, and CN, the dual Z-scheme tube-shaped Bi2S3/S-CN/Bi2O3 catalyst exhibited a significantly improved photocatalytic activity in amine oxidation. The optimized Bi2S3/S-CN/Bi2O3 nanostructure exhibits a 97.6 % benzylamine conversion and 99.4 % imine selectivity within 4 h under simulated solar light irradiation. The excellent activity of Bi2S3/S-CN/Bi2O3 nanotubes can be attributed to the characteristic hollow defect band structure and efficient charge separation and transfer achieved by the dual Z-scheme charge transfer mechanism, which was systematically studied using electron spin resonance spectroscopy, Kelvin probe force microscope, and other techniques. The optimized dual Z-scheme heterojunction hybrid photocatalyst maintains the high oxidizing ability of Bi2S3 and Bi2O3 and the excellent reducing ability of CN, thereby significantly enhancing the photocatalytic activity. This research provides a facile and feasible synthesis strategy for designing dual Z-scheme heterojunctions with defect band structure to improve the photocatalytic activity.

Bidirectional heterojunctions photocatalyst engineered with separated dual reduction sites for hydrogen evolution

Photocatalytic technology is identified as one of the most clean and sustainable routes for hydrogen generation. Nonetheless, inadequate photoinduced carrier separation limits photocatalytic performance. Rationally designing bidirectional heterojunctions that leverage single/two-photon co-excitation pathways and dual reduction sites, thereby inhibiting recombination of the photoinduced carriers and exposing active sites to increase photocatalytic activity. This study proposes bidirectional heterojunctions consisting of 0D carbon dots (CDs) and nickel phthalocyanines co-modified sulfur-doped multivesicular carbon nitride tubes (denoted as 7CDs/SMVCTs/Ni0.5 %). The as-prepared photocatalyst displays a remarkable yield of 16,363.62 μmol g−1 h−1, with a rate 23.2 times that of pristine carbon nitride (denoted as PCN, 704.23 μmol g−1 h−1). The improvement of photocatalytic performance is attributed to the efficient separation and transportation of photoexcited electron-hole pairs induced by the coexistence of single/two-photon excitation pathways and dual reduction sites. The efficient combination of lateral and vertical heterostructures plays an essential role in the photocatalytic process and is exhaustively studied using catalyst rational design and modification technology.

Tailoring sulfur-doped and nitrogen-defective carbon nitride nanosheets for efficient photo-controlled radical polymerizations

Tailoring sulfur-doped and nitrogen-defective carbon nitride nanosheets for efficient photo-controlled radical polymerizations

A novel, low-cost, and efficient separation strategy based on S-doped C3N4 for the analysis of PCDD/Fs and dioxin-like PCBs

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) are widespread and highly toxic persistent organic pollutants with similar chemical structure. The popular process for the separation of PCDD/Fs and dl-PCBs in one sample often relies on imported and expensive activated carbon, giving rise to an urgent need of inexpensive and efficient separation method. Herein, a novel, simple, and low-cost separation strategy based on sulfur-doped carbon nitride (S-C3N4) is reported. The S-C3N4 material was synthesized through simple thermal annealing with precursor of thiocyanuric acid. After recovery experiments, the optimal addition ratio of S-C3N4 was determined to be 40% mixed with silica gel. The recoveries for PCDD/Fs and dl-PCBs congeners are 32% - 105% and 60% - 70% respectively, which not only meets USEPA and Chinese standards but also shows comparable performance to activated carbon. Moreover, the proposed S-C3N4 strategy exhibits excellent performance for the analysis of PCDD/Fs and dl-PCBs in real complex samples (sediment and fish liver) in terms of detected concentrations and toxic equivalents. Overall, this study puts forward a new and low-cost avenue for the separation of PCDD/Fs and dl-PCBs, which is of remarkable meaning for motivating the development of detection techniques and domestic equipment for dioxins and other pollutants in the environment.

Construction and modularization of porous sulfur-doped carbon nitride nanotubes with excellent photocatalytic activity and potential engineering application value

In this paper, we successfully fabricate a porous sulfur-doped carbon nitride nanotubes (p-C3N4-xSx NTs) for the first time with melamine (C3H6N6), trithiocyanuric acid (C3H3N3S3), and sodium chloride (NaCl) as precursors by a simple thermal polymerization strategy. The doping of sulfur element and the construction of porous nanotube microstructure can effectively improve the transmission efficiency of photogenerated electrons in p-C3N4-xSx NTs. Therefore, the as-prepared p-C3N4-xSx NTs shows excellent visible-light photocatalytic performance in the photocatalytic reactions of hydrogen peroxide (H2O2) production and Rhodamine B (RhB) degradation. The proposed micro-path indicates that C3H3N3S3 acts as both sulfur source and pore-forming agent, while NaCl acts as the structural guide agent to form tubular nanostructures during p-C3N4-xSx NTs preparation. In addition, we also successfully prepare modular p-C3N4-xSx NTs@SA with potential engineering application value through a simple sol-gel strategy by using sodium alginate (SA) as a precursor in order to solve the difficult problem of separation and recovery of powder photocatalysts.

Sulfur-doped carbon nitride functionalized PVDF membrane with S⋯H[sbnd]N bridge induced fast carrier transfer for bifunctional H2O2 and H2 production

The utilization of green and pollution-free solar energy for photocatalytic reduction of oxygen (O2) to hydrogen peroxide (H2O2) is a highly desirable technology. In this work, sulfur (S)-doped graphitic carbon nitride (SCN) nanosheets were prepared by co-condensation of carbon nitride with thioacetamide as a sulfur source. The substitution of sp2 hybridized N atoms by S atoms created S⋯HN bridges through weak hydrogen bonds, promoting fast carrier separation and transfer. Moreover, the S-doping could effectively reduce the band gap by approximately 0.6 eV, and thereby expand photo-responsive region of SCN-based photocatalysts up to 700 nm. To gain the practicability and retrievability of prepared photocatalysts, we developed SCN-based nanomaterials functionalized polyvinylidene fluoride (PVDF) membranes for H2O2 production and H2 evolution. The optimized photocatalytic efficiency of SCN-3 reached 1491 μmol L–1 h−1 of H2O2 generation and 16.3 mmol g–1 h−1 of H2 evolution under monochromatic LED light irradiation, nearly 2–5 times higher than the state-of-art metal-free photocatalysts. These findings offer new insights into the doping regulated nanocatalysts functionalized membranes to achieve high performance in practical applications.

Revealing the synergistic effect between radical and non-radical species of sulfur-doped carbon nitride for ciprofloxacin removal: Based on density functional theory study

The distinct characteristics of active species produced during the photocatalytic reaction can result in alterations in the degradation routes of organic pollutants with diverse chemical structures. The relationship between the active species and degradation pathways of organic pollutants lacks a direct experimental or characterization method, so in-depth research is still needed to understand the details of their interactions. In this study, sulfur-doped bulk carbon nitride (SBCN) was prepared based on bulk carbon nitride (BCN), and the process of S-doping enhancing the production of O21 was revealed. Through the degradation experiment, the degradation rate of CIP by SBCN reached 91 %, which was higher than that of BCN (66 %). The increase of degradation rate was mainly attributed to the increase of O21. Through the density functional theory (DFT) calculation of CIP and its degradation intermediate, due to the preferential oxidation of CIP by O21, O21 changes the initial degradation direction of CIP, releasing more attack sites for ˙O2−, thereby achieving more efficient degradation of CIP through the synergy of O21 and ˙O2−. In this study, the attack preferences of the active species and their synergistic promotion provide important insights for the efficient photocatalytic degradation of organic pollutants.

Visible light driven degradation of BPA and LDPE microplastic films using GO/SCN nanocomposite.

A sonication assisted method was employed to prepare a graphene oxide (GO)/sulfur doped carbon nitride (SCN) nanocomposite, demonstrating enhanced photocatalytic activity compared to GO and SCN. Extensive characterization confirmed the improved properties of the nanocomposite. X-ray Diffraction (XRD) results indicated that the SCN lattice remained intact upon GO addition while Fourier-transform infrared spectroscopy (FTIR) revealed chemical interaction between GO and SCN. X-ray photoelectron spectroscopy (XPS) confirmed sulfur incorporation into the graphitic carbon nitride (g-C3N4) lattice. Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) highlighted the distinct morphological features of GO, SCN, and GO/SCN nanocomposites, with SCN showing flat, thin nanosheets and GO displaying flake-like layers, both contributing to a high surface area and mechanical strength. In the GO/SCN nanocomposite, these structures were intermixed, enhancing surface area, mechanical stability, and electron mobility, which contributed to the improved catalytic performance. Ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) showed a reduction in band gap energy from 2.62 eV for SCN to 2.52 eV for the GO/SCN composite, leading to enhanced visible light absorption. Under visible light irradiation, low density polyethene (LDPE) films experienced significant degradation, evidenced by a 21% weight loss after 10 days, supported by SEM analyses showcasing surface changes on the LDPE films. The degradation was further confirmed by an increase in the carbonyl index (C.I.) from 0.37 to 1.24, measured through FTIR analyses, indicating oxidation corroborating the degradation process. Furthermore, BPA degradation reached 89.5% within 60 minutes under visible light irradiation. Radical trapping experiments confirmed hydroxyl radicals (˙OH) as the active oxygen species involved in the degradation of BPA.

Rod-shaped aggregates of sulfur-doped carbon nitride nanosheets for enhanced photocatalytic hydrogen evolution

Rod-shaped aggregates of sulfur-doped carbon nitride nanosheets for enhanced photocatalytic hydrogen evolution

Sulfur-doped carbon nitride with carbon vacancies: Enhanced photocatalytic activity for degradation of tetracycline hydrochloride

This study presents a novel approach for the synthesis of sulfur-doped g-C3N4 with carbon vacancies using thioacetamide (TAA) as the sulfur source, combined with melamine under a self-generated ammonia environment in a closed crucible. The morphological properties of the modified catalyst were characterized, revealing that carbon vacancies and sulfur-doped decreased the catalyst's forbidden bandwidth, increased surface area, enhanced absorption of visible light, and improved the separation efficiency of photogenerated carriers. The modified carbon nitride demonstrates a remarkable degradation efficiency for tetracycline hydrochloride, achieving approximately 90 % degradation after 60 min of reaction time under a 5 W LED lamp, which is 3.4 times higher than that of pure carbon nitride. Furthermore, the toxicity analysis of the solution after photocatalyst degradation was evaluated with active E. coli, and no significant effect was observed. Overall, this study provides a novel approach for the structural modification of g-C3N4, resulting in enhanced photocatalytic activity.

The purification performance of S doped g-C3N4 photocatalyst with outstanding reduction efficiency over Cr(VI) under the actual underwater transmission light

Cr(VI) existed in the industrial wastewater which has high biological toxicity has become one of the main pollution sources at present, and it is also difficult to remove from the wastewater because of its chemical stability. In this work, a raspberry-like sulfur doped carbon nitride photocatalyst (SCNx) with significant high reduction performance over Cr(VI) was prepared by solvothermal process. The BET data showed that the specific surface area of SCN4 was 3.75 times that of g-C3N4. Meanwhile, sulfur doping successfully reduce the band gap, which significantly improve the effective photoelectron density on the surface of the material, thus enhance its reduction ability. On this basis, the reduction activity of the SCNx to Cr(VI) in actual underwater environment was further investigated. Results show that SCNx still has good removal performance under weak light intensity and weak UV conditions. At 20 cm depth where ultraviolet spectral is attenuated 86.2%, the removal rate of SCN4 over Cr(VI) can still reach 58.1%. This research demonstrated that through S-doping and morphology control modification, carbon nitride can remain high photoreaction activity in the underwater weak light and weak UV environment, thus realize the efficient reduction treatment of Cr(VI). The research demonstrated the feasibility of heavy metal water treatment, and indicate a possible direction for the future practical application of heavy metal water purification.

Tailoring a sulfur doped carbon nitride skeleton to enhance the photocatalytic hydrogen evolution activity

A sulfur doped carbon nitride skeleton with enhanced photocatalytic hydrogen evolution activity is tailored via thermal-melting followed by thermal-copolymerization of urea and dithizone.

Self-supporting porous S-doped graphitic carbon nitride as a multifunctional support of Au catalyst: Application to highly sensitive and selective determination of arsenic (III) in a wide range of pH

To investigate heteroatom-doped carbon nitride (C3N4) materials as supports, Au nanoparticles anchored on sulfur-doped carbon nitride nanosheets (AuNPs@SCNN) was prepared and used as a catalyst for arsenic electroreduction. Novel SCNN was synthesized for the first time via a simple thermally induced copolymerization route using ammonium persulfate (APS) as a low-cost sulfur source. Thereafter, the SCNN was used to integrate with AuNPs for the benefit of enhancing the quality of assembly and interface between SCNN and AuNPs and improving the catalytic activity of the AuNPs@SCNN nanocatalyst. This optimized assembly was characterized by different techniques, morphologically favorable heterojunction formation between SCNN and AuNPs. More importantly, it was confirmed that the addition of APS during the polymerization of urea not only afforded a significant morphological change from a layered material to a porous structure with many in-plane holes, but also resulted in a higher yield than urea. The electrocatalytic reduction of arsenic was considered at a glassy carbon electrode modified by the composite (AuNPs@SCNN/GCE), which exhibited enhanced electrochemical responses in a wide range of pH conditions with minimal interference of Cu. More distinctly, this robust and repeatable detection method exhibits a linearity range of 0.2–30.0 ppb and a detection limit of 0.07 ppb. The successful determination of arsenic concentration in real water samples also underpins its practical applications in the real world. This promotes innovative design for the synthesis of novel functional nanocomposites.

CuCo and sulfur doped carbon nitride composite as an effective Fenton-like catalyst in a wide pH range.

The heterogeneous Fenton-like reaction, as an advanced oxidation process, is widely recognized attributed to its recyclability, wide pH response range, easy solid-liquid separation, and non-production of iron sludge. Recently, the bimetallic catalysts have attracted intense attention due to their high catalytic performance and excellent stability over a wide pH range. In this article, CuCo/SCN bimetallic catalyst was prepared by pyrolysis method with sulfur doped carbon nitride (SCN) as the carrier. Under the conditions of pH = 7, catalyst dosage of 0.8 g/L, and concentration of H2O2 of 15 mM, 20 mg/L of methyl orange (MO) can be completely removed within 1 h. With the synergistic action between bimetals and sulfur doped carbon nitride, the CuCO/SCN involved Fenton-like system exhibited excellent catalytic degradation efficiency and strong stability for MO in neutral and weak alkaline conditions. The EPR characterization proved that OH and O2 − were the main active components. Furthermore, CuCo/SCN involved Fenton-like system has good adaptability. Bimetallic CuCo/SCN catalyst has great application potential in the degradation of environmental pollutants.

Sulfur-doped graphitic carbon nitride nanosheets as a sensitive fluorescent probe for detecting environmental and intracellular Ag+

Silver is widely used in medical materials, photography, electronics and other industries as a precious metal. The large-scale industrial production of silver-containing products and liquid waste emissions aggravate the environmental pollution. Silver ion is one of the most toxic metal ions, causing pollution to the environment and damage to public health. Therefore, the efficient and sensitive detection of Ag+ in the water environment is extremely important. Sulfur-doped carbon nitride nanosheets (SCN Ns) were prepared by melamine and thiourea via high-temperature calcination. The morphology, chemical composition and surface functional groups of the SCN Ns were characterized by SEM, TEM, XRD, XPS, and FT-IR. The fluorescence of SCN Ns was gradually quenched as the Ag+ concentration increased. The detection limit for Ag+ was as low as 0.28 nM. The quenching mechanism mainly is attributed to static quenching. In this paper, SCN Ns were used as the fluorescent probe for detecting Ag+. SCN Ns have successfully detected Ag+ in different environmental aqueous samples and cells. Finally, SCN Ns were further applied to the visual quantitative detection of intracellular Ag+.

Enhanced photocatalytic degradation and H2 evolution performance of N CDs/S-C3N4 S-scheme heterojunction constructed by π-π conjugate self-assembly

• Novel 0D/2D N CDs/S-C 3 N 4 S-scheme heterojunction was prepared by a simple solvent evaporation induced self-assembly method. • FT-IR and HRTEM confirmed that N CDs were supported on S-C 3 N 4 through π-π conjugate interaction. • N CDs/S-C 3 N 4 demonstrated superior photocatalytic performance in degrading organic pollutants and hydrogen evolution. • The enhanced photocatalytic activity was attributed to the formation of S-scheme heterojunction with high redox potentials. Constructing heterojunction between two semiconductors with matched energy band structure is an effective modification method to obtain excellent photocatalysts. The experimental scheme adopts a simple solvent method to self-assemble nitrogen doped carbon dots (N CDs) on the surface of sulfur doped carbon nitride (S-C 3 N 4 ) semiconductor through π-π conjugate interaction. Based on this, a novel 0D/2D S-scheme heterojunction N CDs/S-C 3 N 4 hybrid was successfully prepared. The degradation kinetic constants of N CDs/S-C 3 N 4 for rhodamine B (RhB) and p-nitrophenol (PNP) reached 0.23522 and 0.01342 min −1 , respectively, which were 2.72 and 2.65 times that of S-C 3 N 4 . The highest photocatalytic hydrogen evolution rate was observed under the simulated sunlight irradiation, which was 2.30 times that of S-C 3 N 4 . The improvement of photocatalytic performance was mainly based on the formation of the S-scheme heterojunction between S-C 3 N 4 and N CDs. The effects of internal electric field, π-π conjugate interaction and band bending promoted the photogenerated h + and e − with low redox ability to recombine and retained the beneficial h + and e − with strong redox ability, which contributed to the production of more active species of h + and • O 2 − , therefore the photocatalytic degradation and hydrogen evolution performance were significantly enhanced.

Surface engineering of 3D spinel Zn3V2O8 wrapped on sulfur doped graphitic nitride composites: Investigation on the dual role of electrocatalyst for simultaneous detection of antibiotic drugs in biological fluids

Sensitive detection of antibiotics is one of the crucial research areas at present. The present work describes the simple deep eutectic solvent based hydrothermal methods for the synthesis of 3D metal vanadate's; T3V2O8 (T = Cu, Ni and Zn). Further, these 3D T3V2O8 have been anchored with sulfur doped carbon nitride (SGN). The morphological characterization confirms the formation of rhombus, rice and flower like structures of CVO, NVO and ZVO, respectively. All the three nanocomposites have been used to modify laser-induced graphene electrodes (LGE) and been evaluated for the detection of two antibiotics; nitrofurantoin (NFT) and chloramphenicol (CAP). The electrochemical performance of antibiotics has been studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques. Among three composites ZVO/SGN showed enhanced selectivity and sensitivity compared to CVO/SGN and NVO/SGN. Using DPV method, the sensitivity of the ZVO/SGN/LGE sensor achieved for the detection of CAP and NFT is 55.71 μA μM−1 cm−2 and 23.06 μA μM−1 cm−2 respectively. Using this ZVO/SGN nanomaterial-enhanced multiplex electrochemical sensing system, simultaneous detection of CAP and NFT was realized with a limit of detection of 1.5 nM and 2.4 nM, respectively. To validate the use of the sensor in real sample applications, detection experiments were performed in bovine serum and urine. The ZVO/SGN modified LGE shows enhanced sensitivity as well as selectivity for the simultaneous detection of NFT and CAP.