Oxynitride Research Articles

Synthesis, characterization and photocatalytic activity of alginate based hybrid material for efficient degradation of organic pollutants under UV light and sunlight irradiation

This study reports the development of alginate based hybrid material (Alg/CuO-gC₃N₄) with copper oxide (CuO) and graphitic carbon nitride (gC₃N₄). The Alg/CuO-gC₃N₄ hydrogel bead was prepared by two step process is as follows: formation of CuO-gC₃N₄ by co-precipitation method and incorporation of CuO-gC₃N₄ in the calcium alginate (Alg) by ionotropic gelation method. The structural and morphological features of the Alg/CuO-gC₃N₄ was characterized using different techniques namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), UV Diffuse Reflectance spectroscopy (UV-DRS) and Scanning electron microscopy (SEM). The photocatalytic activity of the Alg/CuO-gC₃N₄ was extensively evaluated by degrading methylene blue (MB) under UV–vis and sunlight irradiation. The influence of various parameters like pollutant type, initial dye concentration, catalyst dosage, effect of pH, light intensity and reusability was investigated. The Alg/CuO-gC₃N₄ achieved a maximum degradation efficiency of 86.26 % and 85.15 % for MB at a dye concentration of 1 × 10−5 M under UV–vis and sunlight irradiation respectively, within 60 min using 0.3 wt% of catalyst dosage. The Alg/CuO-gC₃N₄ exhibited excellent stability and reusability over multiple cycles. Additionally, the incorporation of CuO-gC₃N₄ in alginate facilitates in reducing the bandgap (2.54 to 2.28 eV) for efficient charge separation, further enhancing the overall photocatalytic activity.

High tribological performance of quenched–tempered 40Cr steel treated by plasma oxynitriding

Alloy steel 40Cr was treated by plasma oxynitriding after quenching and tempering. The microstructures, mechanical properties, and tribological performances of plasma oxidized–nitrided layer at tempering temperatures of 500, 520, and 540 °C were investigated. The typical tempered sorbite structure was present when the 40Cr alloy steel was treated by quenching at 900 °C and tempering. A special structure of mixed oxide–nitride layer along with the veinlike nitride phase was formed after plasma oxynitriding. The surface hardness of the quenched–tempered 40Cr alloy steel was significantly improved. The quenched 40Cr alloy steel tempered at 520 °C exhibited the highest hardness of approximately 973 HV0.2 and the lowest wear rate of about 1.72 × 10−14 m3 N−1 m−1 than the samples tempered at 500 and 540 °C. The oxide and nitride phases inside the plasma oxidized–nitrided layer played important roles in the improvement of the surface mechanical properties and the tribological performance of the quenched–tempered alloy steel.

Auto-combustion synthesis and characterization of La2CrMnO6/g-C3N4 nanocomposites in the presence trimesic acid as organic fuel with enhanced photocatalytic activity towards removal of toxic contaminates

Constructing semiconductor materials based on layered graphitic carbon nitride (g-C3N4) and metal oxides can help in extending the lifetime of charge carriers and aid in resolving the low number of active sites on their surface for light-driven processes. Herein, we initially designed La2CrMnO6 nanostructures through trimesic acid-assisted auto-combustion route and subsequently, La2CrMnO6/g-C3N4 nanocomposites were prepared by ultrasonic-assisted co-precipitation method with improved UV-catalytic performance. The shape, size distribution and various properties of nano-sized products were measured via diverse description systems of microscopic and spectroscopic. The photocatalytic performances of the La2CrMnO6 nanoparticles and La2CrMnO6/g-C3N4 nanocomposites were compared by degradation of artificial dyes under the UV-light region. Besides, the impacts of dye type, diverse weight percentages of g-C3N4:La2CrMnO6 in composite, scavenger kind and dye solution concentration were studied on modifying ability of nano-catalyst utility. The outcomes manifested La2CrMnO6/g-C3N4 (80:20) nanocomposites have the greatest efficiency, where the highest MO decomposition of 80.98 % was achieved at 10 ppm within 90 min of irradiation. Moreover, the feasible mechanism of MO elimination by UV catalytic purpose was considered.

Radiant synergy: Illuminating methyl orange dye removal with g-C3N4/ZnO heterojunction photocatalyst

In this study, a robust hybrid heterojunction composite of g-C3N4/ZnO was successfully synthesized using a straightforward and cost-effective coprecipitation method. The resulting composite amalgamates the properties of graphitic carbon nitride (g-C3N4) and zinc oxide nanoparticles (ZnO NPs). Thorough characterization using techniques such as XRD, FT-IR, FE-SEM, HR-TEM, UV-DRS, EIS, PL, and EDX confirmed the structural and elemental composition of the catalyst. The challenge of using photons as the sole energy source for the activation of photocatalysts under ambient conditions was addressed. The photocatalytic potential of the hybrid heterojunctions was assessed by degrading the methyl orange (MO) dye under sunlight. The 10 wt% g-C3N4/ZnO composite exhibited effective suppression of charge recombination during photocatalytic degradation. Notably, the heterojunction 10 wt% g-C3N4/ZnO composite displayed remarkable photocatalytic performance, achieving a substantial 98 % degradation of MO within 90 min of solar irradiation, outperforming other materials. Moreover, the synthesized composites exhibited favorable attributes in terms of recyclability and mechanical stability, retaining their efficacy over five cycles. This substantiates their promising role as potential candidates for future photocatalyst applications. In essence, g-C3N4/ZnO heterojunction composites offer a robust solution for efficient and sustainable photocatalytic degradation of organic pollutants.

Tunable Phonon Polariton Hybridization in a Van der Waals Hetero-Bicrystal.

Phonon polaritons, the hybrid quasiparticles resulting from the coupling of photons and lattice vibrations, have gained significant attention in the field of layered van der Waals heterostructures. Particular interest has been paid to hetero-bicrystals composed of molybdenum oxide (MoO3) and hexagonal boron nitride (hBN), which feature polariton dispersion tailorable via avoided polariton mode crossings. In this work, the polariton eigenmodes in MoO3-hBN hetero-bicrystals self-assembled on ultrasmooth gold are systematically studied using synchrotron infrared nanospectroscopy. It is experimentally demonstrated that the spectral gap in bicrystal dispersion and corresponding regimes of negative refraction can be tuned by material layer thickness, and these results are quantitatively matched with a simple analytic model. Polaritonic cavity modes and polariton propagation along "forbidden" directions are also investigated in microscale bicrystals, which arise from the finite in-plane dimension of the synthesized MoO3 micro-ribbons. The findings shed light on the unique dispersion properties of polaritons in van der Waals heterostructures and pave the way for applications leveraging deeply sub-wavelength mid-infrared light-matter interactions.

Cement based nanofiltration membrane of porous boron nitride and graphene oxide for effective oil/water separation

The development of effective filters for crude oil/water separation presents a critical environmental challenge in the face of oil spills. Porous membrane separation stands as a vital technique for removing organic solvents, oils, and dyes from water. In this study, we designed and fabricated a nanofiltration membrane composed of graphene oxide (GO) and boron nitride (BN) incorporated into a cement-based matrix to enhance the selectivity and efficiency of unidirectional flux transportation. The integration of GO, with its rich functional groups, and BN, known for its hydrophobic properties, within the cement matrix, resulted in an improved water permeation rate. Moreover, the inclusion of BN flakes in the cement matrix significantly enhances its mechanical strength, reaching up to 15.93 MPa (∼35 % greater than pristine cement), establishing it as a robust nanofiltration membrane for simultaneous flux enhancement and water purification. This innovative filter demonstrated remarkable separation efficiency, achieving up to 99 % oil removal while allowing the passage of water. To gain a deeper understanding of our experimental findings, we conducted ab initio investigations into the adsorption behavior of water and oil components, including ethanethiol, thiophene, and toluene molecules, on h-BN, GO, and their defective structures (Stone-Wales defect). Our results affirm that porous h-BN and GO nanosheets, characterized by their high specific surface areas, exhibit remarkable sorption capabilities. This nanoengineered membrane showcases substantial adsorption capacity alongside physisorption characteristics suitable for recycling, thereby holding significant potential for the development of functional porous structural materials in the realm of high-performance, cost-effective, and environmentally sustainable water treatment solutions.

One-Step Electrodeposition of MnO2-Graphitic Carbon Nitride Composite Layer on Screen Printed Electrode for Electrocatalytic Dopamine Sensing

Electroanalysis using screen-printed electrodes offers a cost-effective, rapid, and on-site analyte quantification. Nevertheless, ensuring the necessary stability, sensitivity, and selectivity of SPE in order to perform precise ultra-low-level analyses is critical. The use of nano-structured materials for surface functionalization is one of the most prevalent strategy to augment the sensitivity and selectivity of sensors. However, the selection of the surface functionalization technique and material plays a crucial role. The present study outlines a single step electro-functionalization of the screen-printed sensor (SPE) with a carbon–metal oxide composite consisting of graphitic carbon nitride and manganese oxide (gCN.MnxOy). The electrodeposited gCN.MnO2 layer has been thoroughly analysed using spectroscopic, microscopic, and electrochemical techniques. As a test case, the electro-functionalized SPE was used to quantify dopamine by monitoring its electrocatalytic oxidation. Due to π-π interaction between the aromatic ring structures of the gCN and dopamine molecules, H-bonding, enhanced electroactive site, and facilitated charge transfer at the MnO2.gCN surface layer, the modified SPEexhibited a 15-fold higher peak current and a negative potential shift of 150 mV for DA oxidation. Being 44 times more sensitive, gCN.MnO2|SPE exhibited a detection limit of 10 nM compared to 5.36 µM for the unmodified electrode. As proof of application, the gCN.MnO2|SPE successfully estimated dopamine in pharmaceutical formulations, banana peel, and clinical samples namely saliva, urine and blood serum with an error of less than 9 %. We believe, the proposed modification protocol has the potential to create low-cost disposable functional interfaces that match the desirable properties of commercial products.

Superconducting single-photon detector integrated in DBR with optical microconnector for MM or SM fiber

This paper presents the development of a superconducting nanowire single-photon detector (SNSPD) integrated into a distributed Bragg reflector (DBR) with a design center wavelength of 830 nm and a bandwidth of 200 nm. This SNSPD is made of a superconducting niobium nitride (NbN) thin film that is produced using plasma-enhanced atomic layer deposition. The DBR is made of 15 alternating layers of silicon nitride and silicon oxide that are produced through plasma-enhanced chemical vapor deposition. The reflection efficiency of the mirror is 90% at a wavelength of 830 nm. For sufficient optical coupling, an optical micro-connector optimized for multimode or single-mode optical fibers with a diameter of 128 μm was formed using two-photon polymerization techniques. The niobium nitride film was deposited onto the DBR surface in-situ in two separate reactors connected by a vacuum transfer. The in-situ technique of deposition of a superconducting niobium nitride film and a DBR has allowed achieving a system detection efficiency of 90% at a wavelength of 830 nm and a dark count rate of 10 s−1 at a temperature of 2.5 K. Additionally, the detector jitter was 50 ps.

Experimental investigation on the effect of nano-enhanced phase change materials on the thermal performance of single slope solar still

Solar desalination is employed to create drinkable water from salt water. Using solar energy saves money and supplies clean, renewable fresh water. Nano-enhanced Phase change materials (NEPCM) and nano-enhanced absorption were utilized in this analysis to increase the capacity of solar desalination. Increased solar energy absorption makes anthracite content in saline water. CuO and AlN nanoparticles at 0.2 wt% and 0.4 wt% were combined in paraffin wax and injected into 12 copper pipes on the anthracite to boost the thermal characteristics of PCM. Copper pipes coated with dark paint containing scattered CuO nanoparticles to improve thermal conductivity. According to the findings, solar still production amplifies by 55.8 % and 49.5 %, respectively. Copper Oxide and Aluminium Nitride nanoparticles, each containing 0.2 wt%, lowered the melting temperature to 2.2ºCand 1.9ºC, respectively. It found that the CPL values of the Single slope solar still were 0.2₹/L and 8.26₹/L with the nano-enhanced PCM at 0.4 wt% CuO and AlN. The nano-coating also achieved a 5.7 % rise in the water production rate of the solar still.

A Comparative DFT Investigation of the Adsorption of Temozolomide Anticancer Drug over Beryllium Oxide and Boron Nitride Nanocarriers.

Herein, attempts were made to explore the adsorption prospective of beryllium oxide (Be12O12) and boron nitride (B12N12) nanocarriers toward the temozolomide (TMZ) anticancer drug. A systematic investigation of the TMZ adsorption over nanocarriers was performed by using quantum chemical density functional theory (DFT). The favorability of Be12O12 and B12N12 nanocarriers toward loading TMZ was investigated through A↔D configurations. Substantial energetic features of the proposed configurations were confirmed by negative adsorption (E ads) energy values of up to -30.47 and -26.94 kcal/mol for TMZ•••Be12O12 and •••B12N12 complexes within configuration A, respectively. As per SAPT results, the dominant contribution beyond the studied adsorptions was found for the electrostatic forces (E elst = -100.21 and -63.60 kcal/mol for TMZ•••B12N12 and •••Be12O12 complexes within configuration A, respectively). As a result of TMZ adsorption, changes in the energy of molecular orbitals followed by alterations in global reactivity descriptors were observed. Various intermolecular interactions within the studied complexes were assessed by QTAIM analysis. Notably, a favorable adsorption process was also observed under the effect of water with adsorption energy ( reaching -28.05 and -22.26 kcal/mol for TMZ•••B12N12 and •••Be12O12 complexes within configuration A, respectively. The drug adsorption efficiency of the studied nanocarriers was further examined by analyzing the IR and Raman spectra. From a sustained drug delivery point of view, the release pattern of TMZ from the nanocarrier surface was investigated by recovery time calculations. Additionally, the significant role of doping by heavy atoms (i.e., MgBe11O12 and AlB11N12) on the favorability of TMZ adsorption was investigated and compared to pure analogs (i.e., Be12O12 and B12N12). The obtained data from thermodynamic calculations highlighted that the adsorption process over pure and doped nanocarriers was spontaneous and exothermic. The emerging findings provide a theoretical base for future works related to nanocarrier applications in the drug delivery process, especially for the TMZ anticancer drug.

Synthesis Bi2O3/gC3N4 heterostructures: Investigation structural, morphological and photocatalytic activity towards methylene blue and rhodamine B

Waste from various dyes as a result of industrial development is an important source of pollutants for water resources; These wastes are frequently carcinogenic, mutagenic and toxic to aquatic life, so treating wastewater is vitally important. Photocatalytic purification is a popular method because it can break down dye molecules and change them into non-toxic, small and harmless species. Moreover, utilizing the power of sunlight, this technology holds significant promise for enabling environmentally friendly, sustainable, and economically viable technologies. The non-toxic polymeric photocatalyst graphitic carbon nitride (gC3N4) is an n-type semiconductor. Its facile and economical synthesis, effective band structure, and stability make it a popular option for photocatalytic investigations. It is crucial to develop nanocomposites to boost the capacity of materials for photocatalysis. The objective of this study is to fabricate nanocomposites of graphitic carbon nitride from thiourea, incorporating varying ratios of bismuth oxide through thermal condensation. The aim is to employ these composites for the catalytic degradation of Methylene Blue (MB) and Rhodamine B (Rh B) dyes. The synthesized samples' morphological and structural characteristics were studied. Their photocatalytic activity against methylene blue and rhodamine B dyes has also been reported. The Bi2O3/gC3N4 heterostructured samples were prepared considering bismuth nitrate and thiourea at weight ratios of 0.125:10, 0.25:10, and 0.5:10. In the study, the Bi2O3/gC3N4 heterostructured sample with the lowest bismuth doping rate was seen to have the highest photocatalytic degradation efficiency. A remarkable degradation rate, reaching 98.83 % within 70 min for MB and 98.59 % within 60 min for RhB dye was observed. The enhanced photocatalytic activities of the synthesized composite can be attributed to the synergistic effect of the heterostructure developed between graphitic carbon nitride and bismuth oxide. As a result, this study has shown promise that Bi2O3/gC3N4 composite photocatalysts can be an effective material for removing dyes.

Highly Sensitive Diethylamine Detection at Room Temperature Using g-C3N4 Nanosheets Decorated with CuO Hollow Polyhedral Structures.

Chemiresistive-based metal oxide semiconductor (MOS) gas sensors are widely used in gas sensing due to their advantageous properties. Graphitic carbon nitride (g-C3N4) and metal oxide heterostructure materials can improve charge transport properties, selectivity, and sensitivity in MOS gas sensor materials. Herein, for the first time, CuO hollow polyhedral structures (HPSs) were synthesized via a hydrothermal technique and annealed at different temperatures, with the 400 °C annealed (CuO-400 HPSs) demonstrating remarkable sensing capabilities for diethylamine (DEA) gas at room temperature (RT). The x-g-C3N4 nanosheets were decorated with CuO HPSs in varying amounts (x = 0.8, 1.8, 2.1, and 3.1 wt %) and then annealed at 400 °C for x-g-C3N4-CuO-400 hollow polyhedral heterostructures (HPHSs). Indeed, among the synthesized samples, the 1.8%-g-C3N4-CuO-400 HPHSs have a higher sensitivity to DEA (resistance change in gas (Rg) and air (Ra); Rg/Ra= 65 @ 20 ppm), a low detection limit (Rg/Ra= 6 @ 500 ppb), wide dynamic response (Rg/Ra= 190 @ 80 ppm), strong stability (30 days), and 21.6 times higher sensitivity than pure CuO at RT toward 20 ppm of DEA. The exceptional gas-sensing behavior can be attributed to various factors, including controlled annealing conditions that result in the formation of well-defined structures and greater porosity, efficient charge transfer properties resulting from an optimized ratio of g-C3N4 to CuO in HPHSs, an abundance of defects, unsaturated Cu sites, and synergistic effects. The study presents a universal strategy for generating sensitive and selective g-C3N4-based composite materials for low-temperature gas sensors.

Transient In situ DRIFTS Investigation of CO2 Hydrogenation to Methanol over Unsupported CuGa Catalysts

AbstractGallium oxide‐based catalysts are promising candidates for CO2 hydrogenation to methanol, whilst mechanistic understanding of the catalytic systems is not yet fully understood. Here, transient in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies of CO2 hydrogenation over the unsupported CuGa and CuGaN (with N doping) catalysts were conducted. The findings show that N doping could possibly promote the formation of surface Cu+ sites on the interface between Cu and Ga2O3, and hence increasing the selectivity to methanol. However, N doping prohibited the reduction of Ga2O3 to oxygen‐deficient Ga2O3‐x, which is unfavorable for CO2 conversion. Additionally, during DRIFTS the steady‐state isotope transient kinetic analysis (SSITKA) was performed (under H2/D2 isotopic switching conditions). The SSITKA results confirm that the Cu+‐bound formates were likely the key intermediates for methanol synthesis over the catalyst, and the N doping could also weak the interaction between CO* species and the catalyst surface, and thus facilitating the selectivity towards methanol rather than CO. Findings of the work show that the partial nitridation of the metal oxides could be the strategy to promote methanol synthesis selectivity.

Solar-powered photocatalysis in water purification: applications and commercialization challenges

Although heterogeneous photocatalysis has been recognized as a promising technology for decontaminating and disinfecting municipal and industrial wastewater over the last few decades, it has not yet successfully transitioned from laboratory-scale research to real-world applications. This limited progress is attributed to inherent physicochemical properties of most photocatalytic materials available, which exhibit reduced photoefficiency under visible light irradiation, along with multiple engineering considerations. This comprehensive review delves into the intricate dynamics of photocatalytic reactions kinetics, exploring several types of photocatalytic reactors and elucidating the significance of materials employed in photocatalytic wastewater treatment. This critical survey systematically examines the effectiveness of different materials such as titania, zinc oxide and graphitic carbon nitride which are commercially applied for different reactor systems. Understanding the role of these materials for photocatalytic reactions is essential to address the challenges associated with wastewater treatment. Furthermore, the discussion extends beyond the technical aspects to encompass the broader landscape of challenges hindering the commercialization and widespread adoption of photocatalytic technologies. By critically evaluating these challenges, the minireview aims to provide valuable insights for researchers, engineers, and policymakers seeking to advance and implement photocatalytic wastewater treatment on a broader scale. This synthesis of knowledge consolidates the current state of the field and outlines future prospects for overcoming barriers and optimizing the potential of photocatalytic processes in environmental remediation.

Визначення білків гострої фази в крові щурів після імплантації поліпропіленових хірургічних сіток із покриттям на основі танталу та його похідних

At present, more than 30 types of polypropylene surgical meshes are available in the world, but the statistics regarding the secondary inflammatory process after implantation still remain disappointing. Since polypropylene surgical meshes do not decompose well in the body, they can stimulate the surrounding tissuesto develop an inflammatory process that causes adhesions. For the past 50 years, tantalum has been successfully used to produce biocompatible medical implants in surgery, orthopedics, and dentistry. Its excellent anti-inflammatory and antibacterial properties have been repeatedly noted, indicating the possibility of its use as a coating for mesh implants. In order to better predict the outcome after implantation of biomedical materials, it is important to determine the content of acute phase proteins, namely C-reactive protein, haptoglobin and ceruloplasmin. The aim of the study is to determine the content of acute phase proteins, namely C-reactive protein, haptoglobin and ceruloplasmin in the blood of rats after implantation of surgical meshes coated on the basis of tantalum, tantalum oxide and tantalum nitride. Materials and methods. The experimental group included 40 male rats of the WAG population. With the help of surgical intervention, a polypropylene surgical mesh measuring 15x15 mm was implanted between the abdominal wall and various sections of the colon. 28 days after surgery, the experimental animals were decapitated by cervical dislocation. Blood samples were used to determine the content of C-reactive protein, the content of haptoglobin and the content of ceruloplasmin. Results and discussion. The content of C-reactive protein in the blood of rats was statistically 260 % higher in the experimental group implanted with uncoated surgical mesh and 228.8 % higher in the experimental group implanted with polypropylene surgical mesh with tantalum nitride coating in compared with the results in the group of intact animals. Haptoglobin content was statistically 110.5 % higher and ceruloplasmin was statistically 52.6 % higher in the uncoated surgical mesh group compared to the results of the intact animal group. We obtained similar results in the experimental group, which was implanted with a polypropylene surgical mesh with a coating based on tantalum nitride. The content of haptoglobin was 130 % higher and the content of ceruloplasmin was 50.6 % higher statistically compared to the results of the group of intact animals. The C-reactive protein content was 113.3 % and 95.5 % higher, respectively, in the groups implanted with polypropylene surgical meshes with a coating based on tantalum and tantalum oxide compared to the results in the group of intact animals. The content of haptoglobin in the tantalum-based coating group was 83.8 % higher and the content of ceruloplasmin was 32.6 % higher compared to the results obtained in the group of intact animals. In the tantalum oxide- based group, the haptoglobin content was 60.1 % higher and the ceruloplasmin content was 29.3 % higher compared to the results obtained in the intact animal group. Conclusion. Based on the results of the study, it was established that polypropylene surgical meshes coated with tantalum and tantalum oxide significantly reduce the inflammatory reaction compared to uncoated meshes and meshes coated with tantalum nitride. This is supported by lower levels of key inflammatory markers, indicating improved biocompatibility and anti-inflammatory effects of tantalum and tantalum oxide coatings.

Facile fabrication of 3D-α-Fe2O3@2D-g-C3N4 heterojunction composite materials: Effect of iron oxide loading on the electrochemical performance

Designing heterojunction nanocomposites is crucial for optimizing supercapacitor electrodes. This study addresses the challenge by introducing a facile synthesis method for creating 3D-α-Fe2O3@2D-g-C3N4 heterojunctions through a bulk carbon nitride-assisted hydrothermal process. During this process, the growth of ferric oxide particles coincides with the exfoliation and deposition of carbon nitride, leading to simultaneous structural changes in both iron oxide and carbon nitride phases. The resulting composite's properties strongly correlate with the iron oxide loading. Comprehensive characterization using XRD, FTIR, SEM-EDAX, XPS and TEM identified three distinct structures for α-Fe2O3/g-C3N4 composites based on iron oxide loading: low, medium, and high. The medium-loaded sample demonstrated superior electrochemical performance, attributed to better interfacial contact and the formation of 3D-Fe2O3@2D-g-C3N4 heterojunctions. This composite, with an optimized 22 wt% iron oxide loading, exhibited a maximum specific capacitance of 925.1 Fg−1 at 5 mVs−1 and 498.6 Fg−1 at 6 Ag−1 in charge-discharge analysis, with stable performance over 2000 cycles. Overall, this research presents an enhanced hydrothermal method for facile preparation of effective α-Fe2O3/g-C3N4 heterojunction materials.

Synergistic effect of ZnO/Ag2O@g-C3N4 based nanocomposites embedded in carrageenan matrix for dye degradation in water

This research achieved success by synthesizing innovative nanocomposite composed of zinc oxide (ZnO), graphitic carbon nitride (g-C3N4) and silver oxide (Ag2O) nanomaterials incorporated into a carrageenan matrix, thus creating an environmentally friendly and stable support structure. The synthesis process involved hydrothermal and chemical precipitation methods to create photocatalytic g-C3N4, ZnO, and Ag2O nanocomposites. The success is evident through the characterization results, which unveiled distinctive peaks corresponding to Zn–O (590-404 cm−1) and Ag–O (2072 cm−1) stretching in the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, conclusively confirming the successful synthesis of g-C3N4, ZnO, Ag2O, and their respective nanocomposites. Further validation through a scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDX) and elemental mapping affirmed the presence of Zn, O, Ag, C, and N. Additionally, transmission electron microscope (TEM) imaging unveiled the nanosheet morphology of g-C3N4, the nanorod structure of ZnO, and the spherical form of Ag2O nanomaterials. ZnO and Ag2O nanomaterials demonstrated a consistent 10–20 nm size range. To underscore their ability to harness visible light, the nanomaterials were excited at 380 nm, emitting visible light emission within the 400–450 nm range. The synthesized nanocomposites showcased outstanding adsorption and photocatalytic properties, achieving efficiency ranging from 80 % to 98 %, attributed to the synergistic interactions between the various components. These findings culminate in a confirmation of the research's success, validating the exceptional potential of these nanocomposites for various applications.

Nitrided copper-iron composite oxides derived from layered double hydroxides for enhanced carbon dioxide electroreduction to methane and formic acid

The reduction of carbon dioxide into valuable chemical products is a promising solution to address carbon balance and energy issues. Herein, amorphous nitrided copper-iron oxides are prepared by gas-phase nitriding of CuFe-layered double hydroxide precursors with urea as a nitrogen source. The obtained materials show high activity for CO2 electroreduction to methane and formic acid, achieving a total Faraday efficiency of 74.7% at −0.7 V vs. RHE and exhibiting continuous 10 h durability in the H-cell. The uniformly distributed Cu+ sites act as active sites by losing electrons to activate CO2. During the CO2 electroreduction, CO2 is converted to *COOH via proton-electron coupling; *COOH combines directly with a proton in solution to produce the HCOOH product; and the other part of *COOH undergoes a protonated dehydration process to form the *CHO intermediate, which dehydrates again to form CH4. This study provides a new approach for designing CO2 electroreduction catalysts.

A facile method for boosting the graphitic carbon nitride's photocatalytic activity based on 0D/2D S-scheme heterojunction nanocomposite architecture

Graphitic carbon nitride (g-C3N4) has received significant interest as a metal-free photocatalyst. The S-scheme photocatalytic system has great potential to improve the charge separation in semiconductor photocatalysts. In this study, we have fabricated non-toxic and low-cost photocatalytic nanocomposites of 0D/2D S-scheme heterojunction composed of iron oxide and graphitic carbon nitride by a facile method. The developed facile method provides a sustainable way with a high atom economy to further enhance the photocatalytic performance of exfoliated g-C3N4. The 0D-iron oxide/2D-C3N4 exhibited nearly 10 times better than bulk g-C3N4 and almost 60 % better than exfoliated g-C3N4 under simulated solar light irradiation. The experimental results demonstrated that the effective charge-carrier mechanism led to an improved generation of reactive oxygen species (ROSs), resulting in an impressive photocatalytic performance. A serial photocatalytic test was also conducted to understand photocatalytic reaction mechanisms with various scavengers.

Interface engineering of hierarchical flower-like N, P, O-doped NixPy self-supported electrodes for highly efficient water-to-hydrogen fuel/oxygen conversion

Rational construction of efficient bifunctional catalysts with robust catalytic activity and durability is significant for overall water splitting (conversion between water and hydrogen fuel/oxygen) using non-precious metal systems. In this work, the hierarchically porous N, P, O-doped transition metal phosphate in the Ni foam (NF) electrode (hollow flower-like NPO/NixPy@NF) was prepared through facile hydrothermal method coupled with phosphorization treatment. The hierarchical hollow flower-like NPO/NixPy@NF electrodes exhibited high bifunctional activity and stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solutions. The optimized electrode showed low overpotentials of 76 and 240 mV for HER and OER to reach a current density of 10 mA cm−2, respectively. Notably, the NPO/NixPy@NF electrode only required a low voltage of 1.99 V to reach the current densities of 100 mA cm−2 with long-term stability for overall water splitting using the NPO/NixPy@NF|| NPO/NixPy@NF cell, surpassing that of the Pt/C-RuO2 (2.24 V@ 100 mA cm−2). The good catalytic and battery performance should be attributed to i) the open hierarchical structure that enhanced the mass transfer; ii) a highly conductive substrate that accelerated the electron transfer; iii) the rich heterojunction and strong synergy between Ni2P and Ni5P4 that improved the catalytic kinetic; iv) the proper-thickness amorphous phosphorus oxide nitride (PON) shell that realized the stability. This work demonstrates a promising methodology for designing bifunctional transition metal phosphides with high performance for efficient water splitting.