- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Effects of interface adsorption configurations on dye-sensitized solar cell performance at the stoichiometric and defected TiO2 anatase (101): a theoretical investigation
摘要： Interfacial adsorption configuration plays a crucial role in influencing on the photovoltaic performance of dye-sensitized solar cells (DSSCs), and thus, theoretical investigations are needed to further understand the impacts of different absorption configurations on stoichiometric and defected TiO2 (101) surface on the short-circuit photocurrent density (JSC) and open-circuit voltage (VOC) of DSSCs. Herein, calculations of isolated dyes and dye/TiO2 systems were performed on the donor-π bridge-acceptor (D-π-A) type porphyrin sensitizers bearing different donor moieties and a α-cyanoacrylic acid anchoring group (T1-3), using DFT and TD-DFT methods. And, for the first time, comparative analysis on interfacial electron injection (IET) and density of states (DOS) were carried out on dye/TiO2 system with stoichiometric and defected surface to provide a further insight into the electronic factors in influencing the efficiency of DSSC, which can well explain the experimental variation trends of JSC and VOC. It turned out that attachment via the carboxyl and cynao groups in a tridentate binding mode can result in more efficient IET rates and an upshifted conduction band in comparison with the bidentate attachment. More interestingly, we found that the adsorption configuration on defected surface containing O2c vacancy induced more upshifted CBM and relative fast IET, especially for the bonding mode through two O atoms of carboxyl group.
关键词： interfacial electron transfer,density of states,dye-sensitized solar cells,adsorption configuration,TiO2
更新于2025-09-16 10:30:52
-
Laser synthesis of magnetite-partially reduced graphene oxide nanocomposites for arsenate removal from water
摘要： Herein, we report the development of a facile process for the synthesis of magnetite-partially reduced graphene oxide (Mag-PRGO) without the use of chemical reducing agents or solvents for the efficient removal of arsenate As(V) ions from contaminated water. The Mag-PRGO is synthesized using the laser vaporization-controlled condensation method where a compressed target consisting of metallic iron (Fe) powder and solid graphene oxide (GO) is laser vaporized in an O2–He atmosphere resulting in the simultaneous oxidation of the Fe nanoparticles and the partial reduction of the GO to form the Mag-PRGO nanocomposite where the magnetic Fe3O4 nanoparticles are anchored to the surface of the PRGO nanosheets. FTIR, Raman, XPS, XRD, TEM, and SEM confirm the successful attachment of the magnetic Fe3O4 nanoparticles to the PRGO nanosheets. The Mag-PRGO (50 wt% Fe) adsorbent shows exceptional selectivity for the extraction of As(V) ions with a capacity of 132 mg/g with no leaching of Fe ions into the solution, placing it among the best carbon-based materials for the efficient removal of As(V) from aqueous solutions. The Mag-PRGO displays a 100% removal of As(V) at concentrations up to 100 ppm with 98% and 100% removal within 15 min and 30 min, respectively, at 50 ppm concentration. The excellent agreement of the experimental sorption isotherms with the Langmuir model suggests a monolayer adsorption behavior. The mechanism of As(V) removal is based on surface complexation between the protonated hydroxyl groups on the surface of Mag-PRGO and the monobasic and dibasic arsenate anions forming (Fe–O–As) bonds as confirmed by FTIR and XPS. The Mag-PRGO is easily regenerated with the desorption of the As(V) ions reaching 99% from their maximum sorption capacities using NaOH. The efficient magnetic separation and high chemical stability of Mag-PRGO are demonstrated over six adsorption–desorption cycles of As(V). The Mag-PRGO is proposed as an excellent remediation adsorbent for the extraction of As(V) from contaminated water.
关键词： Magnetite-partially reduced graphene oxide,Arsenate removal,Water remediation,Adsorption,Laser vaporization-controlled condensation
更新于2025-09-16 10:30:52
-
Tailoring of graphene quantum dots for toxic heavy metals detection
摘要： The sensitivity of graphene quantum dots towards toxic heavy metals (THMs; Cd, Hg, Pb) can be improved through doping with nitrogen at the vacant site defects. Using density functional theory, we investigate the adsorption of THMs on the graphene quantum dots (GQDs) and nitrogen-coordinated defective GQDs (GQD@1N, GQD@2N, GQD@3N and GQD@4N) surfaces. Thermochemistry calculations reveal that the adsorption of Pb atom on the surfaces is more favorable than Cd and Hg adsorption. The decoration of the vacant defects with nitrogen on the GQD surface substantially increases the charge transfer and adsorption energy values of THMs on the GQD surface (GQD@4N > GQD@3N > GQD@1N > GQD@2N > GQD). The charge transfer and adsorption energy of lead on each of these surfaces are greater than those of cadmium and mercury (Pb > Cd > Hg). Quantum theory of atoms in molecules analysis and non-covalent interaction plots further validate this result while also confirming that Pb atom has a partially covalent and electrostatic nature of interaction at the nitrogen-coordinated vacant site defects. The electron density values—a criterion of bond strength—for the THM...N interactions are greater than for the THM…C interactions, confirming the observed adsorption energy trends of the THMs on the surfaces. The lowering of the HOMO–LUMO energy gap of the surfaces follows the order Pb > Cd > Hg and also results in increased electrical conductivity, which are consistent with the calculated adsorption energy trends. Significant changes in the energy gap and electric conductivity of the surfaces upon THMs adsorption make them promising sensors for metal detection. Finally, time-dependent density functional theory calculations showed that changes such as peak shifts, peak quenching and appearance of new peaks are seen in the UV–visible absorption spectra of the surfaces upon adsorption of THMs, wherein the shifts in peaks correspond to the magnitude of adsorption energy of THMs on the surfaces. These results should motivate the experimentalists towards using rational and systematic modulation of surfaces as sensors for heavy metal detection.
关键词： Adsorption energy,Toxic heavy metals,Charge transfer,UV–visible absorption spectra,Nitrogen doping,Density functional theory,HOMO–LUMO energy gap,Graphene quantum dots
更新于2025-09-16 10:30:52
-
Simulated revelation of the adsorption behaviours of acetylcholinesterase on charged self-assembled monolayers
摘要： An acetylcholinesterase (AChE)-based electrochemical biosensor, as a promising alternative to detect organophosphates (OPs) and carbamate pesticides, has gained considerable attention in recent years, due to the advantages of simplicity, rapidity, reliability and low cost. The bio-activity of AChE immobilized on the surface and the direct electron transfer (DET) rate between an enzyme and an electrode directly determined the analytical performances of the AChE-based biosensor, and experimental studies have shown that the charged surfaces have a strong impact on the detectability of the AChE-based biosensor. Therefore, it is very important to reveal the behaviour of AChE in bulk solution and on charged surfaces at the molecular level. In this work, the adsorption orientation and conformation of AChE from Torpedo californica (TcAChE) on oppositely charged self-assembled monolayers (SAMs), COOH-SAM and NH2-SAM with different surface charge densities, were investigated by parallel tempering Monte Carlo (PTMC) and all-atom molecular dynamics simulations (AAMD). Simulation results show that TcAChE could spontaneously and stably adsorb on two oppositely charged surfaces by the synergy of an electric dipole and charged residue patch, and opposite orientations were observed. The active-site gorge of TcAChE is oriented toward the surface with the “end-on” orientation and the active sites are close to the surface when it is adsorbed on the positively charged surface and the tunnel cost for the substrate is lower than that on the negatively charged surface and in bulk solution, while for TcAChE adsorbed on the negatively charged surface, the active site of TcAChE is far away from the surface and the active-site gorge is oriented toward the solution with a “back-on” orientation. It suggests that the positively charged surface could provide a better microenvironment for the efficient bio-catalytic reaction and quick DET between TcAChE and the electrode surface. Moreover, the RMSD, RMSF, dipole moment, gyration radius, eccentricity and superimposed structures show that only a slight conformational change occurred on the relatively flexible structure of TcAChE during simulations, and the native conformation is well preserved after adsorption. This work helps us better comprehend the adsorption mechanism of TcAChE on charged surfaces and might provide some guidelines for the development of new TcAChE-based amperometric biosensors for the detection of organophosphorus pesticides.
关键词： electrochemical biosensor,carbamate pesticides,molecular dynamics simulations,conformation,organophosphates,acetylcholinesterase,self-assembled monolayers,adsorption orientation
更新于2025-09-16 10:30:52
-
A DFT study on functionalization of acrolein on Ni-doped (ZnO)6 nanocluster in dye-sensitized solar cells
摘要： In this work, the functionalization of Acrolein on the Nickel-doped Zn6O6 (A-NiZn5O6) nanocluster with different adsorption configurations (C, M1 & M2) as the π conjugated bridging in dye-sensitized solar cells (DSSC) compared with the anchoring group [6,6] - phenyl-C61-butyric acid methyl ester (PCBM) have been investigated through (DFT/TD-DFT)) calculations by Gaussian 09 program. The interaction between the NiZn5O6 and the Acrolein has been explored through three functional groups are ? O Carbonyl group (C), –CH Methyl group (M1), and –CH2 Methylene group (M2) of the Acrolein. The nature of the interaction between the Acrolein and NiZn5O6 has been exhaustively studied in terms of energy gap (Eg), global reactivity descriptors, molecular geometries, adsorption energy, the density of states, Mulliken atomic charges, molecular electrostatic potential, and the UV-Vis spectra for each adsorption site. The frontier molecular orbital analysis study indicated that all dyes could give a suitable electron vaccination from the LUMO orbital of A-NiZn5O6 to the HOMO orbital of PCBM. The adsorption process significantly improved the incident photon to the current conversion potency of the A-NiZn5O6. The determination of density functional theory calculations revealed that the C site of A-NiZn5O6 material was faced with a lower chemical hardness and energy gap (Eg) as well as a higher electron accepting power and light harvesting efficiency compared to other sites.
关键词： Optics,Theoretical chemistry,Adsorption,DFT,Density of states,Nanotechnology,NiZn5O6,DSSC,Materials chemistry
更新于2025-09-12 10:27:22
-
Impurities in large scale produced Nd-doped phosphate laser glasses. II. Pt ion and Pt inclusion
摘要： Platinum is a special kind of impurity in Nd-doped phosphate laser glasses. Firstly, its presence in the glass depends on the production processes, rather than the purity of the raw materials used. Secondly, there coexist Pt ion and Pt inclusion in the glass, which one is the oxidized and the other is the reduced. The detection for these two kinds of Pt impurities in the large-scale produced Nd-doped phosphate laser glasses can re?ect the control level and stability of the processes. To determine more accurately the content of Pt ion in the glass, a hemi-cyanine dye, instead of SnCl2 previously used, is utilized to color Pt ion solution by dissolving the glass. On the basis of such a new hemi-cyanine spectrophotometric analysis, the factor of proportionality between Pt ion content and its absorption coe?cient at 400 nm is determined and discussed. To avoid the interference from other cations in the multi-cation solution by dissolving the glass, when doing ICP-MS analysis for Pt, a magnetic poly-ionic liquid is synthesized successfully by bonding an ionic liquid to nano-Fe3O4 particles covered by C. Such a new magnetic poly-ionic liquid can adsorb Pt ions with a better selection. The element distribution of Pt, O and P for di?erently sized Pt inclusions in the glass is analyzed by EPMA.
关键词： Pt ion,Pt inclusion,Selective adsorption for Pt ion,EPMA,Spectrophotometry,Nd-Doped phosphate laser glass
更新于2025-09-12 10:27:22
-
Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Function of <scp>TiCl</scp><sub/>4</sub> Posttreatment in Photoanode
摘要： Energy is the key factor for any living creature to exist in this universe. The advent of industrialization and increase in population have led to a surge in the crisis for energy. The reduction of our dependence on fossil fuels (oil, coal, and natural gas), as well as the evolution towards a cleaner future, requires the large deployment of sustainable renewable energy sources. Among them solar energy is the most abundant and also available throughout the year. Moreover, the solar energy has the greatest potential to fulfill the thirst for energy and the need for innovation of clean and eco-friendly technologies. In this perspective, developing solar cells is one of the best approaches to convert solar energy into electrical energy based on photovoltaic effect. Solar cells based on crystalline silicon and thin film technologies are often referred to as first- and second-generation solar cells. The demerits in that are the limited availability and the cost of silicon. An emerging third-generation photovoltaics have been developed as an alternate to it. These include Dye-sensitized solar cells (DSSCs), organic photovoltaic, quantum dots and recently perovskite solar cells. DSSCs based on nanocrystalline TiO2 as a photo-anode have attracted a lot of scientific and technological interest since their breakthrough in 1991 [1]. The two main functional aspects of charge generation and transport are no longer combined in one material but separated in different materials, i.e. a sensitizing dye, a wide-band-gap semiconductor (TiO2), and a liquid redox electrolyte [2].
关键词： photoanode,TiO2,dye-sensitized solar cells,electron transport,TiCl4 posttreatment,dye adsorption,photocurrent generation
更新于2025-09-12 10:27:22
-
First-principle study of SO2 adsorption on Fe/Co-doped vacancy defected single-walled (8, 0) carbon nanotubes in sensor applications
摘要： To explore the excellent sensor for detecting the pollution gas SO2, the adsorptions of SO2 molecule on the surfaces of Fe/Co-doped carbon nanotubes (CNTs) and single vacancy defected (8, 0) CNTs were investigated by using density functional theory (DFT). In addition, the adsorption energies, geometries, energy gaps and electronic structures were analyzed. The results showed that Fe/Co-doping and single-vacancy-defected can improve the adsorption and sensitiveness of CNTs toward SO2. Considering the changes of energy gap before and after the SO2 molecule adsorbed on each modiˉed CNTs and its adsorption strength, Fe-doped CNTs (Fe-CNTs) and Co-doped site-2 single-vacancy-defected CNTs performed better for detecting SO2 molecule. With the decreasing number of electrons of the doped atom (Fe, Co, Ni), the adsorption became more stable. The results of this paper are profound and meaningful for designing SO2 sensing devices.
关键词： SO2,adsorption,carbon nanotubes,co-doping,vacancy,Fe-doping
更新于2025-09-12 10:27:22
-
A model for real time, <i>in situ</i> estimation of cesium coverage on metal substrate using infrared imaging under vacuum
摘要： The present work is to develop an infra-red (IR) camera based in situ diagnostic tool for the determination of cesium (Cs) coverage suitable for ion source applications. Cs seeding is done to reduce the surface work function that enhances the surface assisted negative hydrogen ion production. The temporal Cs deposition on a metal surface (for, e.g., tungsten or molybdenum) follows Langmuir adsorption isotherm (LAI) kind of behavior. The surface temperature varies while the Cs deposition is reflected in the IR camera temperature measurements for a constant surface emissivity value. In this paper, a model on the relationship between Cs coverage in correlation with surface emissivity and temperature variation based on the theory of LAI is presented. A surface ionization probe (SIP) in the form of a cathode-anode assembly together with an IR camera viewing arrangement is designed to measure the Cs flux and the surface temperature simultaneously to test our model. In the present experiment, the Cs flux measurement using SIP is validated with a standard quartz crystal microbalance (QCM). The proposed model would be useful to correlate Cs coverage on plasma grid-like surface conditions under negative ion source relevant vacuum conditions.
关键词： surface ionization probe,infra-red camera,cesium coverage,quartz crystal microbalance,Langmuir adsorption isotherm
更新于2025-09-12 10:27:22
-
Additive‐Free Non‐Fullerene Organic Solar Cells
摘要： CeMnOx catalyst was synthesized by the combustion method, and the supported Ti/CeMnOx catalyst was subsequently prepared by wetness impregnation. Ti/CeMnOx catalyst exhibited higher N2 selectivity than CeMnOx catalyst in the selective catalytic reduction of NO by NH3 (NH3-SCR), and the generation of side products including in N2O and NO2 were discussed. N2 adsorption/desorption, X-ray di?raction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (TPR), NH3 temperature-programmed desorption (TPD), and in situ di?use re?ectance infrared Fourier transform spectroscopy (DRIFTS) were carried out to reveal the promotion e?ect of TiO2 on the N2 selectivity of CeMnOx catalyst. Results indicated that loading TiO2 weakened the redox ability and enhanced the NH3 adsorption ability of CeMnOx catalyst, and thus inhibited NO/NH3 oxidation and facilitated the Eley?Rideal reaction pathways even at higher temperature.
关键词： TiO2,NH3 adsorption,redox ability,CeMnOx catalyst,N2 selectivity,NH3-SCR
更新于2025-09-11 14:15:04