Solid-State Method Synthesis of SnO₂-Decorated g-C₃N₄ Nanocomposites with Enhanced Gas-Sensing Property to Ethanol

Photocatalytic removal of some selected antibiotics in polluted water system by graphitic carbon nitride-enhanced vanadium ferrite (VFe2O4@g-C3N4)

Antibiotics such as sulfamethoxazole (SUF), ciprofloxacin (CIP) and erythromycin (ERY) are frequently detected in water systems without being efficiently removed during water treatment. This study synthesized a graphitic carbon nitride-enhanced vanadium ferrite (VFe2O4@g-C3N4) as a photocatalyst for degrading SUF, CIP and ERY in an aqueous solution. VFe2O4@g-C3N4 was characterized with X-ray diffractometry (XRD), thermogravimetry analysis (TGA), ultraviolet (UV)-visible spectrophotometry, scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD characterization of VFe2O4@g-C3N4 revealed diffraction patterns with a crystallite size of 22.45 nm and a bandgap energy of 1.94 eV. The SEM image revealed the surface to be rough with irregular particle shape and size. The TEM image showed an average particle size of 92.47 nm. VFe2O4@g-C3N4 exhibited a degradation efficiency, which showed complete removal of SUF (100 %) from solution while the efficiency towards CIP is 94 ± 0.60 % and 90 ± 0.8 % towards ERY. The best photocatalytic performance was achieved with 0.12 g L-1 of VFe2O4@g-C3N4 and pH = 7.0 as the optimal conditions for achieving complete removal of SUF, CIP and ERY at a concentration lower than 10.00 mg L-1 under visible-light irradiation. The photodegradation of SUF, CIP and ERY by VFe2O4@g-C3N4 was found to be promoted by ROS with ˙OH and SO4˙- radicals playing a significant role. VFe2O4@g-C3N4 demonstrated a regeneration capacity that is above 90 % at the 10th cycle of regeneration treatment, suggesting it to be stable and reusable with the X-ray diffraction pattern remaining unchanged and no leaching of VFe2O4@g-C3N4 into solution. The result from the study reveals VFe2O4@g-C3N4 as a promising photocatalyst for removing antibiotics from an aqueous solution.

Piezo-Flexocatalysis of Single-Atom Pt-Loaded Graphitic Carbon Nitride

This study develops a single-atom Pt-loaded graphitic carbon nitride (SA-Pt/CN) and evaluates its piezo-flexocatalytic properties by conducting a hydrogen evolution reaction (HER) and Rhodamine B (RB) dye degradation test under ultrasonic vibration in the dark. SA-Pt/CN has a hydrogen gas yield of 1283.8 µmol g-1 h-1, which is 23.3 times higher than that of pristine g-C3N4. Moreover, SA-Pt/CN enhances the dye degradation reaction rate by ≈2.3 times compared with the pristine sample. SA-Pt/CN exhibits lattice distortion and strain gradient enlargement caused by the single atom Pt at the N sites of g-C3N4, which disrupts the symmetric structure and contributes to the enhancement of piezoelectric and flexoelectric polarization. As far as it is known, this is the first study to investigate the piezo-flexocatalytic reaction of SA-Pt/CN without light irradiation and provides new insights into single-atom piezocatalysts.

Nano-size cobalt-doped cerium oxide particles embedded into graphitic carbon nitride for enhanced electrochemical sensing of insecticide fenitrothion in environmental samples: An experimental study with the theoretical elucidation of redox events

In the present work, a nanocomposite, based on embedding Co-doped CeO2 nanoparticles into graphitic carbon nitride (g-C3N4), was applied to functionalize commercial glassy carbon paste. This is the first application of the electrochemical sensor, developed through the proposed procedure, in electrochemical sensing. The sensor was utilized for the electrochemical determination of organophosphate pesticide fenitrothion (FNT). Cyclic voltammetry identified reversible oxidation of FNT (oxidation at 0.18 V and reduction at 0.13 V) and additional reduction at -0.62 V vs. Ag/AgCl in HCl solution (pH = 1). Theoretical calculations were carried out to model and elucidate experimentally observed redox processes. Special attention was devoted to modeling experimental conditions, and based on the obtained results, a detailed redox mechanism of the investigated analyte was proposed. This represents the first complete and unambiguous elucidation of the FNT redox mechanism, supported by joined experimental and theoretical data. Square wave voltammetry (SWV) was utilized for quantification, whereby the FNT oxidation peak was chosen for monitoring the analyte concentration. The developed sensor provided a nanomolar detection limit (3.2 nmol L-1), a wide linear concentration range (from 0.01 to 13.7 μmol L-1), and good precision, repeatability, and selectivity towards FNT. Practical application possibility was explored by testing the sensor performance for examining tap water and apple samples. Recovery tests, conducted during the FNT-spiked sample assays, showed a great application capability of the developed sensor for real-time monitoring of FNT traces in environmental samples.

Synthesis of novel antibacterial and biocompatible polymer nanocomposite based on polysaccharide gum hydrogels

According to recent studies on the benefits of natural polymer-based hydrogels in biomedical applications, gellan gum (GG)/acacia gum (AG) hydrogel was prepared in this study. In order to regulate the mechanical behavior of the hydrogel, graphite carbon nitride (g-C3N4) was included in the hydrogel matrix. In addition, metal oxide nanoparticles ZnCuFe2O4 were added to the composite for antibacterial activity. The prepared GG-AG hydrogel/g-C3N4/ZnCuFe2O4 nanobiocomposite was characterized by using FE-SEM, FTIR, EDX, XRD and TGA. The nanobiocomposite exhibited spherical morphology, which was related to the incorporation of the metal oxide nanoparticles. GG-AG hydrogel/g-C3N4/ZnCuFe2O4 nanobiocomposite showed 95.11%, 92.73% and 88.97% biocompatibility toward HEK293T cell lines within 24 h, 48 h and 72 h incubation, respectively, which indicates that this nanobiocomposite is completely biocompatible with healthy cells. Also, the nanobiocomposite was able to inhibit Pseudomonas aeruginosa biofilm growth on its surface up to 87%. Rheological studies showed that the nanobiocomposite has a viscoelastic structure and has a water uptake ratio of 93.2%. In comparison with other similar studies, this nanobiocomposite has exhibited superior antibacterial activity complete biocompatibility and proper mechanical properties, high swelling and water absorption capability. These results indicate that GG-AG hydrogel/g-C3N4/ZnCuFe2O4 nanocomposite can be considered as a potential candidate for biomedical applications such as tissue engineering and wound healing.

Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts

The preparation of visible-light-driven photocatalysts has become highly appealing for environmental remediation through simple, fast and green chemical methods. The current study reports the synthesis and characterization of graphitic carbon nitride/titanium dioxide (g-C₃N₄/TiO₂) heterostructures through a fast (1 h) and simple microwave-assisted approach. Different g-C₃N₄ amounts mixed with TiO₂ (15, 30 and 45 wt. %) were investigated for the photocatalytic degradation of a recalcitrant azo dye (methyl orange (MO)) under solar simulating light. X-ray diffraction (XRD) revealed the anatase TiO₂ phase for the pure material and all heterostructures produced. Scanning electron microscopy (SEM) showed that by increasing the amount of g-C₃N₄ in the synthesis, large TiO₂ aggregates composed of irregularly shaped particles were disintegrated and resulted in smaller ones, composing a film that covered the g-C₃N₄ nanosheets. Scanning transmission electron microscopy (STEM) analyses confirmed the existence of an effective interface between a g-C₃N₄ nanosheet and a TiO₂ nanocrystal. X-ray photoelectron spectroscopy (XPS) evidenced no chemical alterations to both g-C₃N₄ and TiO₂ at the heterostructure. The visible-light absorption shift was indicated by the red shift in the absorption onset through the ultraviolet-visible (UV-VIS) absorption spectra. The 30 wt. % of g-C₃N₄/TiO₂ heterostructure showed the best photocatalytic performance, with a MO dye degradation of 85% in 4 h, corresponding to an enhanced efficiency of almost 2 and 10 times greater than that of pure TiO₂ and g-C₃N₄ nanosheets, respectively. Superoxide radical species were found to be the most active radical species in the MO photodegradation process. The creation of a type-II heterostructure is highly suggested due to the negligible participation of hydroxyl radical species in the photodegradation process. The superior photocatalytic activity was attributed to the synergy of g-C₃N₄ and TiO₂ materials.

Synthesis of neodymium ferrite incorporated graphitic carbonitride (NdFe2O4@g-C3N4) and its application in the photodegradation of ciprofloxacin and ampicillin in a water system

Purification of antibiotic-contaminated drinking water sources is faced with limitations. Therefore, this study incorporated neodymium ferrite (NdFe2O4) in graphitic carbonitride (g-C3N4) to form NdFe2O4@g-C3N4 as a photocatalyst for removing ciprofloxacin (CIP) and ampicillin (AMP) from aqueous systems. X-ray diffraction (XRD) revealed a crystallite size of 25.15 nm for NdFe2O4 and 28.49 nm for NdFe2O4@g-C3N4. The bandgap is 2.10 and 1.98 eV for NdFe2O4 and NdFe2O4@g-C3N4, respectively. The transmission electron micrograph (TEM) images of NdFe2O4 and NdFe2O4@g-C3N4 gave an average particle size of 14.10 nm and 18.23 nm, respectively. Scanning electron micrograph (SEM) images showed heterogeneous surfaces with irregular-sized particles suggesting agglomeration at the surfaces. NdFe2O4@g-C3N4 (100.00 ± 0.00% for CIP and 96.80 ± 0.80% for AMP) exhibited better photodegradation efficiency towards CIP and AMP than NdFe2O4 (78.45 ± 0.80% for CIP and 68.25 ± 0.60% for AMP) in a process described by pseudo-first-order kinetics. NdFe2O4@g-C3N4 showed a stable regeneration capacity towards degradation of CIP and AMP with a capacity that is above 95% even at the 15th cycle of treatment. The use of NdFe2O4@g-C3N4 in this study revealed its potential as a promising photocatalyst for removing CIP and AMP in water systems.

Graphitic Carbon Nitride-Wrapped Metal-free PoPD-Based Biosensor for Xanthine Detection

A metal-free, enzymatic biosensor was developed using graphitic carbon nitride (g-C₃N₄)-wrapped poly-ortho-phenylenediamine (PoPD) for the determination of xanthine (Xn). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction confirmed the successful formation of the PoPD, g-C₃N₄ nanosheets and PoPD@g-C₃N₄ nanocomposite. Furthermore, the electrochemical behavior of the biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The prepared enzyme electrode exhibited maximum response at pH 7.5 with a response time of 5 s, and its sensitivity was 5.798 μAM^-1. The nanocomposite shows exceptional sensing capabilities for detecting Xn, having a wide linear range from 1 nM to 1 μM with a relatively low detection limit of 0.001 nM. The biosensor shows good stability (4 weeks) and reproducibility and can detect the presence of Xn from other interfering analytes. Validation of the biosensor with real samples obtained from Rohu (Labeo rohita) fish shows that the fabricated biosensor has the requisite potential to be used for Xn detection in meat samples.

Metal Oxide Heterostructures for Improving Gas Sensing Properties: A Review

Metal oxide semiconductor gas sensors are widely used to detect toxic and inflammable gases in industrial production and daily life. The main research hotspot in this field is the synthesis of gas sensing materials. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can exhibit superior gas sensing performance in response and selectivity compared with single phase. This review focuses on mainly the synthesis methods and gas sensing mechanisms of metal oxide heterostructures. A significant number of heterostructures with different morphologies and shapes have been fabricated, which exhibit specific sensing performance toward a specific target gas. Among these synthesis methods, the hydrothermal method is noteworthy due to the fabrication of diverse structures, such as nanorod-like, nanoflower-like, and hollow sphere structures with enhanced sensing properties. In addition, it should be noted that the combination of different synthesis methods is also an efficient way to obtain metal oxide heterostructures with novel morphologies. Despite advanced methods in the metal oxide semiconductors and nanotechnology field, there are still some new issues which deserve further investigation, such as long-term chemical stability of sensing materials, reproducibility of the fabrication process, and selectivity toward homogeneous gases. Moreover, the gas sensing mechanism of metal oxide heterostructures is controversial. It should be clarified so as to further integrate laboratory theory research with practical exploitation.

Rational Integration of ZIF-8 and BiPO4 for Energy Storage and Environmental Applications

Environmental pollution and energy storage are among the most pivotal challenges of today's world. The development of multifunctional materials is required to address these challenges. Our study presents the rational design and synthesis of a hybrid material (ZIF-8@BiPO₄) with dual functionality: an outstanding supercapacitor electrode and an excellent photocatalyst. The ZIF-8@BiPO₄ hybrid structure was obtained by conjoining zinc ions and 2-methylimidazole ligands toward BiPO₄ by a one-pot stirring route at room temperature. The ZIF-8@BiPO₄ resulted in considerably higher specific capacitance (Cs) (489 F g^-1 at a scan rate of 5 mV s^-1; 497 F g^-1 at a current density of 1 A g^-1) than that of pure BiPO₄ (358; 443 F g^-1) and ZIF-8 (185; 178 F g^-1) under the same conditions in a three-electrode cell using the 2 M KOH aqueous electrolyte. Afterward, an asymmetric supercapacitor (ASC) device was fabricated with BiPO₄ as the anode and ZIF-8@BiPO₄ as the cathodes, acquiring an outstanding Cs of 255 F g^-1 at a current density of 0.5 A g^-1 with significant cycling stability (81% over 10,000 cycles). Moreover, the ASC has an energy density of 17.5 Wh kg^-1and a power density of 13,695 W kg^-1, which can be considered to be at the borderline between batteries and supercapacitors. The photocatalytic activity of ZIF-8@BiPO₄ was further studied using a methylene blue (MB) dye and sildenafil citrate (SC) drug-active molecules. The degradation of MB was approximately 78% through the photocatalytic reduction after 180 min of UV irradiation. The outstanding characteristics together with the ecofriendly and low-cost preparation make ZIF-8@BiPO₄ appealing for a broad range of applications.

Evaluation of a photoelectrochemical platform based on strontium titanate, sulfur doped carbon nitride and palladium nanoparticles for detection of SARS-CoV-2 spike glycoprotein S1

This work aims to develop a photoelectrochemical (PEC) platform for detection of SARS-CoV-2 spike glyprotein S1. The PEC platform is based on the modification of a fluorine-doped tin oxide (FTO) coated glass slide with strontium titanate (SrTiO₃ or ST), sulfur-doped carbon nitride (g-C₃N₄-S or CNS) and palladium nanoparticles entrapped in aluminum hydroxide matrix (PdAlO(OH) or PdNPs). The PEC platform was denoted as PdNPs/CNS/ST/FTO and it was characterized by SEM, TEM, FTIR, DRX, and EIS. The PEC response of the PdNPs/CNS/ST/FTO platform was optimized by evaluating the effects of the concentration of the donor molecule, the nature of the buffer, pH, antibody concentration, potential applied to the working electrode, and incubation time. The optimized PdNPs/CNS/ST/FTO PEC platform was modified with 5 μg mL^-1 of antibody for determination of SARS-CoV-2 spike glycoprotein S1. A decrease in the photocurrent was observed with an increase in the concentration of SARS-CoV-2 from 1 fg mL^-1 to 1000 pg mL^-1 showing that the platform is a promising alternative for the detection of S1 protein from SARS-CoV-2. The designed PEC platform exhibited recovery percentages of 96.20% and 109.65% in artificial saliva samples.

Magnetic visible-light activated photocatalyst ZnFe2O4/BiVO4/g-C3N4 for decomposition of antibiotic lomefloxacin: Photocatalytic mechanism, degradation pathway, and toxicity assessment

Magnetic ZnFe₂O₄/BiVO₄/g-C₃N₄ (ZBC) composites were prepared via a facile hydrothermal and calcination method for the degradation of a representative antibiotics lomefloxacin (LFX) under visible light irradiation. The optimal photocatalyst ZBC-10 with a ZnFe₂O₄:BiVO₄:g-C₃N₄ mass ratio of 1:8:10 performed 96.1% removal of LFX after 105 min of illumination. The excellent performance is ascribed to the effective construction of heterojunctions and its capacity to form a double Z-scheme charge transmission pathway among the hosts in ZBC-10. The composite enhanced the separation and migration of photoexcited charge carriers and the effective generation of multiple active radicals including ·OH, ·O₂^-, and ¹O₂. The LFX degradation process, identified based on an integrated HPLC-Q-TOF-MS analysis and density functional theory computation of the Fukui indices, comprised of three pathways initiated by the opening of the piperazinyl ring, separation of piperazinyl and quinoline moieties, and cleavage of the pyridine ring on the quinoline moieties. Ecotoxicological evaluation confirmed the reduced toxicity of transformation intermediates over photocatalysis. Convenient magnetic recovery, high performance, and high recyclability made ZBC-10 a promising visible-light-activated photocatalyst for practical implementation in eliminating antibiotics from wastewater.

Promoting Electrocatalytic Reduction of CO2 to C2 H4 Production by Inhibiting C2 H5 OH Desorption from Cu2 O/C Composite

The electrochemical CO₂ reduction reaction (CO₂ RR) has great potential in realizing carbon recycling while storing sustainable electricity as hydrocarbon fuels. However, it is still a challenge to enhance the selectivity of the CO₂ RR to single multi-carbon (C₂₊ ) product, such as C₂ H₄ . Here, an effective method is proposed to improve C₂ H₄ selectivity by inhibiting the production of the other competitive C₂ products, namely C₂ H₅ OH, from Cu₂ O/C composite. Density functional theory indicates that the heterogeneous structure between Cu₂ O and carbon is expected to inhibit C₂ H₅ OH production and promote CC coupling, which facilitates C₂ H₄ production. To prove this, a composite electrode containing octahedral Cu₂ O nanoparticles (NPs) (o-Cu₂ O) with {111} facets and carbon NPs is constructed, which experimentally inhibits C₂ H₅ OH production while strongly enhancing C₂ H₄ selectivity compared with o-Cu₂ O electrode. Furthermore, the surface hydroxylation of carbon can further improve the C₂ H₄ production of o-Cu₂ O/C electrode, exhibiting a high C₂ H₄ Faradaic efficiency of 67% and a high C₂ H₄ current density of 45 mA cm^-2 at -1.1 V in a near-neutral electrolyte. This work provides a new idea to improve C₂₊ selectivity by controlling products desorption.

Facile construction of S-scheme SnO2/g-C3N4 photocatalyst for improved photoactivity

The SnO2/g-C3N4 composites were fabricated via an annealing mixture of g-C3N4 and SnO2, which were obtained from calcinating melamine and hydrothermal treatment of SnCl₄ solution, respectively. The photocatalytic properties of g-C3N4/SnO2 were studied over the degradation of Rhodamine B (RhB) under visible light, which exhibits a significantly improved photocatalytic activity compared to the single components, g-C3N4 and SnO2. The enhancement in photocatalytic activity of SnO2/g-C3N4 could be described by the S-scheme pathway, in which the effective charge transfer between components is demonstrated toward the suppression in recombination of the photogenerated electron-hole pairs within redox potential conservation. Besides, a new criterion, photochemical space-time yield, was applied to evaluate the photocatalytic performance of our samples.

Synthesis of highly efficient selenium oxide hybridized g-C3N4 photocatalyst for NADH/NADPH regeneration to facilitate solar-to-chemical reaction

An inexpensive graphitic carbon nitrite (g-C3N4) photocatalyst was hybridized with selenium oxide (SeO2) photocatalyst by a monolayer-dispersed technique. After hybridization of g-C3N4 with SeO2, the NADH/NADPH regeneration efficiency of SeO2 photocatalyst was enhanced under solar light illumination was observed. The photocatalytic activity of SeO2/g-C3N4 photocatalyst under solar light illumination was enhanced by 3-fold higher than g-C3N4 photocatalyst, the solar light photocatalytic activity was produced and the photo-decomposition of SeO2 photocatalyst was completely stifled after hybridized SeO2 photocatalyst by g-C3N4 photocatalyst. The improvement in performance and photo-decomposition inhibition under solar light illumination was persuaded by efficiency separation of photo-persuaded holes from SeO2 to the valence bond (V.B.)/highest occupied molecular orbital (HOMO) of g-C3N4 under solar light illumination, the electron jumped from the V.B. to the conduction band (C.B.)/lowest unoccupied molecular orbital (LUMO) of g-C3N4 could directly insert into the C.B. of SeO2 photocatalyst, synthesized SeO2/g-C3N4 photocatalyst is highly active for NADH/NADPH regeneration under solar light.

Fabrication of graphitic carbon Nitride/Nonstoichiometric molybdenum oxide nanorod composite with the nonmetal plasma enhanced photocatalytic hydrogen evolution activity

The extended light absorption and the prevented charge recombination are crucial for the graphitic carbon nitride (g-C₃N₄) based photocatalytic materials. Herein, nonstoichiometric molybdenum oxide (MoO_3-x) nanorods with oxygen vacancies were synthesized by a hydrothermal method with trace amount of oleylamine, and the Z-scheme two-dimentional (2D)/one-dimentional (1D) g-C₃N₄/MoO_3-x composites were prepared by a facile electrostatic assembling approach. The blue MoO_3-x nanorods with oxygen vacancies are loaded uniformly on the g-C₃N₄ nanosheets. The g-C₃N₄/MoO_3-x composite materials exhibit strong absorption in the visible and near-infrared light regions, and the improved charge separation efficiency through the Z-scheme charge transfer mechanism. The g-C₃N₄/MoO_3-x composite presents a significantly improved photocatalytic hydrogen generation activity with good cycling stability compared with sonicated g-C₃N₄ nanosheets. The best hydrogen generation activity of 209.2 μmol·h^-1 under solar light irradiation and the highest apparent quantum efficiency of 4.4% irradiated at 365 nm are obtained by the g-C₃N₄/MoO_3-x composite with a mass percent of 27.5%, which is 2.63 times of g-C₃N₄. The weight ratios and the content of oxygen vacancies in the small-size MoO_3-x nanorods have a significant influence on the photocatalytic hydrogen performance. Moreover, effective photocatalytic overall water splitting can be achieved with the H₂ and O₂ evolution rates of 0.755 and 0.368 μmol∙h^-1 by the g-C₃N₄/MoO_3-x composite. The novel g-C₃N₄/MoO_3-x composite will have broad prospects in the field of photocatalytic applications.

Recent advances in g-C3N4 based gas sensors for the detection of toxic and flammable gases: a review

In recent years, many 2D nanomaterials like graphene, MoS2, phosphorene, and metal oxide nanosheets have been investigated for gas sensing applications due to their excellent properties. Amongst other 2D nanomaterials, graphitic carbon nitride (g-C3N4) has attracted significant attention owing to its simple synthesis process, tunable electronic properties, and exceptional physicochemical properties. Such remarkable properties assert g-C3N4 as a potential candidate for the next-generation high-performance gas sensors employed in the detection of toxic and flammable gases. Although several articles and reviews are available on g-C3N4 for their synthesis, functionalities, and applications for the detection of humidity. Few of them has focused their attention on gas sensing using g-C3N4. Thus, in this review, we have methodically summed up the recent advances in g-C3N4 and its composites-based gas sensor for the detection of toxic and flammable gases. Moreover, we have also incorporated the synthesis strategies and the comprehensive physics of g-C3N4 based gas sensors. Additionally, different approaches are presented for the enhancement of gas sensing/detecting properties of g-C3N4 based gas sensors. Finally, the challenges and future scope of g-C3N4 based gas sensors for real-time monitoring of gases have been discussed.

Highly sensitive and wearable NO2gas sensor based on PVDF nanofabric containing embedded polyaniline/g-C3N4nanosheet composites

In this study, a highly flexible and wearable nitrogen dioxide (NO₂) gas sensor was fabricated based on electrospun poly(vinylidene fluoride) (PVDF)/polyaniline (PANi)/graphitic-carbon nitride (g-C₃N₄) blend nanocomposite (EBNC). g-C₃N₄/PANi nanocomposite (GPC) was synthesized byin situpolymerization technique prior to its incorporation into PVDF nanofibers, which ensured uniformity of dispersion. For the comparison study, PVDF/GPC nanocomposite film was fabricated using doctor blade technique. EBNC sensor exhibited high sensitivity, selectivity, reproducibility along with quick response and complete recovery. Electrospinning and GPC synergistically improved the performance of the EBNC based gas sensor. The superior gas sensing ability along with its low cost and the use of scalable electrospinning technique could make this system a promising one for the detection of gaseous NO₂.

Lanthanide type of cerium sulfide embedded carbon nitride composite modified electrode for potential electrochemical detection of sulfaguanidine

Environmental sustainability is threatened by the widespread exploitation and unfettered release of chemical pollutants that require immediate detection and eradication. An instantaneous quantification technique is essential to understand the physiological roles of the antibacterial drug sulfaguanidine (SGN) in biological systems. The present work features the green and environmentally benign synthesis of rare earth metal sulfide nanorods incorporated carbon nitrides sheets (Ce₂S₃@CNS) by deep eutectic solvent-based fabrication with remarkable electrochemical properties. The morphological and structural analyses of the prepared electrocatalyst were characterized using various techniques including SEM, XRD, XPS, and EIS. The heterojunction of regimented structures bids synergistic quantum confinement effects and refines charge carriers endorsing enormous active sites. Furthermore, the obtained Ce₂S₃@CNS/GCE possess an exceedingly lower limit of detection (0.0053 μM) and high sensitivity of 8.685 μA·μM^-1·cm^-2 with superior electrocatalytic action and virtuous stability for the detection of SGN. This modified electrode could afford linearity in the range 0.01-1131.5 μM measured at 0.95 V (vs. Ag/AgCl) correlated to the concentration of SGN. Examining the real samples with this advanced electrocatalyst would support its hands-on applications in everyday life. Development of such innovative architectures with fewer energy necessities and nominal by-products scripts the superiority in characteristic synthetic methodology following the guidelines of green chemistry.

Effective and reliable platform for nonenzymatic nanomolar-range quinol detection in water samples using ceria doped polypyrrole nanocomposite embedded on graphitic carbon nitride nanosheets

A glassy carbon electrode modification by a novel ternary nanocomposite of advantageously united ceria, polypyrrole, and graphitic carbon nitride (CeO₂/Ppy@g-C₃N₄) is reported here. It can be used to tailor the sensor surface for the electrochemical detection of nanomolar-level quinol (Qnl), a chemical widely used as a developing agent in photography and lithography, as a cosmetic, and as an antioxidant in rubber and food industries. The occupational exposure of Qnl may occur by inhalation or dermal contact, leading to lot of health hazards. The synthesized nanocomposite was characterized by various analytical techniques such as UV-Vis, Fourier transformed infrared (FTIR), X-ray powder diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, selected area electron diffraction, and elemental mapping analyses. The oxidation current of Qnl is linear to its concentration in the range of 0.01-260 μM and the lowest detection and quantification limit are found to be 1.5 nM and 0.004 μM, respectively, with a sensitivity of 283.33 μA mM^-1 cm^-2. The performance of the modified electrode was compared with those of high-performance liquid chromatography, which indicates that the proposed sensor can be used as an effective and reliable platform for nano-molar detection of Qnl in various environmental and biological fluids.

Aqueous solution photocatalytic synthesis of p-anisaldehyde by using graphite-like carbon nitride photocatalysts obtained via the hard-templating route

Graphite-like carbon nitride (GCN)-based materials were developed via the hard-templating route, using dicyandiamide as the GCN precursor and silica templates. That resulted in urchin-like GCN (GCN-UL), 3D ordered macroporous GCN (GCN-OM) and mesoporous GCN (GCN-MP). The introduction of silica templates during GCN synthesis produced physical defects on its surface, as confirmed by SEM analysis, increasing their specific surface area. A high amount of nitrogen vacancies is present in modified catalysts (revealed by XPS measurements), which can be related to an increase in the reactive sites available to catalyse redox reactions. The textural and morphological modifications induced in GCN an enhanced light absorption capacity and reduced electron/hole recombination rate, contributing to its improved photocatalytic performance. In the photocatalytic conversion of p-anisyl alcohol to p-anisaldehyde in deoxygenated aqueous solutions under UV-LED irradiation, the GCN-UL was the best photocatalyst reaching 60% yield at 64% conversion for p-anisaldehyde production after 240 min of reaction. Under oxygenated conditions (air), the process efficiency was increased to 79% yield at 92% conversion only after 90 min reaction. The GCN-based photocatalyst kept its performance when using visible-LED radiation under air atmosphere. Trapping of photogenerated holes and radicals by selective scavengers showed that under deoxygenated conditions, holes played the primary role in the p-anisaldehyde synthesis. Under oxygenated conditions, the process is governed by the effect of reactive oxygen species, namely superoxide radicals, with a significant contribution from holes.

Enhancing the Sensitivity of Nanoplasmonic Thin Films for Ethanol Vapor Detection

Nanoplasmonic thin films, composed of noble metal nanoparticles (gold) embedded in an oxide matrix, have been a subject of considerable interest for Localized Surface Plasmon Resonance (LSPR) sensing. Ethanol is one of the promising materials for fuel cells, and there is an urgent need of a new generation of safe optical sensors for its detection. In this work, we propose the development of sensitive plasmonic platforms to detect molecular analytes (ethanol) through changes of the LSPR band. The thin films were deposited by sputtering followed by a heat treatment to promote the growth of the gold nanoparticles. To enhance the sensitivity of the thin films and the signal-to-noise ratio (SNR) of the transmittance–LSPR sensing system, physical plasma etching was used, resulting in a six-fold increase of the exposed gold nanoparticle area. The transmittance signal at the LSPR peak position increased nine-fold after plasma treatment, and the quality of the signal increased six times (SNR up to 16.5). The optimized thin films seem to be promising candidates to be used for ethanol vapor detection. This conclusion is based not only on the current sensitivity response but also on its enhancement resulting from the optimization routines of thin films’ architectures, which are still under investigation.

Ambient Temperature NO Adsorber Derived from Pyrolysis of Co-MOF(ZIF-67)

Co-, Ni-, and Zn-containing MOFs are prepared and then pyrolyzed to generate materials for ambient temperature NO adsorption. Materials containing Co are much more efficient for NO adsorption than those containing Ni and Zn; therefore, Co is identified as the active phase. The best performing material studied here achieves 100% low concentration (10 ppm) NO adsorption for more than 15 h under a weight hourly space velocity of 120 000 mL g^-1 h^-1. Powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopies, along with scanning electron microscopy and TEM, are used to probe the physicochemical properties of the materials, particularly the Co active phase, and chemistries involved in NO adsorption-desorption. NO adsorbs on oxygen-covered Co nanoparticle surfaces in the form of nitrates and desorbs as NO at higher temperatures as a result of surface nitrate decomposition. NO storage capacity decreases gradually upon repeated NO adsorption-desorption cycles, likely because of Co₃O₄ formation during these processes.

Effect of the Functionalization of Porous Silicon/WO₃ Nanorods with Pd Nanoparticles and Their Enhanced NO₂-Sensing Performance at Room Temperature

The decoration of noble metal nanoparticles (NPs) on the surface of metal oxide semiconductors to enhance material characteristics and gas-sensing performance has recently attracted increasing attention from researchers worldwide. Here, we have synthesized porous silicon (PS)/WO₃ nanorods (NRs) functionalized with Pd NPs to enhance NO₂ gas-sensing performance. PS was first prepared using electrochemical methods and worked as a substrate. WO₃ NRs were synthesized by thermally oxidizing W film on the PS substrate. Pd NPs were decorated on the surface of WO₃ NRs via in-situ reduction of the Pd complex solution by using Pluronic P123 as the reducing agent. The gas-sensing characteristics were tested at different gas concentrations and different temperatures ranging from room temperature to 200 °C. Results revealed that, compared with bare PS/WO₃ NRs and Si/WO₃ NRs functionalized with Pd NPs, the Pd-decorated PS/WO₃ NRs exhibited higher and quicker responses to NO₂, with a detection concentration as low as 0.25 ppm and a maximum response at room temperature. The gas-sensing mechanism was also investigated and is discussed in detail. The high surface area to volume ratio of PS and the reaction-absorption mechanism can be explained the enhanced sensing performance.

Sugarcane juice derived carbon dot-graphitic carbon nitride composites for bisphenol A degradation under sunlight irradiation

Carbon dots (CDs) and graphitic carbon nitride (g-C3N4) composites (CD/g-C3N4) were successfully synthesized by a hydrothermal method using urea and sugarcane juice as starting materials. The chemical composition, morphological structure and optical properties of the composites and CDs were characterized using various spectroscopic techniques as well as transmission electron microscopy. X-ray photoelectron spectroscopy (XPS) results revealed new signals for carbonyl and carboxyl groups originating from the CDs in CD/g-C3N4 composites while X-ray diffraction (XRD) results showed distortion of the host matrix after incorporating CDs into g-C3N4. Both analyses signified the interaction between g-C3N4 and CDs. The photoluminescence (PL) analysis indicated that the presence of too many CDs will create trap states at the CD/g-C3N4 interface, decelerating the electron (e-) transport. However, the CD/g-C3N4(0.5) composite with the highest coverage of CDs still achieved the best bisphenol A (BPA) degradation rate at 3.87 times higher than that of g-C3N4. Hence, the charge separation efficiency should not be one of the main factors responsible for the enhancement of the photocatalytic activity of CD/g-C3N4. Instead, the light absorption capability was the dominant factor since the photoreactivity correlated well with the ultraviolet-visible diffuse reflectance spectra (UV-vis DRS) results. Although the CDs did not display upconversion photoluminescence (UCPL) properties, the π-conjugated CDs served as a photosensitizer (like organic dyes) to sensitize g-C3N4 and injected electrons to the conduction band (CB) of g-C3N4, resulting in the extended absorption spectrum from the visible to the near-infrared (NIR) region. This extended spectral absorption allows for the generation of more electrons for the enhancement of BPA degradation. It was determined that the reactive radical species responsible for the photocatalytic activity were the superoxide anion radical (O2•-) and holes (h+) after performing multiple scavenging tests.

The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO₂ Nanorods Array

Layered Eu-doped SnO₂ ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO₂ nanorods growth up, resulting in tenuous SnO₂ nanorods ordered arrays. The X-ray diffraction (XRD) revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases. The surface defects that were caused by the incorporation of Eu ions within the surface oxide matrix were observed by high-resolution transmission electron microscope (HRTEM). The results of the response properties of sensors based on the different levels of Eu-doped SnO₂ layered nanoarrays demonstrated that the 0.5 at % Eu-doped SnO₂ layered nanorods arrays exhibited an excellent sensing response to methanal at 278 °C. The reasons of the enhanced sensing performance were discussed from the complicated defect surface structure, the large specific surface area, and the excellent catalytic properties of Eu dopant.