Developing a novel non-enzyme mimetic in biosensors is of great significance. Here, a synergetic peroxidase-like activity was disclosed for mixed MoS2 quantum dots (MoS2 QDs) and graphene quantum ...dots (GQDs). The high catalytic effect of this mixture was studied on the chemiluminescence system. It was observed that the simultaneous presence of MoS2 QDs and GQDs had a powerful enhancing effect on the chemiluminescence (CL) emission of rhodamine B (RB)-H2O2 reaction. MoS2 QDs and GQDs mixture (prepared with a ratio of 3:2) showed a superior catalytic activity when compared to each of the constituents. A linear relationship was acquired between the CL emission intensity and H2O2 concentration in the range of 1.5–460nmolL−1. On the other hand, since the enzymatic oxidation of cholesterol leads to the production of H2O2; the offered CL system was examined to detect cholesterol after its oxidation by cholesterol oxidase (ChOx) enzyme. Herein, a further improvement was achieved by MoS2 nanosheets. The MoS2 nanosheets increased the performance of ChOx in cholesterol oxidation process. The obtained results confirmed a highly selective and sensitive determination of cholesterol concentration in a linear dynamic range of 0.08–300µmolL−1, with a detection limit (3S) of 35nmolL−1. The developed method was successfully applied for the detection of cholesterol level in human serum samples.
Chemiluminescence sensor for cholesterol using the RB-H2O2 CL reaction catalyzed by GQDs/MoS2 quantum dots. Display omitted
•An enhanced peroxidase-like action was observed for mixed MoS2 and graphene QDs.•The MoS2/graphene QDs sensitized the rhodamine B-H2O2 chemiluminescence system.•A sensitive non-enzyme chemiluminescence probe is developed for serum cholesterol.•The produced H2O2 by cholesterol oxidation was detected by chemiluminescence route.•MoS2 nanosheets improved the performance of cholesterol oxidase.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Heterogeneous photocatalysis using Zn-Co-LDH@BC nanocomposite for degradation of GMF.
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•Hydrothermal preparation of novel and efficient Zn-Co-LDH@BC photocatalyst.•Superior ...photocatalytic activity of Zn-Co-LDH@BC for degradation of gemifloxacin.•High mineralization efficiency of gemifloxacin using Zn-Co-LDH@BC photocatalyst.•A plausible degradation pathway for photocatalytic degradation of gemifloxacin.•Reusability of Zn-Co-LDH@BC catalyst after five photocatalysis run.
The aim of the present study was to investigate the photocatalytic performance of biochar (BC)-incorporated Zn-Co-layered double hydroxide (LDH) nanostructures in gemifloxacin (GMF) degradation as a model pharmaceutical pollutant. The as-prepared Zn-Co-LDH@BC showed high photocatalytic efficiency due to the enhanced separation of photo-generated charge carriers using cobalt hydroxide as well as inhibiting the agglomeration of LDH nanostructures by incorporation of BC. According to the results, 92.7% of GMF was degraded through photocatalysis in the presence of Zn-Co-LDH catalyst. The photocatalytic performance of BC-incorporated Zn-Co-LDH was highly dependent on the solute concentration and photocatalyst dosage. The addition of ethanol caused more inhibiting effect than that of benzoquinone (BQ), indicating the major role of •OH in decomposition of GMF compared to the negligible role of O2•−. A greater enhancement in the photocatalytic degradation of GMF was obtained when the photoreactor containing Zn-Co-LDH@BC nanostructures was oxygenated. Less than 10% drop in the removal efficiency of GMF was observed within five successive operational runs. The results of chemical oxygen demand (COD) analysis indicated the COD removal efficiency of about 80% within 200 min, indicating the acceptable mineralization of GMF. The reaction pathways were also proposed for the photocatalytic conversion of GMF under UV light irradiation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Magnetite was promoted by Ce and CeO2, and anchored onto graphene oxide sheets.•The prepared nanocomposites were evaluated for photocatalytic degradation of OTC.•Fe2.8Ce0.2O4/GO ...nanocomposite displayed great photo-activity in the visible region.•Degradation byproducts of OTC were identified, and a pathway was proposed.•The mechanism of the OTC photodegradation over Fe2.8Ce0.2O4/GO is described.
The main prerequisite of an active visible-light-driven photocatalyst is to effectively utilize the visible light to induce electron-hole (e−/h+) pairs of expanded lifetime. To this end, for the first time, the ternary heterojunctions of CeO2/Fe3O4 /Graphene oxide and Ce3+/ Fe3O4 /Graphene oxide (CeO2/Fe3O4/GO and Fe2.8Ce0.2O4/GO) were prepared via facile ultrasonic-assisted procedures and employed for destruction of oxytetracycline (OTC) under visible light irradiation. The changes in the relative crystal structure, morphology, atomic and surface functional group composition, magnetic, and optic properties of magnetite were uncovered by various techniques. The substantial degradation and mineralization of OTC via visible light/Fe2.8Ce0.2O4/GO system were thoroughly discussed in terms of narrowed band gap energy, the principal function of Ce3+/Ce4+ and Fe2+/Fe3+ redox pairs and GO platelets, enhanced charge separation and transfer, and enlarged active surface area. Furthermore, the performance of visible light/Fe2.8Ce0.2O4/GO system was evaluated for treating real wastewater and its efficiency was investigated using a number of enhancers and scavengers. Finally, the generated byproducts in the course of photodegradation were determined and the oxidation pathway, photocatalytic kinetics, and plausible mechanism were proposed. The results confirmed that the introduced Ce ions and graphene oxide sheets boost the photo-catalytic efficiency of magnetite for photodegradation of OTC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Scheme of dry and steam reforming processes over Ni catalyst supported on MCM-41.
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The catalyst’s performance for hydrogen production is strongly dependent on the proper selection of ...active metals, supports, and promoters. Nickel catalysts can also be a strong and cost-effective succession. Mesoporous supports containing basic sites on the surface are able to suppress carbon deposition and greater stability to the catalyst. Therefore, in this short review, we focus on hydrogen production through reforming processes especially steam and dry reforming and the nickel catalysts’ performance for hydrogen production. Particularly focusing on effective parameters including mesoporous supports (SBA-15, MCM-41, KIT, and SBA-16) and promoters. Since the trapping of active metals into the MCM-41 mesostructure with smaller pores makes them appreciated for catalytic applications, therefore we highlight the recent literature achievements on DRM by promoted/unpromoted Ni catalysts over MCM-41 support for hydrogen production. In this review, attention will be given to different catalyst particles size and the effect of metal dispersion on mesoporous silica supports for enhancing catalytic activities in a comprehensive and comparative manner.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cholesterol oxidase encapsulated in MOF-5 and subsequent H2O2-terephthalic acid reaction in the presence of Ag nanocluster/MoS2 nanosheets catalyst was used for cholesterol determination.
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•Use of porous metal-organic-framework (MOF) as a safe host for cholesterol oxidase.•High stability of enzymes in MOF pores and good efficiency for cholesterol oxidation.•Reaction of created H2O2 and terephthalic acid to form fluorescent hydroxyterephthalate.•Use of Ag nanocluster decorated MoS2 nanosheets hybrid as a new peroxidase catalyst.•High sensitive cholesterol probe based on ChOx/MOF and new peroxidase-like catalyst.
Herein, a nano-porous metal-organic-framework (MOF) was applied as a safe host for cholesterol oxidase (ChOx) enzyme to improve its stability and implement an efficient oxidation process for substrate molecules. Subsequently, a fluorometric method based on the conversion of non-fluorescent terephthalic acid (TA) to 2-Hydroxyterephthalate with a great fluorescence emission was used for fluorescence detection of the generated H2O2. On the other hand, Ag nanocluster (AgNC) decorated MoS2 nanosheets (MoS2-NS) nanocomposite as a new mimetic peroxidase catalyst was exploited in TA-H2O2 reaction. The synthesized enzyme encapsulated MOF and AgNC/MoS2-NS nanocomposites were characterized using scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction and some other analyzing techniques. The results showed a high porous MOF with a high capacity to uptake ChOx enzymes, improving their catalytic activity. The ChOx-MOF hybrid displayed good efficiency for oxidation of cholesterol. Also, an improved peroxidase-like activity was discovered for AgNC/MoS2-NS composite, in comparison with each of the constituents or natural peroxidase enzyme (HRP). As a result, the performance of designed cholesterol probe based on ChOx-MOF and peroxidase-like AgNC/MoS2-NS, was improved significantly, in which it presented a dynamic linear range of 0.06 μM–15 μM with a detection limit (3S) of 0.03 μM. The studied method showed a good selectivity and sensitivity for practical determination of cholesterol and its potential application for cholesterol detection in human blood samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Template-directing strategies for synthesising metal-organic frameworks (MOFs) have brought about new frontiers in materials chemistry due to the possibility of applying control over crystal growth, ...morphology and secondarily generated pores. In particular, hard templates have resulted in performance breakthroughs in catalysis, secondary ion batteries, supercapacitance, drug delivery and molecular sieving by offering facile routes for maximising the surface areas of shape-directed MOFs. In this tutorial review, a variety of hard templates employed to direct MOFs' growth into superior nano-architectures with enhanced functionalities are discussed. Hard templates discussed here include polymers, silica nanostructures, metal oxides, layered metal hydroxides, noble metals, graphene, zeolites and MOFs themselves. These templates can be divided into three broad categories: sacrificial, semi-sacrificial and non-sacrificial templates. We elaborate on the rationale behind the choice of nanomaterials as hard templates, how hard templates direct the synthesis of MOFs, how sacrificial hard templates can be removed from the final product and what the enhanced functionalities of hard-templated MOFs are. In the case of non-sacrificial hard-templates, synergistic effects arising from the coexistence of the MOF and the hard template will also be reviewed.
Template-directing strategies for synthesising metal-organic frameworks (MOFs) have brought about new frontiers in materials chemistry due to the possibility of applying control over crystal growth, morphology and secondarily generated pores.
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•Effect of solvents on membrane performance in presence of ZIF-8.•Preparation of ZIF-8/PVDF UF membranes by DMSO, NMP, DMAc and DMF solvents.•Bigger finger-like for membranes by DMSO ...and DMF compared to DMAc and DMF.•Trend of pure water flux of unmodified membranes was DMSO-0> NMP-0> DMAc-0> DMF-0.
In this research, the PVDF-based nanocomposite membranes modified with ZIF-8 nanocrystals were prepared with various casting solvents containing, DMSO, NMP, DMF and DMAc. The SEM, EDX and AFM analyses were applied to study morphology, distribution of the ZIF-8 in the matrix of the polymer, and surface roughness characteristic of the mixed matrix membranes, respectively. The impact of the solvent type on the structure and filtration efficiency of the resulting membranes was studied by considering the thermodynamic and kinetic factors of the membrane formation. A significant correlation was found between the diffusion rates of the solvent/non-solvent and the sub-layer structure of the membranes. Membranes cast with DMAc and DMF solvents (with relatively high diffusion rates) presented a bigger number of the finger-like cavities with a smaller size compared with membranes prepared by DMSO and NMP with lower diffusion rates. Blending of the ZIF-8 nanoparticles within the membrane matrix with a proper concentration (up to 0.2 wt%) resulted in an increase in the size of the finger-like cavities, lead to increase in the permeability of the resulting membranes. With increasing the ZIF-8 content to 0.5 and 1 wt%, the finger-like pores turned to sponge-like pores. The pure water permeation of the unmodified membranes cast with DMSO, NMP, DMAc and DMF was 258.64, 179.52 156.65 and 10.52 L/m2h, respectively, which was in good agreement with the observed trend for porosity and surface hydrophilicity of the membranes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the present study, heterogeneous electro-Fenton (EF) process was applied to remove the sulfasalazine (SU) pharmaceutical from aqueous solutions. In the first part, 3D graphene loaded with Fe@Fe2O3 ...core-shell nanowires (Fe@Fe2O3/3D-GO) was used as a cathode electrode in the EF process. Graphene oxide (GO) was synthesized for the synthesis of 3D graphene nanocomposites using the improved Hummers’ method and subsequently 3D graphene synthesized by the hydrothermal method using glycine. Finally, Fe@Fe2O3/3D-GO composite was synthesized and its properties were assessed by Scanning electron microscopy, Atomic force microscopy, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy and X-ray diffraction methods. Then, the cathode electrode was prepared using the resulting composite and its performance was evaluated using Cyclic Voltammetry analysis. In the final part of this work, the Fe@Fe2O3/3D-GO electrode was used as the cathode electrode in the heterogeneous EF process to remove SU from aqueous solutions. The effect of operating parameters such as applied current (mA), initial pH of solution, initial pharmaceutical concentration (mg L−1) and process time (min) on pharmaceutical removal efficiency under heterogeneous EF process was investigated by response surface methodology. The results showed that the optimum values for applied current, pH, initial pharmaceutical concentration and electrolysis time were respectively 300 mA, 7, 30 mg L−1 and 100 min, resulting 99.60% of SU removal. Finally, the intermediates of SU degradation were determined by Gas chromatography–mass spectrometry analysis and the amount of mineralization was determined by total organic carbon analysis. About 5.2% drop in the SU removal efficiency was observed within 8 operational runs.
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•3D graphene loaded with Fe@Fe2O3 core-shell nanowires was applied as cathode.•Electro-Fenton method was applied for Sulfasalazine degradation.•Response surface methodology was used to predict the removal efficiency.•Applied cathode demonstrated 99.60% of Sulfasalazine removal efficiency.•Sulfasalazine removal pH was at neutral range.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The release of a large number of antibiotics to the environment has created a shade of sorrow in the scientific community. Herein, two-dimensional (2D)–2D NiO/g-C
3
N
4
photocatalysts were ...synthesized and applied for the photodegradation of tetracycline hydrochloride antibiotic. This 2D–2D heterojunction catalyst showed effective photoactivity due to the large contact area promoting the interfacial charge transfer rate. The improved photoactivities were attributed to the formation of complete face-to-face heterojunctional channels between two nanosheets of NiO and g-C
3
N
4
, which play a major contribution in the transfer of excited charges in the nanocomposite. Besides, the formation of Z-type heterojunction protects the high redox ability of two semiconductors. The photocatalytic activities were high at neutral pH values and decreased when pH values were changed. The photocatalytic activities were also checked in the presence of certain anions such as sulfate, chloride, carbonate), nitrate, and phosphate. Finally, a possible schematic mechanism was planned for charge separation in the nanocomposite.
Graphic abstract
2D-2D NiO/g-C
3
N
4
photocatalysts demonstrate high photocatalytic activity for degradation of tetracycline hydrochloride antibiotic due to the large contact area and Z-scheme heterojunction promoting the interfacial charge transfer rate.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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Recently, ultrathin two-dimensional (2D) materials, known as nanosheets, have attracted great interest owning to their ultimate structural and desirable physical, chemical, thermal, ...electrical, and optical characteristics. Various potential applications of 2D nanomaterials have been reported in electronics/optoelectronics, electrocatalysis, batteries, supercapacitors, solar cells, sensors, photocatalysis, and other environmental processes. Modification of polymeric membranes using nanosheets is increasingly reported in the literature. The incorporation of inorganic nanostructured additives, such as metal oxide and metal hydroxide nanosheets, can impart desired characteristics to the surface and matrix of the membrane and improves its filtration performance. This review summarizes the preparation methods of the metal oxide and metal hydroxide nanosheets, with a special emphasis on the recent advances in this field. The structural and physicochemical properties of the 2D nanosheets have been discussed, and after that, the applications of these nanosheets for modification of polymeric membranes are presented with a focus on the membranes used for environmental applications. Finally, the existing challenges and future perspectives for synthesis and membrane-related applications of 2D metal oxide and metal hydroxide nanosheets are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
