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Graphene Adsorption and Separation Functional Materials
摘要： Graphene and its derivatives have highly been embraced in the development and application of new type of adsorption and separation functional materials, due to its unique structure and superior performance. This paper gives a comprehensive review to the recent studies about the adsorption and separation functional materials, including graphene, graphene oxide, graphene gel, graphene-based sponge, graphene separation membrane as well as graphene continuous oil absorption and separation materials. Moreover, the preparation methods and application prospect were mainly utilized to illustrate the research progress. Especially, we predict that layered graphene membrane and graphene continuous oil absorption and separation materials may be the most research worthy.
关键词： Functional Material,Adsorption,Graphene Oxide,Graphene,Separation
更新于2025-09-23 15:21:21
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Photocatalytic degradation and adsorption of phenol by solvent-controlled TiO2 nanosheets assisted with H2O2 and FeCl3: Kinetic, isotherm and thermodynamic analysis
摘要： Hydrofluoric acid (HF) has been widely employed to regulate the surface characteristics of TiO2 containing sheet-like morphology with (001) facets for various environmental applications. However, carcinogenic effects associated with HF are the main stumbling blocks on its way towards global commercialization. In the same line of action, an eco-friendly approach for the synthesis of anatase TiO2 nanosheets (TNSs) via employing hydrothermal process and N, N dimethylformamide (DMF) as a novel morphology-controlling agent has been reported. The as-produced TNSs were characterized by XRD, HRTEM, Raman, FTIR, XPS and DRS characterizations. The photoactivity of as-produced TNSs was studied for photocatalytic degradation of phenol under visible light irradiation in the presence of green oxidants such as hydrogen peroxide (H2O2) and ferric chloride (FeCl3) to produce free hydroxyl radicals for speedily reduction of recombination of photogenerated electrons hole-pairs. The results revealed that as-produced TNSs could activate by green oxidants with yielding upto 94.19 and 97.12 % phenol degradation in the presence of H2O2 and FeCl3, respectively. Moreover, phenol adsorption data was well explained via pseudo first order and pseudo second order kinetics while Langmuir and Freundlich isotherms were more suitable to explain the adsorption of phenol onto TNSs, providing maximum adsorption capacity up to 23.596 mg/g. Various thermodynamic parameters were evaluated, suggesting the favourable, spontaneous and endothermic adsorption process. The values of activation energy (18.505 kJ/mol) confirmed the physical adsorption of phenol onto TNSs. The excellent aptitude of anatase TNSs to produce hydroxyl radicals and super-oxides radicals with promptly lessening of recombination of photogenerated electron hole-pairs makes them motivated applicant for wastewater treatment.
关键词： N, N dimethylformamide,green oxidants,adsorption mechanism,Hydrothermal process,TiO2 nanosheets,phenol
更新于2025-09-23 15:21:01
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Controlling dye coverage instead of addition of organic acid to reduce dye aggregation in dye-sensitized solar cells
摘要： The photo-generated electron injection yield of dye-sensitized solar cells (DSSCs) based on donor-acceptor conjugated dyes is lowered by the aggregation of surface adsorbed organic dyes that pose a low-photoenergy conversion efficiency. Coadsorbates used to prevent the aggregation cause to decompose or detach the dye molecules anchored on the TiO2 surface. In this study, the effect of coadsorption of organic acid and organic dyes on photovoltaic performances was systematically scrutinized by means of adsorption isotherms and photovoltaic measurements. Our laboratory synthesized {0 1 0}-faceted TiO2 (PA TiO2) and P25 TiO2 were used as meso-porous nanocrystals, D149 organic dye was used as a sensitizer and cheno-deoxycholic acid, CDA, was used as a coadsorbate. The coadsorption of CDA reduces the adsorption parameters, maximum adsorption density (Qm) and adsorption constant (Kad), and the reduction depended on the type of TiO2. The photovoltaic performance indicates that the D149 dye has the best dye coverage at around 70% for the effective photovoltaic energy conversion. The coadsorption of CDA increased the photovoltaic performances of DSSCs based on P25 TiO2 but, CDA decreased the photovoltaic performances of DSSCs based on PA TiO2 due to the reduction of the dye coverage below 70%. The results suggest that the coadsorption of organic acids is not necessary if the particular TiO2 can maintain its coverage at the best coverage. Thus, the requirement of coadsorbates to reduce the dye aggregation depends on the type of TiO2 used in DSSCs.
关键词： Coverage,Adsorption isotherms,Coadsoptions,Aggregations,Photovoltaic performances,Dye-sensitized solar cells
更新于2025-09-23 15:21:01
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Ultrafast Laser Processing of Nanostructured Patterns for the Control of Cell Adhesion and Migration on Titanium Alloy
摘要： Femtosecond laser texturing is a promising surface functionalization technology to improve the integration and durability of dental and orthopedic implants. Four different surface topographies were obtained on titanium-6aluminum-4vanadium plates by varying laser processing parameters and strategies: surfaces presenting nanostructures such as laser-induced periodic surface structures (LIPSS) and ‘spikes’, associated or not with more complex multiscale geometries combining micro-pits, nanostructures and stretches of polished areas. After sterilization by heat treatment, LIPSS and spikes were characterized to be highly hydrophobic, whereas the original polished surfaces remained hydrophilic. Human mesenchymal stem cells (hMSCs) grown on simple nanostructured surfaces were found to spread less with an increased motility (velocity, acceleration, tortuosity), while on the complex surfaces, hMSCs decreased their migration when approaching the micro-pits and preferentially positioned their nucleus inside them. Moreover, focal adhesions of hMSCs were notably located on polished zones rather than on neighboring nanostructured areas where the protein adsorption was lower. All these observations indicated that hMSCs were spatially controlled and mechanically strained by the laser-induced topographies. The nanoscale structures influence surface wettability and protein adsorption and thus influence focal adhesions formation and finally induce shape-based mechanical constraints on cells, known to promote osteogenic differentiation.
关键词： cell adhesion,multiscale-patterning,wettability,human mesenchymal stem cell,femtosecond laser,cell spreading,cell motility,protein adsorption
更新于2025-09-23 15:21:01
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A Wearable UV Sensor Based on Carbon Nanotube Coated Cotton Thread
摘要： A fabric-compatible UV sensor is presented using a cellulose-based thread coated with single wall carbon nanotube ink. Two-terminal resistive responses of the thread were measured upon exposure to UV, and the effects of intensity, wavelength and on/off cycling were studied. The sensor was tested in the field under direct sunlight, demonstrating practical usability for a wearable/flexible UV sensor system. The results here confirm the potential for an inexpensive wearable sensor in contrast to the conventional rigid and bulky solid state detectors.
关键词： cellulose thread,wearable ultraviolet sensor,ultraviolet radiation,oxygen desorption-adsorption,single wall carbon nanotube
更新于2025-09-23 15:21:01
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Bare Silica Opals for Real-Time Humidity Sensing
摘要： The photonic properties of 3D colloidal crystals made of St?ber silica spheres are shown to significantly depend on the relative humidity of the environment. The photonic bandgap of bare artificial opals formed by hydrophilic silica markedly varies in humid air along the entire range of water vapor concentration without the need for infiltration of functionalization. The optical changes are highly sensitive to humidity variation (especially in low-humidity range) and very fast response times of 60 ms, mainly ascribed to the absence of intermediate processes, the favorable bandgap characteristics (high intensity and sharp edges) and the high air accessibility to the open opal voids. Contrary to common approaches for photonic crystal sensors—seeking visual detection via large spectral shifts but having important shortcomings,—it is demonstrated that the well-defined photonic bandgap of bare silica opals allows, even for moderate shifts, outstanding sensing performance by proper monitoring with inexpensive equipment (no spectroscopic detection is needed). As a result, the rapid and reproducible photonic response enables accurate, real-time retrieval of the ambient humidity. The economical, one-step fabrication, and the efficient performance make silica artificial opals suitable for a new type of precise, low-cost, and real-time humidity sensors.
关键词： water vapor adsorption/desorption,real-time sensing,humidity sensors,artificial silica opals,photonic colloidal crystals
更新于2025-09-23 15:21:01
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Graphene Quantum Dot Oxidation Governs Noncovalent Biopolymer Adsorption
摘要： Graphene quantum dots (GQDs) are an allotrope of carbon with a planar surface amenable to functionalization and nanoscale dimensions that confer photoluminescence. Collectively, these properties render GQDs an advantageous platform for nanobiotechnology applications, including optical biosensing and delivery. Towards this end, noncovalent functionalization offers a route to reversibly modify and preserve the pristine GQD substrate, however, a clear paradigm has yet to be realized. Herein, we demonstrate the feasibility of noncovalent polymer adsorption to GQD surfaces, with a specific focus on single-stranded DNA (ssDNA). We study how GQD oxidation level affects the propensity for polymer adsorption by synthesizing and characterizing four types of GQD substrates ranging ~60-fold in oxidation level, then investigating noncovalent polymer association to these substrates. Adsorption of ssDNA quenches intrinsic GQD fluorescence by 31.5% for low-oxidation GQDs and enables aqueous dispersion of otherwise insoluble no-oxidation GQDs. ssDNA-GQD complexation is confirmed by atomic force microscopy, by inducing ssDNA desorption, and with molecular dynamics simulations. ssDNA is determined to adsorb strongly to no-oxidation GQDs, weakly to low-oxidation GQDs, and not at all for heavily oxidized GQDs. Finally, we reveal the generality of the adsorption platform and assess how the GQD system is tunable by modifying polymer sequence and type.
关键词： molecular dynamics simulations,Graphene quantum dots,oxidation level,ssDNA,adsorption,noncovalent functionalization,fluorescence quenching
更新于2025-09-23 15:21:01
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Three-dimensional biogenic C-doped Bi2MoO6/In2O3-ZnO Z-scheme heterojunctions derived from a layered precursor
摘要： Novel 3D biogenic C-doped Bi2MoO6/In2O3-ZnO Z-scheme heterojunctions were synthesized for the first time, using cotton fiber as template. The as-prepared samples showed excellent adsorption and photodegradation performance toward the hazardous antibiotic doxycycline under simulated sunlight irradiation. The morphology, phase composition and in situ carbon doping could be precisely controlled by adjusting processing parameters. The carbon doping in Bi2MoO6/In2O3-ZnO was derived from the cotton template, and the carbon content could be varied in the range 0.9–4.4 wt.% via controlling the heat treatment temperature. The sample with Bi2MoO6/In2O3-ZnO molar ratio of 1:2 and carbon content of 1.1 wt.% exhibited the highest photocatalytic activity toward doxycycline degradation, which was 3.6 and 4.3 times higher than those of pure Bi2MoO6 and ZnInAl-CLDH (calcined layered double hydroxides), respectively. It is believed that the Z-scheme heterojunction with C-doping, the 3D hierarchically micro–meso–macro porous structure, as well as the high adsorption capacity, contributed significantly to the enhanced photocatalytic activity.
关键词： Adsorption,ZnInAl-layered double hydroxides (LDH),Bi2MoO6,Biotemplate,Photocatalysis
更新于2025-09-23 15:21:01
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Numerical model for the chemical adsorption of oxygen and reducing gas molecules in presence of humidity on the surface of semiconductor metal oxide for gas sensors applications
摘要： Charge transfer between the interacting gas molecules and the surface of the sensing layer is the main mechanism for the detection of gases in semiconductor metal oxides. In the presented work, the Wolkenstein's theory of adsorption is used instead of the conventional Langmuir isotherm for the numerical modelling of adsorption of oxygen, reducing gas (CO) molecules and water vapours. A numerical model of chemical adsorption of these gas species at the surface of tin oxide (SnO2) semiconductor gas sensor is presented in this paper. Using this model, quantitative calculation of the combined effect of environmental oxygen, reducing gas (CO) and water vapor adsorption on various electronic properties like electrical conductivity, surface potential and the work function of the metal oxide surface has been carried out. The surface coverage of the chemically adsorbed oxygen gas molecules is simulated as a function of oxygen gas pressure, the temperature of the sensor surface and bulk doping level of the n-type SnO2 semiconductor. Along with oxygen, the adsorption of CO gas is simulated as a function of CO gas pressure at constant atmospheric pressure of Oxygen gas. Furthermore, the sensor response is simulated and compared both in presence of dry Carbon Monoxide (CO) gas as well in the humid environment. It is shown that in the presence of water vapor there is an increase in the conductivity due to the decrease in the surface potential barrier at the semiconductor surface.
关键词： Numerical model,Surface potential,Chemical adsorption,Gas sensor
更新于2025-09-23 15:21:01
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The naked-eye NH3 sensor based on fluorinated graphene
摘要： Graphene has aroused continual and tremendous interest in gas sensing applications because of its unique properties. However, the graphene-based sensors still meet limitations such as inconvenient device fabrication, sustained power supply, specific measuring equipment, etc. Here, we find that fluorinated graphene (FG) shows an obvious color change (from white to dark yellow) in the presence of NH3 which can be observed directly by the naked eye. PL measurement shows that the sensitivity of color change can reach a high value of ca. 4.05 % ppm-1. The density functional theory calculations reveal that the F atoms on FG increase the adsorption ability and charge transfer of NH3 molecules, resulting in the efficient color change. This work develops a naked-eye sensor which needs no device fabrication, power supply or measuring equipment, thus, can be potentially used to manufacture a cheap, sensitive and miniaturized NH3 sensor.
关键词： fluorinated graphene,charge transfer,NH3 sensor,naked-eye color change,adsorption ability
更新于2025-09-23 15:21:01