S-doped g-C3N4 Research Articles

Ag2Se nanoparticles anchored on S-g-C3N4 nanosheets towards efficient photocatalytic tetracycline hydrochloride removal and H2 generation

To improve the stability of Ag based co-catalysts and to increase the photocatalytic performance of graphitic carbon nitride (g-C3N4), Ag2Se nanoparticles were grown onto superior thin sulfur-doped g-C3N4 nanosheets which was fabricated via two-step thermal polymerization at high temperature. Ultrathin S-doped g-C3N4 nanosheets were prepared via two-step thermal polymerization using melamine and thiourea. The ratios of Ag2Se were adjusted to fabricate a series of Ag2Se/S-g-C3N4 (Ag2Se/SCN) composite samples by controlled solvothermal synthesis. S-doping plays an important role in mono-dispersion of Ag2Se nanoparticles on S-g-C3N4 nanosheets because of the control of growth sites. The photocatalytic removal of tetracycline hydrochloride test indicates that sample Ag2Se/SCN-3 with Ag2Se loading of 3 % reveals the best removal effect, in which tetracycline hydrochloride of 60 % is removed within 60 min. Photocatalytic hydrogen generation test results without co-catalyst addition demonstrate that sample Ag2Se/SCN-3 exhibits the best H2 evolution rate of 2116.35 μmol·g−1·h−1, which is 3.8 times of that of pure carbon nitride. The photocatalytic mechanism tests suggest that Schottky heterojunctions are formed in the Ag2Se/S-g-C3N4 composites. The formation of Schottky heterojunctions improved the separation efficiency of photogenerated charge carriers. The incorporation of Ag2Se nanoparticles (as the co-catalyst) on S-g-C3N4 nanosheets is the key for drastically improving the photocatalytic performance and eliminating the use of Pt co-catalyst during the photocatalytic processes.

In Situ Construction of Hollow Coral-Like Porous S-Doped g-C3N4/ZnIn2S4 S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution.

The rational design of visible-light-responsive catalysts is crucial for converting solar energy into hydrogen energy to promote sustainable energy development. In this work, a C─S─C bond is introduced into g-C3N4 (CN) through S doping. With the help of the flexible C─S─C bond under specific stimuli, a hollow coral-like porous structure of S-doped g-C3N4 (S-CN) is synthesized for the first time. And an S-doped g-C3N4/ZnIn2S4 (S-CN/ZIS) heterojunction catalyst is in situ synthesized based on S-CN. S0.5-CN/ZIS exhibits excellent photocatalytic hydrogen evolution (PHE) efficiency (19.25mmol g-1 h-1), which is 2.7 times higher than that of the g-C3N4/ZnIn2S4 (CN/ZIS) catalyst (8.46mmol g-1 h-1), with a high surface quantum efficiency (AQE) of 34.43% at 420nm. Experiments and theoretical calculations demonstrate that the excellent photocatalytic performance is attributed to the larger specific surface area and porosity, enhanced interfacial electric field (IEF) effect, and appropriate hydrogen adsorption Gibbs free energy (ΔGH*). The synergistic effect of S doping and S-scheme heterojunction contributes to the above advancement. This study provides new insights and theoretical basis for the design of CN-based photocatalysts.

BiVO4/sulfur-doped g-C3N4 nanocomposite as photocatalyst for degradation of ciprofloxacin under visible light irradiation

In recent years, the use of antibiotics has greatly increased, which has caused environmental pollution. We offer a photocatalyst based on BiVO4/sulfur-doped g-C3N4 nanocomposite, which was made by a one-step thermal condensation method from thiourea and bismuth vanadate to degradate ciprofloxacin (CIP). The BiVO4/sulfur-doped g-C3N4 photocatalyst was analyzed by certain techniques including XRD, FTIR, BET, FESEM, EDX, TEM, DRS, photoluminesence, and Mott-Schottky to determine various physicochemical properties. The photocatalytic degradation of CIP, as a model pollutant, under visible LED light irradiation was tested to investigate the catalytic performance of nanocomposite. Response Surface Methodology (RSM) was employed to optimize operational parameters, including photocatalyst dosage (50–150 mg), CIP concentration (10–30 mg/L), initial pH of the solution (3–11), and irradiation time (12–120 min). The BiVO4/sulfur-doped g-C3N4 nanocomposite, with a narrow bandgap of 2.15 eV, exhibited exceptional photocatalytic performance in degrading CIP. The optimal conditions for CIP removal were photocatalyst dosage of 120.9 mg, CIP concentration of 10 mg/L, and initial solution pH of 3, resulting in 93.5 % removal efficiency after 105 min of irradiation. The photocatalytic degradation kinetics of CIP followed a pseudo-first-order model with a rate constant (K) of −0.0221 L/min, indicating rapid degradation process. The photocatalyst maintained excellent performance after 5 reuses, with only a 3 % reduction in efficiency. XRD analysis confirmed the structural stability of the nanocomposite after reuse.

Exploiting the efficiency of narrow band gap S-doped g-C3N4/Expanded Perlite/Red Ocher nanocomposite for high-level eliminating halogenated dye in Cool‐White‐SMD/H2O2 system

Hitherto, constructing prominent visible-light-driven g-C3N4/soil composites still suffers from several intricacies, including low specific surface area, inadequate charge separation, and a high band gap energy (Eg >2.7 eV). To address these drawbacks, sulfur atoms were introduced into g-C3N4 (S-doped g-C3N4 or SCN); thereby, Red Ocher (RO) and Expanded Perlite (EP) were grafted to SCN, which the engineered SCN/10EP/20RO nanocomposite divulged a higher specific surface area, further light-harvesting capability, narrower Eg, prolonged charge recombination process, lower the charge transfer resistance, and higher photocurrent density than bulk g-C3N4 (CN). Additionally, the formed S-scheme charge migration mechanism and the hole-trapping role of the hydroxyl functional groups synergistically engendered robust visible-light-driven catalytic performances under visible-light exposure. By enabling the heterogeneous photo-Fenton-like process, the Methylene Blue removal efficiency (MBRE) and the Total Organic Carbon (TOC) decontamination promptly elevated to 99.6% and 87.7% within 90 min under Cool-White-SMD/H2O2 condition, respectively. Manifestly, the kinetic reaction rate of the photo-Fenton-like process was 7.5 times higher than the primary photocatalysis, showcasing HO•had a determining role towards decent decomposing MB. After overviewing, our detailed findings straightforwardly corroborated that SCN/10EP/20RO nanocomposite would be an efficient, long-lasting, and green photocatalyst for eradicating halogenated organic pollution.

Interface-engineering derived WS2/S-g-C3N4 nanosheet Z-scheme heterostructures towards enhanced photocatalytic redox and H2O2 generation

The growth of WS2 on S-doped graphic carbon nitrides (g-C3N4) was controlled to utilize horizontal implanting and get fine interfacial characteristic. Superior thin S-doped g-C3N4 nanosheets were fabricated via a two-step thermal polymerization at high temperature. Subsequent solvothermal procedure was used to create WS2/S-g-C3N4 (WS2/SCN) photocatalytic heterojunctions with optimized component ratios, in which doped S components in g-C3N4 play an important role for the horizontal growth and homogeneous distribution of WS2 nanosheets. Z-scheme charge transfer mechanism was proposed according to various characterizations. Photocatalytic rhodamine B (Rh B) degradation test indicated that WS2/SCN 15 % (sample WS2/SCN-3) revealed the best performance, in which Rh B of 92.8 % was photocatalytic oxidated with 20 min. Photocatalytic hydrogen generation experiments indicated that sample WS2/SCN-3 exhibited a H2 generation rate of 1380 μmol·g−1∙h−1, which was 3.7 times of that of S-g-C3N4 nanosheets. These WS2/S-g-C3N4 heterojunctions also exhibited excellent performance for photocatalytic H2O2 evolution. Sample WS2/SCN-3 exhibited a H2O2 generation rate of 5216 μmol·g−1·h−1 which was 6.4 times that of S-g-C3N4 sample. This excellent photocatalytic activity is scribed to WS2/S-g-C3N4 layered heterojunctions with well-developed interface characteristic. The result supplied an efficient approach for the preparation of photocatalysts.

S-doped g-C3N4 on Co/Ni metal-organic framework as efficient bifunctional electrocatalyst for in-situ hydrogen production from high-salt wastewater

An efficient and stable catalyst is the key to electrocatalytic hydrogen production. Herein, a bifunctional electrocatalyst is developed for electrocatalytic hydrogen production by depositing S-doped g-C3N4 on Co/Ni metal-organic framework electrode (namely CoNi-MOFs/S-g-C3N4). Compared with the original Co/Ni metal-organic framework (CoNi-MOFs), the overpotential of hydrogen production on CoNi-MOFs/S-g-C3N4 is reduced by 49.5 %, the charge transfer resistance is reduced by 74.5 %, and the electrochemically active area is expanded by 60.1 times. Moreover, CoNi-MOFs/S-g-C3N4 can be used as an efficient bifunctional electrocatalyst for overall water splitting. Impressively, using CoNi-MOFs/S-g-C3N4 as the anode and cathode, the hydrogen yield can reach 5.513 mmol h−1 and the energy consumption is 5.822 kWh Nm−3 at a current density of 250 mA cm−2. In addition, an in-situ overall water splitting system was designed for hydrogen production using high-salt wastewater as water source without additional pre-desalination process, which realizes green hydrogen production and reduces the cost. The hydrogen yield was hold in the range of 5.2–5.3 mmol h−1 for a week, showing excellent performance of hydrogen production and strong stability. More importantly, the system can be applied to various high-salt wastewater with wider pH and salinity, and shows promising application potential for hydrogen production in actual wastewater.

2D/2D Schottky-type hybrid heterocatalyst comprising S-doped g-C3N4 and delaminated Ti3C2 MXene: Synergistic interplay of dual strategies for effective H2 generation and pollutant degradation

The quest for sustainable solutions to environmental pollution and energy scarcity has prompted the exploration of advanced photocatalytic materials. This study introduces an efficient 2D/2D Schottky-type hybrid heterocatalyst that combines sulfur-doped 2D g-C3N4 (SCN) with delaminated 2D Ti3C2 (TC) MXene, designed for effective H2 generation and antibiotic pollutant degradation under visible light. This hybrid system leverages the synergistic interplay of two strategies: electronic band structure engineering and conductive TC MXene cocatalyst integration, addressing the critical limitations inherent in g-C3N4. The TC-4/SCN hybrid, with its optimized TC content, exhibits exceptional photocatalytic performance, achieving an H2 production yield of 79.5 μmol over 5 h and an apparent quantum efficiency of 9.2 %. Moreover, this hybrid demonstrates significant effectiveness in degrading and mineralizing the antibiotic levofloxacin, surpassing g-C3N4, SCN, other TC/SCN hybrids, and several advanced photocatalysts previously reported. Detailed characterization and mechanistic investigations attribute the outstanding photocatalytic activity to efficient charge transfer, separation, reduced recombination rates, strong optical absorption, and a large specific surface area, all of which are facilitated by the dual strategies employed in creating the 2D/2D Schottky-type heterojunction. Furthermore, reusability tests confirmed the durability and stability of the TC-4/SCN, highlighting its practical applicability for repeated use in environmental and energy applications.

Boosting visible-light-promoted photodegradation of norfloxacin by S-doped g-C3N4 grafted by NiS as robust photocatalytic heterojunctions

As a result of industrial expansion and ill-considered exploitation of resources, serious environmental issues have recently emerged that have led to damage to the ecosystem. In particular, antibiotics, such as norfloxacin (NOR) have emerged as highly hazardous contaminants resulting from the increased use of these drugs worldwide. Photocatalysis-based degradation using heterojunctions has become almost the only way to permanently and eco-friendly degrade these pollutants. Herein, noble metal-free nanohybrids composed of S-doped g-C3N4 grafted by NiS (denoted as NiS/SCN) have been fabricated via hydrothermal and one-step polymerization (at 550 °C) procedures. The photocatalytic activity of 3 %NiS/SCN photocatalyst was almost 6- and 20-times as high as SCN and NiS, respectively, achieving 96.2 % NOR degradation within 90 min. The recommended photocarriers transfer pathway was suggested and supported experimentally. Considerably, loading a small amount of NiS cocatalyst over S-doped g-C3N4 boosted performance in addition to efficient reusability. This increased photocatalytic activity can be attributed to the fact that doping g-C3N4 with sulfur can reduce the bandgap and thus broaden the response range to visible-light, and the effective effect of Schottky junction can significantly improve the separation rate of electron-hole pairs. Accordingly, the constructed NiS/SCN nanocomposites are potential candidates for photocatalysis processes, particularly visible-light-induced degradation of organic pollutants.

Mesoporous sulfur-doped g-C3N4@attapulgite composite as an advanced photocatalyst for efficiently uranium(VI) recovery from aqueous solutions

Photocatalytic reduction of uranium(VI) via g-C3N4 is a promising and efficient method for the recovery of radioactive uranium contamination from wastewater. In this work, the mesoporous sulfur-doped g-C3N4@attapulgite composite was first synthesized via a two-step hydrothermal-roasting method with (NH4)2S2O8 as the sulfur source and attapulgite as the supporter, respectively. As expected, the recovery efficiency of uranium(VI) using S-doped g-C3N4 was 1.80 times higher than that of g-C3N4. Additionally, compared to S-doped g-C3N4, the mesoporous S-doped g-C3N4@attapulgite composite exhibited further improved photocatalytic efficiency and stability. The experimental results further showed the uranium(VI) was quickly eliminated within 20 min by mesoporous S-doped g-C3N4@attapulgite, and the recovery rate of which remained at 88.4 % even after seven cycles. According to the XPS results and trapping experiments, the excellent uranium(VI) recovery and stability can be attributed to the adsorption capacity of attapulgite and the e- reduction from sulfur doping g-C3N4, respectively. This result contributes to understanding the enhanced photocatalytic reduction mechanism of uranium(VI) and to achieving the high-efficiency recovery of uranium from wastewater using the mesoporous S-doped g-C3N4@attapulgite composite.

Preparation and Performance Study of S-Doped g-C3N4 Photocatalyst

In order to further improve the photocatalytic performance of pure CN, SCN (1:1), SCN (1:2), and SCN (2:1) photocatalysts were prepared using a one-step thermal polymerization method. The morphology of the prepared pure CN and SCN was characterized using SEM, XRD, UV, PL, and XPS to identify the reasons for their improved performance. Proved the photocatalytic degradation effect of prepared CN and SCN on RhB solution. The photocatalytic degradation efficiency of RhB by SCN (1:1) is 90.3%, which is nearly 1.72 times higher than that of CN52.38%. After a series of characterization, it was found that the SCN photocatalyst layer is thinner than the CN photocatalyst layer, and a large number of micron sized pores are distributed on the surface of SCN, increasing the specific surface area of SCN. Introducing an appropriate mass ratio of S element will improve the crystallinity of SCN photocatalysts. An appropriate mass ratio of SCN can reduce the band gap, which decreases from 2.70 eV corresponding to CN to 2.62 eV (1:1) of SCN. The photoresponse range undergoes a red shift, which is beneficial for the photocatalytic reaction and thus improves the performance of the photocatalyst. SCN can inhibit the recombination of photo generated electrons and holes, and improve the activity of photocatalysts.

Synthesis of S-doped g-C3N4 nanostructures by reflux method and study of photocatalytic and photoelectrochemical performances

For the first time, the S-doped g-C3N4 nanostructures (SCN(x)) were prepared by the reflux method as an aqueous-based method with different weight ratios of Na2S (x) and then characterized. The results of S-doped g-C3N4 nanostructures confirmed the presence of sulfur doping in the g-C3N4 structure. Moreover, these nanostructures showed superior photocatalytic efficiency compared to the bulk g-C3N4. Among different SCN(x) nanostructures, SCN(0.2) showed the most remarkable photocatalytic performance. This outcome is attributed to a decrease in the band gap of this sample. The FESEM analysis indicated that the nanoparticles tended to adhere together in SCN(0.2) nanostructure. This phenomenon has led to the reduction of surface roughness, and improving the surface texture quality of this nanostructure. On the other hand, the lowest FWHM and PL peak intensity show an increase in crystallinity and a decrease in the amount of recombination in this nanostructure. Moreover, the evaluation of electrochemical impedance and optical current showed a decrease in the semi-circular pattern and an increase in photocurrent for the optimal sample of SCN (0.2) compared to the bulk g-C3N4. Therefore, the results of investigating the photocatalytic performance of the synthesized nanostructures show that the SCN(x) nanostructures have higher efficiency compared to the bulk g-C3N4. In addition, the SCN(0.2)) sample showed the highest photocatalytic efficiency. Compared to the other conventional deposition methods based on electrostatic or van der Waals forces, this study suggests that using the reflux technique to substitute sulfur in the g-C3N4 can be a successful approach due to the chemical bonding on to host framework. Moreover, this method may provide a facile aqueous-based route for doping in the g-C3N4 layered structure and can offer advantages compared to other common method such as simple, low cost, excellent distribution uniformity, fast reaction kinetics, high levels of purity, and environmentally friendly process.

S-doped g-C3N4 for fluorescence sensing of Fe3 + and photocatalytic dye degradation under solar light

Sulfur doped graphitic carbon nitride nanosheets were synthesized via polycondensation reaction of urea-thiourea mixture. Structure and morphology were characterized by XRD (X-ray diffraction), SEM (scanning electron microscope), and XPS (X-ray Photoelectron Spectroscopy). DRS (diffuse reflectance spectroscopy), PL (Photoluminescence spectroscopy) and time-resolved fluorescence decay spectra were used to study the optical characteristics. The photocatalytic dye degradation of Rhodamine B (RhB) in the presence of as-synthesized catalysts was investigated with the help of a UV–visible spectrophotometer. The photocatalytic activity of carbon nitride prepared from urea-thiourea mixture is almost three times higher than that of the pure sample. The detection of Fe3+ was also investigated by using the fluorescence sensing method. The as-synthesized samples hold greater selectivity and sensitivity for fluorescence sensing of Fe3+within a range of 0–3 µM. This range is comparable to the performance of other Fe3+ fluorescent probes previously reported.

Sulfur-Doped g-C3N4 Heterojunctions for Efficient Visible Light Degradation of Methylene Blue.

The discharge of synthetic dyes from different industrial sources has become a global issue of concern. Enormous amounts are released into wastewater each year, causing concerns due to the high toxic consequences. Photocatalytic semiconductors appear as a green and sustainable form of remediation. Among them, graphitic carbon nitride (g-C3N4) has been widely studied due to its low cost and ease of fabrication. In this work, the synthesis, characterization, and photocatalytic study over methylene blue of undoped, B/S-doped, and exfoliated heterojunctions of g-C3N4 are presented. The evaluation of the photocatalytic performance showed that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75 mass % of S-doped (g-C3N4) present enhanced activity with an apparent reaction rate constant (kapp) of 1.92 × 10-2 min-1 for the 75% sample. These results are supported by photoluminescence (PL) experiments showing that this heterojunction presents the less probable electron-hole recombination. UV-vis diffuse reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS) allowed the calculation of the band-gap and the valence band positions, suggesting a band structure diagram describing a type I heterojunction. The photocatalytic activities calculated demonstrate that this property is related to the surface area and porosity of the samples, the semiconductor nature of the g-C3N4 structure, and, in this case, the heterojunction that modifies the band structure. These results are of great importance considering that scarce reports are found concerning exfoliated B/S-doped heterojunctions.

P/S-g-C3N4 nanosheet composites with enhanced photocatalytic water splitting and dye degradation

The band gap and photo- and electro-chemical activities of graphic carbon nitride (g-C3N4) depended strongly on their components. In this paper, P-g-C3N4/S-g-C3N4 (PCN/SCN) and S-g-C3N4/P-g-C3N4 (SCN/PCN) composite nanosheets heterostructures were created using P-doped and S-doped g-C3N4 nanosheets as seeds to study the effect of compositions on photo- and electro-chemical properties. Thermal polymerization temperature and the ratios of S- and P-doped g-C3N4 components were adjusted to get optimized conditions. The photo-degradation kinetics of Rhodamine B (Rh B) and photocatalytic H2 generation were used to discuss the relationship of photocatalytic performance and composition of photocatalysts. The degradation of Rh B in visible light region was finished using sample 600MCNS@ 720 DCNP15% within 15 min with a degradation rate constant of 0.197, which was 2.3 and 3.9 times compared with S- and P-doped g-C3N4 nanosheets, respectively. Namely, the H2 generation rate of sample 600MCNS@ 720 DCNP15% was 1851.9 µmolg−1h−1, which is 6.6 and 5.9 times higher than those of S- and P-doped g-C3N4 nanosheets, respectively. Interestingly, these P/S-g-C3N4 composite heterojunctions revealed improved electro-chemical performance. In the case of a current density of 1 mA cm−2, the overpotential of ample 600MCNP@ 720 DCNS20% was 333 mV and a Tafel slope was 155.33 mV dec−1 in KOH solutions. This result supplied an efficient approach to improve the photocatalytic performance of g-C3N4 based materials.

Enhancing O2 adsorption and activation over porous S-doped g-C3N4 rod toward efficient photocatalytic rhodamine-B degradation

Photocatalytic oxygen molecular (O2) activation to generate reactive oxygen species (ROS) is a promising strategy for the oxidative degradation of organic pollutants. Herein, a porous S-doped g-C3N4 rod (S-g-CN-rod) was synthesized and applied to photocatalytic superoxide radicals (·O2-) evolution and rhodamine-B (RhB) degradation. The morphological, structural, and optical properties of all samples were investigated. DFT calculation demonstrated that the carbon site adjacent to S was energetically favorable for O2 adsorption, which was conducive to ·O2- evolution. The porous S-g-CN-rod exhibited an excellent photocatalytic ·O2- evolution rate of 268.2 μmol L−1 h−1, which was the main active species to degrade RhB. Conceivably, the porous S-g-CN-rod demonstrated exceptionally high efficiency of photocatalytic RhB degradation and achieved almost complete disposal of RhB (99.7 %) in only 30 min, which was higher than most reported photocatalysts. The experimental results and theoretical calculations demonstrated that the preeminent photocatalytic activities were ascribed to enhanced light-harvesting, improved migration and separation of photo-induced electrons, and the superior O2 adsorption and activation induced by S doping.

Performance and mechanism investigation on the enhanced photocatalytic removal of atrazine on S-doped g-C3N4

Developing efficient method for removing low-concentration atrazine, a poisonous chlorinated triazine herbicide with poor biodegradability, was an important measure to control its risk. In this work, highly efficient photocatalytic oxidation of atrazine was achieved on S-doped g-C3N4 (S-g-C3N4). Approximate 99.6% of atrazine was removed in 2 h with a reaction rate constant of 2.76 h−1, nearly 2.44 times that on g-C3N4. The mechanism investigation indicated the improved photocatalytic performance of S-g-C3N4 could be attributed to the enlarged specific surface area, extended light absorption as well as the accelerated separation of the photogenerated charge carriers, which was brought about by the successful doping of sulfur in g-C3N4. Meanwhile, the influence of sulfur doping on the generation and contribution of different reactive species in atrazine removal were also elucidated. It revealed that compared with g-C3N4, the more positive valence band potential of S-g-C3N4 was beneficial to produce more singlet oxygen, which could react synergistically with the superoxide radicals, leading to the improved atrazine removal efficiency. The S-g-C3N4 based photocatalytic system also showed preferential photocatalytic oxidation capability in removing other triazine pesticides compared with 3-chlorophenol (3-CP). The potential applicability of the S-g-C3N4 based photocatalytic system in removing atrazine in high salty water was also investigated, which exhibited superior anti-interference ability towards virous coexistent ions. This work will provide essential and fundamental information for establishing efficient photocatalytic system for triazine type pollutants in waters.

One-step synthesis of S-doped C-vacancy g-C3N4 with honeycomb porous nanosheets structure for efficient visible-light-driven hydrogen evolution

A defective construction method was applied to design the molecular framework from the source and use the intermolecular forces of the raw materials to connect the long chains. The S-doped honeycomb g-C3N4 nanosheets were prepared by selective volatilization at elevated temperatures using melamine-tricyanuric acid-thiourea supramolecular liquid as precursor and template. In addition to significantly increasing the high surface area, the S-doped honeycomb g-C3N4 nanosheets also modify the band gap structure and shape. The introduction of the C defect also increased the number of reaction sites, improved visible light responsiveness, broadened the photoresponse range, and accelerated the segregated transfer of photogenerated carriers. The experimental results showed that the hydrogen production efficiency of S-PDCN-3 (The best sample of S-doped C-vacancy g-C3N4) is 23.78 mmol‧g−1‧h−1, which was 21.8 times that of BCN, namely Bulk g-C3N4 (1.1 mmol‧g−1‧h−1). After adding the photosensitizer (Erythrosin B) to the photocatalytic reaction system, EB + S-PDCN-3 (the best sample of S-doped honeycomb g-C3N4 nanosheets with the sensitizer) precipitated hydrogen up to 63.8 mmol‧g−1‧h−1, which was 17.78 times greater than the hydrogen production of the EB + BCN sample (3.59 mmol‧g−1‧h−1). Furthermore, the sample was observed to experience a reduction in band gap energy, an increase in electron density near VB and a reduction of H* adsorption–desorption barrier, all of which are essential for the enhancement of the hydrogen evolution reaction. Successful preparation of S-doped honeycomb g-C3N4 nanosheets provides a simple and efficient method for developing efficient g-C3N4 photocatalysts—potential applications in the development process of hydrogen energy and pollutant degradation.

Pt-functionalized S-doped g-C3N4 nanosheet for sensitive electrochemical determination of sulfamonomethoxine

Pt-functionalized S-doped g-C3N4 nanosheet for sensitive electrochemical determination of sulfamonomethoxine

Preparation of high-crystalline and non-metal modified g-C3N4 for improving ultrasound-accelerated white-LED-light-driven photocatalytic performances

As a non-metallic organic semiconductor, graphitic carbon nitride (g-C3N4) has received much attention due to its unique physicochemical properties. However, the photocatalytic activity of this semiconductor faces challenges due to factors such as low electronic conductivity and limited active sites provided on its surface. The morphology and structure of g-C3N4, including macro/micro morphology, crystal structure and electronic structure can affect its catalytic activity. Non-metallic heteroatom doping is considered as an effective method to tune the optical, electronic and other physicochemical properties of g-C3N4. Here, we synthesized non-metal-doped highly crystalline g-C3N4 by one-pot calcination method, which enhanced the photocatalytic activity of g-C3N4 such as mesoporous nature, reduced band gap, wide-range photousability, improved charge carrier recombination, and the electrical conductivity was improved. Hence, the use of low-power white-LED-light illumination (λ ≥ 420 nm) and ultrasound (US) irradiation synergistically engendered the Methylene Blue (MB) mineralization efficiency elevated to 100% within 120 min by following the pseudo-first-order mechanism under the following condition (i.e., pH 11, 0.75 g L−1 of O-doped g-C3N4 and S-doped g-C3N4, 20 mg L−1 MB, 0.25 ml s−1 O2, and spontaneous raising temperature). In addition, the rapid removal of MB by sonophotocatalysis was 4 times higher than that of primary photocatalysis. And radical scavenging experiments showed that the maximum distribution of active species corresponds to superoxide radical {mathrm{O}}_{2}^{cdot-}. More importantly, the sonophotocatalytic degradation ability of O-doped g-C3N4 and S-doped g-C3N4 was remarkably sustained even after the sixth consecutive run.

Green Synthesis Strategy of Template-Free S-Doped g-C3N4 with Cystine for Efficient Photocatalytic Degradation of RhB.

Constructing a nanostructure with a high surface area and regulating the band gap by nonmetallic doping are two effective methods for improving the photocatalytic activity of catalysts. A green template-free synthesis strategy of S-doped g-C3N4 nanosheets is proposed via doping cystine as both the structural additive and S source. The features of S-doped samples (GCN-x%) were systematically studied, including morphology and textural and photoelectric properties, which demonstrated that the introduction of cystine and simple manipulation of the preparation process could realize self-exfoliation of g-C3N4 into nanosheets. The GCN-3% sample showed a surface area (131.88 m2·g-1) 10.7 times enlarged compared with bulk g-C3N4 (bulk-phase carbon nitride). Obvious redshift on the absorption edge induced by S doping can be observed, revealing a narrowed band gap and enhanced efficiency of photogenerated charge carrier separation. The DFT calculation results also verified that the introduced C-S site could lead to polarization of the local electric field and thus decrease the bandgap of g-C3N4 nanosheets. GCN-3% showed a 99.3% photocatalytic degradation ratio of rhodamine B in 60 min at a rate of 0.17 min-1. By scavengers experiment revealed that superoxide anion (·O2-) radicals and holes (h+) were vital active components during the photocatalytic degradation.