Sulfur-doped g-C3N4 Nanosheets Research Articles

Combined experimental and DFT investigation of temozolomide sensing properties of 2D− 2D interface of rich oxygen vacancies of WO3−x and sulfur-doped g-C3N4 nanosheets hybrids composites

Temozolomide (TMZ) is one of the most effective anticancer drug and higher the risk of side effects, used in overdosage in cancer treatment. It is a major concern to determine the appropriate level of the anticancer drug by a more conventional method. In the present study, the first developed 2D− 2D interface of rich oxygen vacancies of WO3 −x and sulfur-doped g-C3N4 nanosheets hybrids composites (2D–2D/RWNs-SCN) was synthesized using a facial microwave-assisted route to detection of temozolomide (TMZ) in pharmaceutical sample. The samples’ morphological, two-dimensional rich oxygen vacancies of WO3 −x nanosheets (2D RWNs) and sulfur-doped g-C3N4 nanosheets (2D SCN) were investigated using field emission-scanning electron microscopes (FE-SEM). The 2D–2D/RWNs-SCN modified screen-printed carbon electrodes (SPCEs) were utilized for reducing TMZ in a 0.1 M phosphate-buffered solution (pH 7.0). The 2D–2D/RWNs-SCN achieved a higher reduction current against TMZ than the bare SPCE, CN/SPCE, SCN/NSs/SPCE, and 2D RWNs/SPCE. With optimized sensing parameters, the limit of detection was estimated to be 0.0019 μM, with a high sensitivity of 18.2855 μA μM− 1 cm− 2. To corroborate our experimental observations qualitatively, we have first time performed detailed density functional theory simulations to explore the charge transfer and bonding mechanism of TMZ on 2D RWNs and 2D–2D/RWNs-SCN surface. The higher binding energy of TMZ and enhanced charge transfer from TMZ to 2D–2D/RWNs-SCN owing to the 2D–2D interface possess superior charge-transfer kinetics, resulting in higher TMZ sensing performance, which supports our experimental observations. The hybrid nanocomposites are successfully applied to the determination of TMZ in the presence of pharmaceutical samples.

ZnAl2O4/sulfur-doped g-C3N4 S-scheme heterojunction for efficient photocatalytic degradation of malachite green

In this study, ZnAl2O4 and sulfur-doped g-C3N4 (SCN) S-Scheme heterojunctions were successfully prepared by in situ self-assembly method for the efficient removal of malachite green (MG). The composite structure was formed by loading ZnAl2O4 nanoscale particles onto SCN nanosheets. The results showed that the 30 wt% ZnAl2O4/SCN composite exhibited the best photocatalytic properties. The degradation of malachite green (MG) by 30 wt% ZnAl2O4/SCN composite reached 98.3% after 120 min of simulated solar illumination. Photo-induced •O2− was regarded as the primary active substance in the MG photodegradation. This study is expected to provide new possible strategies for the removal of contaminants MG in water.

Synergistic effects of holey nanosheet and sulfur-doping on the photocatalytic activity of carbon nitride towards NO removal

Photocatalysis provides a sustainable way for NOx elimination. However, efficient and safe photocatalytic removal of NOx remain a great challenge due to the limited light-harvesting ability and quick recombination of charge carriers. Herein, holey sulfur-doped g-C3N4 nanosheets (CNN–S) was reported by directly calcining a mixture of hydrolyzed dicyandiamide and thioacetamide. The specific surface area of the pristine g-C3N4 nanosheets (CNN–S0) is 3–4 times higher than bulk g-C3N4 (BCN), and the photocatalytic NO removal rate also increased from 17% (BCN) to 35% (CNN–S0). The effect of sulfur content on the photocatalytic performance was systematic studied, and CNN–S0.5 sample exhibits the highest NO removal rate (53%). The high photoreactivity of S-doped g-C3N4 nanosheets can be attributed to enhanced visible light absorption, increased specific surface area, and effective separation and transfer of photo-generated charges owing to the synergistic effect of the nanosheet structure and sulfur doping. In addition, density functional theory calculations show that the doping of S is also beneficial to the adsorption and activation of the reactants on CN.

Superior antibacterial activity of sulfur-doped g-C3N4 nanosheets dispersed by Tetrastigma hemsleyanum Diels & Gilg's polysaccharides-3 solution

Bacterial resistance has become a serious global health issue over the past decades due to the misuse and abuse of antibiotics. The development of effective antibacterial drugs with a new antibacterial mechanism is thus very critical. At present, there are many reports on the antibacterial properties and mechanisms of two-dimensional materials. Currently, the modification of g-C3N4 materials, as widely used two-dimensional materials, has become a key step in extending their potential applications in the field of antimicrobial therapy. In the present work, we prepared sulfur-doped g-C3N4 nanosheets (SCNNSs), which have good water dispersibility and sharp tips. The electrostatic interaction of SCNNSs with Tetrastigma hemsleyanum Diels & Gilg's polysaccharide-3 (THDG-3) provides a new strategy that can improve the killing efficiency of SCNNSs. In addition, THDG-3 can rapidly inhibit bacterial proliferation in the early stage of administration. Combined with the antibacterial activity of the SCNNSs, TPS/SCNNSs can inhibit bacteria for a long time. Scanning electron microscopy (SEM) observation of Escherichia coli (E. coli) after administration of the materials revealed that the bacterial cells were ruptured and their intracellular contents were completely separated from the cell membrane. Therefore, we speculate that the bactericidal mechanism of the TPS/SCNNSs probably involves cell membrane damage. In summary, TPS/SCNNSs achieve fast, long-term, dual-function bacteriostatic properties.

Sulfur-doped g-C3N4 nanosheets for photocatalysis: Z-scheme water splitting and decreased biofouling

In this study, an S-doped g-C3N4 nanosheet was prepared as a photocatalyst for effective oxygen evolution reaction. Sulfur plays a crucial role in S-doped g-C3N4 not only in increasing the charge density but also in reducing the energy band gap of S-doped g-C3N4 via substitution of nitrogen sites. S-doped g-C3N4 can serve as an oxygen-evolved photocatalyst, when combined with Ru/SrTiO3:Rh in the presence of [Co(bpy)3]3+/2+ as an electron mediator, enables photocatalytic overall water splitting under visible light irradiation with hydrogen and oxygen production rates of 24.6 and 14.5 μmol-h−1, respectively. Moreover, the photocatalytic overall water splitting to produce H2 and O2 using this Z-scheme system could use for five runs to at least 94.5 h under visible light irradiation. On the other hand, S-doped g-C3N4 can reduce biofouling by bacteria such as Escherichia coli by more than 70%, by simply incubating the S-doped g-C3N4 sample with bacterial solution under light irradiation. Our results suggest that S-doped g-C3N4 is a potentially effective, green, and promising material for a variety of photocatalytic applications.

Sulfur-doped g-C3N4 nanosheets with carbon vacancies: General synthesis and improved activity for simulated solar-light photocatalytic nitrogen fixation

Ultrathin sulfur-doped g-C3N4 porous nanosheets (SCNNSs) with large lateral size and carbon vacancies were obtained by directly collecting the gaseous product of thiourea under a self-generated NH3 atmosphere. The NH3 atmosphere promoted the formation of sulfur doped g-C3N4 nanosheets with a hierarchical pore structure and a high specific surface area. Carbon vacancies were also generated in the SCNNSs without notably changing the overall chemical structure. The obtained SCNNSs-550 showed a photocatalytic nitrogen fixation rate of 5.99 mM h−1 gCat−1 under simulated sunlight irradiation within 4 h, which is 2.8 times as high as that of bulk SCN. This superior photocatalytic performance of SCNNSs was attributed to the porous sheet structure with sulfur doping and carbon vacancies, which provide many active sites for surface reactions and increase the charge-carrier separation rate. This novel synthetic method provides a simple and efficient way to dope non-metals and form a defect structure in g-C3N4 for excellent photocatalytic performance.