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The recent increase in the use of graphene and its derivatives is due to their exceptional physicochemical, electrical, mechanical, and thermal properties as the industrial materials developed by involving graphene structures can fulfill future needs. In that view, the potential use of these graphene-containing nanomaterials in electronics applications has encouraged in-depth exploration of the electronic, conducting, and other functional properties. The protecting undifferentiated form of graphene has similarly been proposed for various applications, for example, as supercapacitors, photovoltaic and transparent conductors, touch screen points, optical limiters, optical frequency converters, and terahertz devices. The hybrid composite nanomaterials that undergo stimulus-induced optical and electrical changes are important for many new technologies based on switchable devices. As a two-dimensional smart electronic material, graphene has received widespread attention, and with that view, we aim to cover the various types of graphene oxide (GO)-based composites, linking their optical and electrical properties with their structural and morphological ones. We believe that the topics covered in this review can shed light on the development of high-yield GO-containing electronic materials, which can be fabricated as the field moves forward and makes more significant advances in smart optoelectronic devices.

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In this study, a natural resource—carbon dots—was used to synthesize green carbon quantum dots (CQDs) with high fluorescence. Specifically, the bottom-up method was used to prepare CQDs from Magnolia Grandiflora at various times (14, 16, 18, and 20 min) and under various conditions (900 – 1400 watts). Hydrogen Sulfide (H2S) was used to synthesize S doped-CQDs by adding in the optimum condition. The synthesized S doped-CQDs had a uniform size according to TEM analysis, along with an amorphous structure, water solubility containing hydroxyl and carboxyl groups, excitation light-dependent characteristics, and high photostability. In this research, S-doped-CQDs could detect Ni2+ in a rapid, sensitive, and highly selective manner with a detection limit of 0.5 μM – 10 μM by using Uv Vis methods. Moreover, in this study, S-doped-CQDs have been used in latent fingerprint detection, and it is shown more clearly under Uv-Lamp and has a bright blue fluorescence. This study used S doped-CQDs derived from natural resources as high-performance fluorescent probes for the detection of Ni2+ and latent fingerprints on nonporous surface material

Lithium ions-doped NaV6O15 thin films have been prepared using a simple low temperature liquid phase deposition method and subsequent annealing process. X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), and photoelectron spectroscopy (XPS) have been used to study the structural and physicochemical characteristics of the NaV6O15 film. The films were grown on the FTO conductive glass and used directly as an electrode of sodium ion batteries. The prepared lithium ions-doped NaV6O15 thin film electrodes showed an excellent cycling stability and discharge capacity, which may be attributed to the stability of the Li+ embedded into the gap between the V–O layers to maintain the structure and its stable β-phase structure transformed after the first cycle. The cycling stability greatly improved with increasing annealing temperature, while the discharge capacity decreased. The capacities of the film electrodes annealed at 400 °C and 450 °C maintained above 97% after 100 cycles. The lithium-doped NaV6O15 underwent a phase transition during the first charge/discharge cycle. The new transformed phase has perfect crystal structure stability undergoing insertion and deinsertion of Na+. Therefore, the lithium-doped NaV6O15 thin film possesses good cycling stability and is expected to be a promising thin film cathode for sodium-ion batteries.

In this research, a novel LaCdSe-GO-TiO2 (LCS-G-T) has been synthesized by utilizing a high powersonic method under controlled condition. From the structural morphology, it is apparent that the composite is a good example of size control and low-cost synthesis with an ultrasound and scavenger effect. The synthesized LaCdSe-GO-TiO2 (LCS-G-T) composite has given a good efficiency for photocatalytic water splitting for hydrogen evolution. The implementation of high ultrasonic power has increased, the surface area decreased the particle size, due to the collapse by micro-bubbles occurred and formation of crystal enhancement. Different characterizations have been carried out for “as-prepared” composites, such as X-ray diffraction (XRD) for checking the crystallinity, scanning electron microscopy (SEM) for structural morphology, energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectra (DRS), and photoluminescence (PL) spectra, and a standard three-electrode system has been used in a cyclic voltammetry test. The LaCdSe-GO-TiO2 has exposed a good photocatalytic activity in the presence and absence of several scavengers. Moreover, the applied high powersonic for hydrogen production can significantly influence the photocatalytic activity of LaCdSe-G-T. The implemented high powersonic produces electric field bridge and helps the conversion of electron from photon.

We fabricated a novel nanocomposite composed of graphene-La2CrFeW6 perovskite compounds with an organic-inorganic counter electrode based on CdSe, gallic acid, urea and sulfate in dye-sensitized solar cells (DSSCs) by a simple hydrothermal technique. The nanocomposite shows an excellent electro–catalytic activity with low charge-transfer resistance, due to the synergetic catalytic effects of the graphene sheets and La2CrFeW6 perovskite with organic-inorganic materials. The special structure of this nanocomposite also improves the active sites for reduction of triiodide ions on the counter electrodes. The photo-conversion efficiency of the DSSC fabricated using a gallic-based counter electrode reached a higher value of 10.40% under standard illumination (1 sun, 100 mW cm−2, AM 1.5), as compared to the traditional Pt electrode (7.49%). The graphene-La2CrFeW6 fabricated with an organic-inorganic based CE was also found to be more efficient than those reported in previous works, in which graphene, produced by various methods, was used as a CE material. Therefore, the present nanocomposite is considered an environmentally friendly, low-cost, and highly efficient CE material for DSSCs.

This study aimed to synthesize dimethylglyoxime (DMG) (N-source)-doped graphene quantum dots (N-GQDs) via simultaneous pyrolysis of citric acid and 1.0% (w/v) DMG. The maximum excitation wavelength (λmax, ex = 380 nm) of the N-GQD solution (49% quantum yield (QY)) was a red shift with respect to that of bare GQDs (λmax, ex = 365 nm) (46% QY); at the same maximum emission wavelength (λmax, em = 460 nm), their resonance light scattering (RLS) intensity peak was observed at λmax, ex/em = 530/533 nm. FTIR, X-ray photoelectron spectroscopy, XRD, energy-dispersive X-ray spectroscopy, and transmission electron microscopy analyses were performed to examine the synthesized materials. The selective and sensitive detection of Ni2+ using the RLS intensity was performed at 533 nm under the optimum conditions consisting of both 25 mg L-1 N-GQDs and 2.5 mg L-1 DMG in the ammonium buffer solution of pH 9.0. The linearity of Ni2+ was 50.0-200.0 μg L-1 with a regression line, y = 5.031x - 190.4 (r 2 = 0.9948). The limit of detection (LOD) and the limit of quantitation (LOQ) were determined to be 20.0 and 60.0 μg L-1, respectively. The method precision expressed as % RSDs was 4.90 for intraday (n = 3 × 3) and 7.65 for interday (n = 5 × 3). This developed method afforded good recoveries of Ni2+ in a range of 85-108% when spiked with real water samples. Overall, this innovative method illustrated the identification and detection of Ni2+ as a DMG complex with N-GQDs, and the detection was highly sensitive and selective.

In this work, we synthesized a mesoporous BiZnSbV-G-SiO2 electrode-based sensor to detect microalbumin in urine, due to graphene based sensor system has a high electrocatalytic movement, electrical conductivity, abundance, and low cost. The synergistic effects of BiZnSbV-G-SiO2 nanocomposites advanced the electrochemical reaction and the affectability of the sensor. The synthesized active materials were characterized with surface morphology techniques, electron behavior controlling spectroscopy and electrochemical performance instrument, individually. Especially, chronoamperometric electrochemical evaluation system was used for the quantitative detection of microalbumin. We did electrochemical evaluations with a few possible compounds that regularly appear in urine (ascorbic acid, uric acid, glucose), which showed the good sensitivity and selectivity for the microalbumin detection. Under ideal conditions, the sensor can distinguish urinary microalbumin in a wide straight run from 0.01 to 0.1 μl with a location constraint of 0.01 μl. The excellent sensing performance of the mesoporous BiZnSbV-G-SiO2 active material was confirmed by analyzing microalbumin obtained from urine. The biosensor proposed here is specified in terms of simplification, low-cost, quick response, and precise screening for the microalbuminuria detection. This approach gives a promising stage for creating clinical point-of-care demonstrative applications. Additionally, the manufactured sensor had good selectivity, great reproducibility, great soundness, and good recuperation, which showed potential for applications in the clinical field.

Quaternary nanorod-type BaInSbSe5 semiconductor combined graphene-based conducting polymer (PPy) (BaInSbSe5-G-PPy, BNSGP) nanocomposites were prepared using a facile hydrothermal method. BNSGP nanocomposites were used to make up gas sensors to detect H2O2 and H2S at standard temperature condition. Morphologies, shape, and structures of BNSGP were specified by X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray elemental analyzer (EDX), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) technique, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). When examined with H2O2 and H2S concentrations as low as 10 ppb, the gas sensor using BNSGP nanocomposites showed a good reactivity and sensitivity of 1.25 V/K with real-time response/recovery effects of 234 and 76 s, respectively. It also showed a conspicuously high selectivity for H2O2 and H2S. However, it only showed insignificant response to any other reactance gases such as HCl, CH3OH, and C2H5OH. Its performance as a H2O2 and H2S sensor was estimated by CV meter (cyclic voltammeter). The fabricated sensor for H2O2 and H2S showed an extensive linear selectivity from 300 to 90 ppm with a low detection range of 300 ppm.

Herein, a novel visible-light-responsive g-C3N4/diatomite/MnO2 composite was successfully fabricated through a simple redox reaction method. The structure and morphology of the sample are mainly characterized by X-ray diffraction (XRD), photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet–visible spectroscopy (UV–Vis). In this paper, the photo-catalytic activity of the sample was evaluated by degradation RhB under visible-light irradiation. The results shown that, compared with g-C3N4/diatomite composite, MnO2, g-C3N4, diatomite, the prepared g-C3N4/diatomite/2.5%MnO2 composite exhibits better photo-catalytic activity and stability. At the same time, the effect of different MnO2 additions on the photo-catalytic activity of the composite material was further analyzed. The results indicated that the g-C3N4/MnO2/diatomite composites exhibit highest photo-catalytic activity when the adding amount of MnO2 reached 2.5%. The degradation rate of the g-C3N4/diatomite/2.5%MnO2 is 93% after recycling for three times, showing good stability and reusability. Moreover, the mechanism of catalytic performance enhancement also has been discussed.

This paper reports the synthesis of various molar concentrations of manganese (Mn)-doped Ultra-High Surface area Activated Carbon (USAC) additives and their efficient use as cathode materials for supercapacitors. We synthesized the nanoparticles via a novel and facile dip-coating process and characterized them in detail by various analytical techniques. The SEM, EDAX, and XPS results showed that the Mn ions were successfully substituted on the USAC additives’ layered structure without any structural changes. The long cyclic stability of the as-prepared Mn-doped USAC additives was tested as a cathode material for supercapacitors at different current densities. The detailed experimental results showed that the Mn dopant content crucially determines the electrochemical performances of the USAC additives. Electrochemical measurements showed that the MnCEP-S600HTT with 0.10 mol% molar concentration of Mn dopant gives the best cycling performances. It delivers a discharge capacity of 262.9 mAh g−1 after 100 cycles. Further increasing the current density to 1000 mA g−1 allowed it to still maintain 253.6 mAh g−1 after 200 cycles. We confirmed that the structure of Mn-doped USAC additives is an important pole to improve the structural stability and electrochemical properties.

To solve the common problems of concrete preparation in low-temperature environments, calcium formate (C2H2O4Ca), anhydrous sodium sulfate (Na2SO4), triethanolamine (C6H15O3N), calcium bromide (CaBr2), and triisopropanolamine (C9H21NO3) are selected as early strength agents and mixed with C40 concrete in different dosages under low-temperature environments of 5 oC and 10 oC to develop a high-efficiency low-temperature compound early strength agent based on the effect of single-doped early strength agents. The effects of the compound early strength agent on the early strength of the concrete, the cement paste setting time, and cement fluidity at 5 oC and 10 oC are investigated, and the corresponding reaction mechanism is discussed from the perspective of micro-products. The best compound early strength agent ratio is found to be 2% of calcium formate + 0.08 % of TEA (C6H15O3N). The compound early strength agent effectively promotes the formation of hydration products, such as Ca(OH)2 and C-S-H gel. In comparison with the control group, the strength of the concrete cured for 18 h, 1 d, 3 d, and 7 d under simulated natural conditions at 5 oC increases by 700%, 540%, 11.4 % and 10 %, respectively, whereas at 10 oC, the corresponding values are 991%, 400%, 19.6 % and 11 %, respectively. The strength of the concrete at each age is close to the normal temperature standard of the curing strength. The addition of the compound early strength agent causes a reduction in cement fluidity and initial and final setting times, and also yields a good effect on the porosity of the early concrete.

It is profoundly appealing to build a common enzyme-free sensor for detection of glucose. We effectively synthesized a uniform and mesoporous BiZnSbV-G-SiO2 (BZSVGS) quaternary nanocomposite by electrodeposition on a Ni foam substrate. This BiZnSbV-G-SiO2@NF composite terminal has been used as an electrocatalyst for coordinated oxidation of glucose, in this manner acting as a high-performance non-enzymatic glucose sensor. Coordinated electrochemical estimation with the as-arranged anodes in PBS and urea showed that the BiZnSbV-G-SiO2 nanocomposite has a great electrocatalytic movement toward glucose oxidation in a neutral medium and a wide straight reaction from 0.06 to 0.1 μmol/L, a low detection constraint of 0.06 μmol/L (S/N = 3) at a low connected potential of + 0.20 V vs Ag/AgCl. This ponder moreover highlights the effect of diminishing anion electronegativity on upgrading the electrocatalytic proficiency by bringing down the potential required for glucose oxidation and long-term steadiness together with a brief reaction time of roughly 4 s highlights the promising execution of the BiZnSbV-G-SiO2@NF anode for non-enzymatic glucose detection with high accuracy and unwavering quality. Besides, it can be used for glucose location in human blood serum, promising its application toward assurance of glucose in genuine tests.

In this investigation, 3D shaped BiVO4-GO composites have been set up with various proportions of BiVO4 by an altered hydrothermal strategy. This example is described by X-ray diffraction (XRD), Scanning electron microscopy (SEM), FT-IR, UV–Vis diffuse reflectance spectra (DRS), Raman spectroscopy, transmission electron microscopy (TEM) procedures and UV–Vis spectroscopy. BiVO4 could cover well on the outside of graphene sheets. BiVO4-GO composites with a reasonable expansion measure of BiVO4 indicated higher photocatalytic movement than plain BiVO4 toward fluid stage corruption of methylene blue (MB), texbrite BAC-L and texbrite NFW-L under obvious light illumination.

The potential application of MoS2 as a potential H2 precipitation photocatalyst has received widespread attention and is considered a promising alternative to precious metal cocatalysts due to its richness and low cost. However, the catalytic active center of MoS2 is only along the edge of the MoS2 layer. Both theoretical and experimental studies have shown that defect engineering can increase the active site of MoS2 and has superior activity in catalytic reactions. Therefore, this review describes the nature, defect types, and preparation of defective MoS2. Due to the recombination of MoS2 and semiconductor has specific interface characteristics, Schottky heterojunctions can provide accelerated charge separation and lower Schottky barriers for photocatalytic applications, they are effective photocatalysts. Therefore, the preparation of the defect MoS2-supported semiconductor photocatalyst and its application in the photocatalytic water splitting reaction are also introduced. This article’s profound understanding of defects can consolidate basic photocatalysis theory and provide new insights for the rational design of satisfactory defect engineering photocatalytic materials.

Hydroxyapatite (HAP) is the naturally occurring mineral form of calcium apatite and the most studied material as a bone substituent. Considering HAP's inherent properties, this study explored changes in HAP's characteristics from doping with other metals such as Fe. To form pure HAP and Fe-HAP with different amounts of Fe, we used the hydrothermal approach, and the composites that formed were thoroughly analyzed for their crystallinity, surface bonding, morphology, magnetic behavior, mechanical strength, biocompatibility, hemocompatibility, and in vitro cytotoxicity. The powder XRD studies confirmed the samples' crystallinity, and the lowest crystalline size was 19.7 nm in 10Fe-HAP. The FTIR analysis confirmed the formation of HAP by the hydroxyl, phosphate, and carbonate groups. The FESEM demonstrated that the morphology of the pure HAP was rod-shaped, which transformed into spheres after Fe doping. The EDS analysis confirmed the successful formation of HAP and Fe-HAP composites. The magnetic studies indicated the diamagnetic behavior of the pure HAP, while the Fe-doped HAPs had a superparamagnetic nature with saturation magnetizations (Ms) of 2Fe-HAP, 4Fe-HAP, and 10Fe-HAP at 0.0062, 0.0092, and 0.029 emu/g respectively. Assessment of the mechanical properties, biocompatibility, hemocompatibility, and cytotoxicity indicated that the Fe-doped HAPs were superior to the pure HAP, and among the Fe-HAPs, the 10Fe-HAP) had the highest amount of Fe and the best characteristics. The studies also indicated that Ca2+ interactions influenced the cells via HAP doping with that of Fe, equally increasing the physicochemical and biological properties.

In this study, we present an electrochemical investigation of a ternary mesoporous metal oxide (ZrO2, SiO2 and In2O3) modified graphene composite for non-enzymatic glucose, ascorbic acid, and albumin detection in urine at physiological pH. Synergetic property of ZrO2–Ag–G–SiO2 and In2O3–G–SiO2 were investigated via cyclic voltammetry (CV) using FTO glass and copper-foil electrodes with no prerequisite of solid antacid expansion. The mesoporous ZrO2–Ag–G–SiO2 and In2O3–G–SiO2 composites were synthesized and characterized using XRD, SEM, TEM, Raman spectroscopy, XPS, DRS, BET, and photocurrent measurements. Upon increasing the glucose concentration from 0 to 3 mM, CV results indicated two anodic peaks at +0.18 V and +0.42 V versus Ag/AgCl, corresponding to Zr3+ and Zr4+, respectively, considering the presence of glucose in urine. Moreover, the effects of high surface area In2O3–G–SiO2 were observed upon the examination of ZrO2–Ag–G–SiO2. In2O3–G–SiO2 demonstrated a decent electrochemical pattern in glucose, ascorbic acid, and albumin sensing. Nevertheless, insignificant synergistic effects were observed in In2O3-G, ZrO2-G, and ZrO2–G–SiO2. In2O3–G–SiO2 performed well under a wide range of electrolytes and urine, and showed no activity toward uric acid, suggesting potential for biodetection in urine.

While the mold that is blue-green Penicillium italicum is one of the most serious post-harvest plant infections, compromising the integrity of citrus and many other crops during storage and transportation, there is as yet no sensor for its detection on-site, or in the field. For the first time, we present the development of a novel CaMn4O8–G–SiO2 (CaMnGS) sensor to detect the presence of Penicillium italicum mold. CaMnGS was synthesized using a self-assembly technique in this study. CaMnGS sample demonstrated outstanding stability, high selectivity, and notable characteristics for Penicillium italicum fungus detection. For Penicillium italicum fungus sensing, the CaMnGS displayed a large linear range of (50–100) μL, and a low detection limit of 0.50 μL. Significantly, the CaMnGS sensor was capable of swiftly detecting the Penicillium italicum fungus in wastewater. The CaMnGS generated had no effect on cell survival and had tremendous potential for Penicillium italicum fungal sensing. The mesoporous CaMnGS sensor may also detect the presence or absence of the fungus Penicillium italicum. This method might be used to identify the fungus Penicillium italicum. This is also the first attempt to discuss the fabrication of an electrochemical sensor employing a mesoporous CaMnGS nanoparticle composite as a platform for the selective detection of Penicillium italicum.

A facile microwave assisted solvothermal process is designed for fabricating SnS nanoparticles decorated on graphene nanosheet, which used as visible light driven photocatalyst. Some typical characterization techniques such as XRD, FT-IR, SEM with EDX analysis, and TEM and BET analysis are used to analyse the physical characteristics of as-prepared samples. Spherical SnS nanoparticles are uniformly dispersed on the surface of graphene nanosheet due to ammonia, which can prevent the aggregation of graphene oxide. Meanwhile, microwave radiation provides fast energy that promotes the formation of spherical SnS nanoparticles within a short time. The visible light photocatalytic activity of as-prepared SnS-GR nanocomposites is analysed through photodegradation efficiency of methylene blue with high concentration. According to the higher photocatalytic property, the as-prepared SnS-GR nanocomposites can be expected to be an efficient visible light driven photocatalyst. After five cycles for decolorization, the rate decreases from 87 % to 78 % (about 9 %). It is obvious that the photocatalytic activity of SnS-GR nanocomposite has good repeatability.

For the efficient evolution of hydrogen, we designed a 3D quaternary BaCuZnS-graphene-TiO2 (BCZS-G-T) composite by an ultrasonic method. Herein, we prepared a quaternary material to minimize the bandgap energy and size. We characterized the “as-prepared” composites by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The high hydrogen evolution was attributed to the 3D quaternary BCZS-G-T composite with small bandgap energy because of its high photoelectron recombination properties. In addition, we demonstrated the combination effects with photocatalytic and sonocatalytic treatments with a scavenger. This work highlights the potential application of quaternary graphene-based composites in the field of energy conversion.

In the present study, electrochemical sensing for urea was proposed utilizing graphene-based quaternary nanocomposites YInWO4-G-SiO2 (YIWGS). These YIWGS nanocomposites were utilized due to their exceptionally delicate determination of urea with the lowest detection limit (0.01 mM). These YIWGS composites were developed through a simple self-assembly method. From physical characterization, we found that the YIWGS composites are crystalline in nature (powdered X-ray diffraction), and Fourier transform infrared (FTIR) spectroscopy analysis provided the surface functionality and bonding. Scanning electron microscopy (SEM) studies indicated the morphology characteristics of the as-synthesized composites and the high-resolution transmission electron microscopy (HRTEM) image supported the formation of cubic or hexagonal morphology of the YIW nanocomposites. The YIWGS sensor showed a great electroanalytical sensing performance of 0.07 mM urea with a sensitivity of 0.06 mA cm-2, an expansive linear range of 0.7-1.5 mM with a linear response (R2 1/4 0.99), and an eminent reaction time of around 2 s. It also displayed a good linear response toward urea with negligible interferences from normal coinciding species in urine samples.

Polylactic acid (PLA), although has many interesting physicochemical characteristics, the strong hydrophobicity and a lack of antibacterial activity restricting its widespread application in the medical sector. In a view of addressing some of the limitations of PLA, the current study aimed to test the antibacterial efficacy of active metal-doped bioceramic/PLA composite formed by the fused deposition manufacturing (FDM) technique. For the testing, we prepared polyvinyl alcohol (PVA) bound silver-hydroxyapatite (Ag-HAp) composite and further applied as a low-temperature coating onto the PLA scaffold designed for the appropriate cell development, differentiation, and bio-mineral establishment. From the analysis, we revealed that the larger surface area of three-dimensional (3D) printed composite material having the matrix porosity makes it a perfect biocompatible material with no loss to its mechanical potency. The HAp/PLA and Ag-HAp/PLA composites were tested for the hemocompatibility, and antibacterial activity (gram-positive and gram-negative bacteria). Further, the mechanical property of the Ag-HAp/PLA scaffold was tested. The results demonstrated that the Ag-HAp/PLA composite offers the biocompatibility and antibacterial ability and therefore can serve as the potential bone implant material. (C) 2020 The Author(s). Published by Elsevier B.V.

Reducing CO2 into high value fuels and chemicals is considered a great challenge in the 21st century. Efficiently activating CO2 will lead to an important way to utilize it as a resource. This article reviews the latest progress of g-C3N4 based catalysts for CO2 reduction. The different synthetic methods of g-C3N4 are briefly discussed. Article mainly introduces methods of g-C3N4 shape control, element doping, and use of oxide compounds to modify g-C3N4. Modified g-C3N4 has more reactive sites, which can significantly reduce the probability of photogenerated electron hole recombination and improve the performance of photocatalytic CO2 reduction. Considering the literature, the hydrothermal method is widely used because of its simple equipment and process and easy control of reaction conditions. It is foreseeable that hydrothermal technology will continue to innovate and usher in a new period of development. Finally, the prospect of a future reduction of CO2 by g-C3N4-based catalysts is predicted.

In this work, Ag3PO4/In2S3 nanocomposites with low loading of In2S3 (5-15 wt %) are fabricated by two step chemical precipitation approach. The microstructure, composition and improved photoelectrochemical properties of the asprepared composites are studied by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photocurrent density, EIS and amperometric i-t curve analysis. It is found that most of In2S3 nanoparticles are deposited on the surfaces of Ag3PO4. The as-prepared Ag3PO4/ In2S3 composite (10 wt%) is selected and investigated by SEM and TEM, which exhibits special morphology consisting of lager size substrate (Ag3PO4), particles and some nanosheets (In2S3). The introduction of In2S3 is effective at improving the charge separation and transfer efficiency of Ag3PO4/In2S3, resulting in an enhancement of photoelectric behavior. The origin of the enhanced photoelectrochemical activity of the In2S3-modified Ag3PO4 may be due to the improved charge separation, photocurrent stability and oriented electrons transport pathways in environment and energy applications.

This research focuses on the preparation of amino-functionalized magnetic graphene oxide nanocomposite (Fe3O4–GO–NH2), which increases the pre-concentration efficiency of Congo red residue in water samples. Their characterizations by FT-IR, SEM, EDX, and VSM were carried out in line with the magnetic property. The magnetic adsorbent was mainly used for the pre-concentration of anionic dye under optimized conditions of ultrasound-assisted magnetic dispersive solid-phase microextraction (UA-MDSPME). Typically, pre-concentration optimization conditions such as the pH of the solution, sorbent amount, power and sonication time, type of eluting solvent and its concentration were precisely investigated before the determination by UV–visible spectrophotometry. The analytical performance of the UA-MDSPE method was validated and found to have a linear range of 1.0–25.0 mg L−1 with R2 > 0.999. The limits of detection and quantification were 4.3 µg L−1 and 14.4 µg L−1, respectively. The precision of the method calculated from the slope of the calibration curve (%RSD, n = 3 × 3) for intra-day and inter-day analyses was 3.23 and 4.74, respectively. The extraction of Congo red dye from real water samples (drinking water, swamp water, and tap water) ranged from 90.65 to 105.8%. The enrichment factor of the developed procedure was averaged to 32.4 folds, ensuring the determination of trace amounts of residual dye in the water samples. It is, therefore, concluded that the magnetic adsorbent is an efficient method for the pre-concentration of hazardous dye from aqueous solution.

Photocatalytic CO2 reduction into hydrocarbon fuels over photocatalysts has hypothetical and reasonably developed into a trendy exploration topic. In this study, the progress of the quaternary nanocomposite containing a graphene-based catalyst was reported; this was fabricated using the hydrothermal technique. The analysis of physical characteristics of the nanocomposite confirmed the interaction between all parts. The quaternary nanocomposite containing the graphene-based catalyst was utilized for carbon dioxide reduction to methanol (CH3OH) under light irradiation. Titanium dioxide (TiO2) and the quaternary nanocomposite of AgCuInS2 were monotonously spread on the graphene exterior. This nanomaterial showed superior activity compared with TiO2 and the binary composite for CO2 conversion, and the obtained result indicates that the synthesized ternary composite enhaces the properties of the photocatalyst in the reduction process.

Here, we reported an innovative and electrochemical biosensor for the rapid detection of Escherichia coli O157:H7. We fabricated the mesoporous ZrO2-Ag-G-SiO2 (ZAGS) and In2O3-G-SiO2 (IGS) sensors,...

Polyaniline/Bismuth Vanadate/Graphene Oxide (PANI-BiVO4-GO) or BGPA composite was prepared by sonochemical deposition of bismuth vanadate-graphene oxide (BiVO4) nanoparticles on the surface of poly...

Herein we report on various surface morphological characteristics of the synthesized cobalt oxide (Co3O4) nanostructures obtained by means of facile one-step hydrothermal method for oxygen reduction reaction (ORR). The synthesized nanostructures of Co3O4 were adequately characterized by field emission scanning electron microscopy (FESEM) fitted with Energy-dispersive X-ray spectroscopy (EDX) elemental mapping, X-ray diffraction (XRD) and Raman techniques. The electrochemical studies were carried out to analyse the performance of as-synthesized catalysts for ORR by cyclic voltammetry (CV), and chronoamperometric (CA) techniques. A higher electrocatalytic response was observed for Co3O4 nanocubes compared with all the other controlled electrodes by CV with a current density of 0.69 mA/cm2 at a potential value of −0.46 V. The as-synthesized material showed adequate tolerance against methanol observed by CV in the presence of 0.5 M methanol, and good stability when compared with commercial Pt/C catalyst using the CA technique.

In this study, we demonstrate the fabrication and characterization of a new quaternary semiconductor nanocomposite of LiCuMo2O11/graphene oxide/polypyrrole (LCMGP) via a hydrothermal method and tes...

Graphene-based nanocomposites are usable as flexible transparent displays for electronic devices. However, the power conversions of graphene-based nanocomposites are more efficient than that of indium tin oxide. This outlook property can alternative for graphene-based materials in solar cells. The strength of graphene is due its ability to enable various components in existing solar cells, leading to the overall improvement in power conversion efficiency. Graphene can act as an electron acceptor and intermediate layer in tandem solar cells. Depending on the properties of graphene and graphene-based material, researchers have modified the structure where the π-electron variety, donor–acceptor and conformation can be tuned to create a novel type of light-reaping materials.

We successfully prepared multiple gas sensing devices comprising of a thin-film sensor made with mesoporous silica combined In2O3-graphene semiconductor nanocomposite for sensing CO2, O2, and NH3. We demonstrated that our sensor had high selectivity for CO2 by recognizing O2 and NH3 in the vapor stage with accurate transformation into electrical signals in devices. The mesoporous semiconducting In2O3–GO–SiO2-10% (IGS10) sensor showed quick response/recovery times for detecting gases, including CO2, O2, and NH3. Compared to In2O3, In2O3–GO (IG), and In2O3–GO–SiO2-20% (IGS20), the mesoporous IGS10 showed superior gas sensing ability due to the implied optimum ratio of the synthesized sample. Finally, we proved a facile, low-cost route to attain the multiple gas sensing devices with the potential for vast application.

In this work, a carbon-doped carbon nitride photocatalyst is successfully synthesized through a simple centrifugal spinning method after heat treatment. The morphology and properties of the prepared photo catalyst are characterized by Xray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis spectrophotometer (UV-vis), and specific surface area. The results show that the band gap of the prepared sample, g-CN-10 is 2.1 eV, is significantly lower than that of pure carbon nitride, 2.7 eV. As the amount of cotton candy increased, the absorption capacity of the prepared catalyst for visible light is significantly enhanced. In addition, the degradation efficiency of Rhodamine B (RhB) by sample g-CN-10 is 98.8 % over 2h, which is twice that value of pure carbon nitride. The enhancement of photocatalytic ability is attributed to the increase of specific surface area after the carbon doping modifies carbon nitride. A possible photocatalytic degradation mechanism of carbon-doped carbon nitride is also suggested.

The goal of this study was to analyse the impact of a combination of a sub-active material (KMnO4) with surface modification to the activated carbon surface for enhanced cathode performance. Activated carbon with ultra-specific surface area (USAC, TCK-PBM, 2560.4 m2/g) was used for the preparation of our composite with potassium permanganate (KMnO4). The physical characteristics of this As-treated USAC sample were analysed through XRD, SEM and EDX analysis. The XRD analysis was used to examine structural properties; surface analysis undertaken by SEM; EDX analysis was used to measure the metal content of the sample as well as the content after treatment with KMnO4. It was shown USAC treated with KMnO4 had more than a 10.5 μg acidic group by the Boehm titration method. The electrochemical properties of KMnO4-USAC were investigated for varying electrolyte concentration (0.1, 0.5, 1.2 and 6 M) at ambient temperature (25 °C) and the electrode showed great electrochemical performance after ten cycles.

The effect of impurities in coal gangue on the sintering and properties (porosity and compressive strength) of porous cordierite ceramics has been investigated by adjusting the amount of impurities by controlling the acid–gangue ratio during acid leaching. The sintering behavior and microstructure of the porous ceramics have been characterized via X-ray diffractometry and scanning electron microscopy. The effects of both the acid–gangue ratio and sintering temperature on the porosity and compressive strength have been also investigated. The results indicated that both porosity and compressive strength of the porous cordierite ceramics prepared using acid-leached coal gangue were evidently improved. The content of the impurities in coal gangue was adjusted via acid leaching by controlling the acid–gangue ratio. The appropriate content of impurities in coal gangue facilitated the sintering process and improved the porosity and compressive strength of the obtained porous cordierite ceramics.

Novel BiOCl/g-C3N4 thin film photocatalysts were synthesized via a simple two-step spin coating method. The prepared photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy. The photocatalytic activity of the thin films for the degradation of rhodamine B under visible light (λ ≥ 400 nm) was investigated. The results showed that the BiOCl/g-C3N4 thin film photocatalysts exhibited significantly improved visible light absorption compared to the pure BiOCl thin film. The BiOCl/g-C3N4 film showed a rhodamine B degradation efficiency of 81.0% under visible light, which is 23.8 times higher than that of the pure BiOCl thin film. This excellent photocatalytic activity of the BiOCl/g-C3N4 film can be attributed to its efficient electron–hole separation due to the presence of g-C3N4.

A novel nanohybrid of graphene-based Cu2ZnNiSe4 with WO3 nanorods (G-CZNS@W) was successfully synthesized via a simple hydrothermal method to use as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). The characterization technique confirmed the structural and morphologies of the G-CZNS@W nanohybrid, which could show rapid electrons transfer pathway through the WO3 nanorods. Moreover, the as-fabricated G-CZNS@W nanohybrid exhibited synergetic effect between G-CZNS and a WO3 nanorod, which could affect the electrocatalytic activity towards triiodide reaction. The nanohybrid exhibits an excellent photovoltaic performance of 12.16%, which is higher than that of the standard Pt electrode under the same conditions. The G-CZNS@W nanohybrid material as CE thus offers a promising low-cost Pt-free counter electrode for DSSC.

TiO2 thin films with controllable morphology and grain size were prepared via a liquid phase deposition (LPD) technique. The effects of the processing parameters including the (NH4)2TiF6 concentration, solution pH, and (NH4)2TiF6:H3BO3 molar ratio on the grain size and morphology of the films were investigated. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy. The results showed that the deposition parameters significantly affected the growth and nucleation velocities of the crystalline grains, which resulted in the formation of TiO2 films with different morphologies and grain sizes. The capillary stress among the grains of the film, which resulted in the cracking of the film, depended on the size of the grains. Thus, the cracking of the LPD-derived TiO2 films could be mitigated by adjusting the deposition parameters.

The present study was aimed to use of N doped graphene quantum dots (N-GQDs) and N,K co-doped graphene quantum dots (N,K-GQDs) as a fluorescence quenching sensor to determine both mercury and copper in water sample, simultaneously using simple fluorescence protocol. Each of N-GQDs or N,K-GQDs was optimized separately with 1–5% (w/v) HNO3 or KNO3, respectively, and their quantum yields were determined and compared. It was found that N-GQDs, obtained from 3% (w/v) HNO3 doped resulted higher fluorescence intensity at the maximum excitation and emission wavelengths of 370 and 460 nm, respectively, with higher quantum yield (QY = 83.42%) compared with that of undoped GQDs (QY = 16.35%). While N,K-GQDs obtained from 5%(w/v) KNO3 gave somewhat different fluorescence spectrum, but still had the same maximum excitation and emission wavelengths with rather highest QY (94.07%). However, it is interesting that detection sensitivity expressed as slope of their calibration curve (y = 5.43x − 19.48; r2 = 0.9971) of the N-GQDs is rather higher than that (y = 1.29x + 17.66; r2 = 0.9977) of the N,K-GQDs for Hg2+ fluorescence quenching sensor, and the fluorescence intensity of N-GQDs had better selectively quenching effect only by both Hg2+ and Cu2+. Thus, their quenching effects were selected to develop the fluorescence turn-off sensor for trace level of both metal ions in real water samples. For method validation, the N-GQDs exhibited high sensitivity to detect both Hg2+ and Cu2+ with wide linear ranges of 20–100 μM and 100–500 μM, respectively. Limit of detection (LOD) and limit of quantitation (LOQ) were 0.42 μM & 1.41 μM for Hg2+ and 13.19 μM & 43.97 μM for Cu2+, respectively, with their precision expressed as an intra-day and an inter-day analysis of 6.98% & 11.35% for Hg2+ and 11.78% & 9.43% for Cu2+, respectively. Also the study of matrix analysis of the water samples (drinking water and tap water), was carried out using N-GQDs and N,K-GQDs resulted good percentage recoveries in comparison with those using undoped GQDs under the same optimum conditions. Keywords: Graphene quantum dots, N doped GQDs, N,K co-doped GQDs, Fluorescence quenching sensor, Copper (II), Mercury (II)