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Enhanced Photoelectrocatalytic H <sub/>2</sub> Evolution over Two-Dimensional MoS <sub/>2</sub> Nanosheets Loaded on Cu-Doped CdS Nanorods
摘要： Transition-metal ion doping and efficient decoration by using a co-catalyst have been proven to effectively inhibit the recombination of photogenerated electron-hole pairs and broaden the visible-light response region. Here, we have constructed MoS2 nanosheets decorated on a copper-doped CdS nanorod composite as a noble-metal-free photoelectrocatalyst. This kind of composite material was constructed through a simple solvothermal method. The morphology, structure, chemical states, photoelectrochemical properties, and other properties were tested by using a diverse range of analytical techniques. Owing to the Cu2 + doping and the excellent electron-capturing ability of MoS2, 5 % MoS2/Cu(cid:0) CdS (with 7 % Cu2 + doping in CdS) exhibits excellent hydrogen evolution reaction with a rate of 10.18 mmol h(cid:0) 1 g(cid:0) 1, which is about 48 times higher than that of pure CdS. A significant increase in the photoelectrochemical performance of the composite catalytic material benefits from the synergistic effect between CdS and MoS2 and fast interfacial charge transfer, owing to the Cu2 + doping. These findings provide a new thought for further research of the ion doping in photoelectrocatalytic field.
关键词： CdS,hydrogen evolution reaction,photoelectrochemical performance,MoS2,Cu2 + doping
更新于2025-09-04 15:30:14
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Effect of doping Gd2O3 on dielectric and piezoelectric properties of BaZr0.1Ti0.9O3 ceramics by sol–gel method
摘要： The effects of sintering temperature and doping amount of gadolinium ions on the microstructures and electrical properties of sol gel derived Ba (Zr0.1Ti0.9) O3 + xGd ceramics were investigated in this manuscript. XRD analysis showed that the main crystalline phase of BZT-xGd ceramic samples exhibit a perovskite structure without significantly change. The sample sintered at 1350 °C and doped with gadolinium ions of 0.5 mol% has uniform grain size and compact morphology. And the sample(1350 °C—0.5 mol%) also has a high piezoelectric charge coefficient of 131.33 pC/N, large plane electromechanical coupling coefficient of 0.22, high dielectric constant of 10504, and small dielectric loss of 0.01. The correlation of dielectric and piezoelectric properties of BZT-xGd ceramics with doping amount of Gd3+ ion has been explained by the lattice theory.
关键词： BZT-xGd ceramics,dielectric properties,sol–gel method,gadolinium doping,piezoelectric properties
更新于2025-09-04 15:30:14
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Nitrogen-Doped Durian Shell Derived Carbon Dots for Inner Filter Effect Mediated Sensing of Tetracycline and Fluorescent Ink
摘要： Photoluminescent carbon dots have gained increasing attention in recent years due to their unique optical properties. Herein, a facile one-pot hydrothermal process is used to develop nitrogen-doped carbon dots (NCDs) with durian shell waste as the precursor and Tris base as the doping agent. The synthesized NCDs showed a quantum yield of 12.93% with a blue fluorescence under UV-light irradiation and maximum emission at 414 nm at an excitation wavelength of 340 nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy showed the presence of nitrogen and oxygen functional groups on the NCD surface. The particles were quasi-spherical with an average particle diameter of 6.5 nm. The synthesized NCDs were resistant to photobleaching and stable under a wide range of pH but were negatively affected by increasing temperature. NCDs showed high selectivity to Tetracycline as the fluorescence of NCDs was quenched significantly by Tetracycline as a result of the inner filter effect. Based on sensitivity experiments, a linear relationship (R2 = 0.989) was developed over a concentration range of 0–30 μM with a detection limit of 75 nM (S/N = 3). The linear model was validated with two water samples (lake water and tap water) with relative recoveries of 98.6–108.5% and an RSD of <3.5%.
关键词： Fluorescent ink,Tetracycline detection,Durian shell waste,Nitrogen doping,Carbon dots
更新于2025-09-04 15:30:14
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Influence of Boron Antisite Defects on the Electrical Properties of MBE‐Grown GaAs Nanowires
摘要： Nanowires provide a platform for the integration of heterogeneous materials in III–V systems grown on Si. BxGa1(cid:1)xAs is an interesting material for strain applications, which has not yet been studied in nanowire form. The incorporation of boron in GaAs nanowires is investigated via DC-IV measurements. In transmission electron microscopy analysis a high concentration of boron is found at the nanowire edges, indicating surface segregation during growth. Nanowires grown under boron flux are found to exhibit Ohmic contacts and low contact resistances with p-type metallizations such as Au/Zn/Au or Cr/Au. Back-gated measurements confirmed the p-type behavior of such nanowires, indicating that boron is incorporated on antisite defects where it acts as a doubly-charged acceptor. This offers a new route for the inclusion of p-doped layers in GaAs-based nanowire heterostructures and the subsequent formation of Ohmic contacts.
关键词： boron doping,B:GaAs,nanowires,molecular beam epitaxy
更新于2025-09-04 15:30:14
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Influence of rare earth material (Sm3+) doping on the properties of electrodeposited Cu2O films for optoelectronics
摘要： Herein, we report samarium (Sm) dopant concentration effect on Cu2O films characteristics prepared by electrodeposition method. XRD patterns of the films indicated that pristine and Sm:Cu2O films have polycrystalline cubic structure with (111) preferred orientation. It was seen from the SEM photographs pinhole free dense triangle shaped grains for undoped Cu2O thin films and the grain size was decreased as concentration of samarium was increased. Raman spectroscopy showed peaks at 108, 146, 217, 413 and 637 cm?1 which conformed the Cu2O phase formation and intensity of the peaks was decreased with a increase in dopant concentration. UV–Vis spectra exhibited that the absorption value of Cu2O films is increased gradually with reduction in band gap value for the increase of samarium content. Photoluminescence (PL) spectra revealed that all films display a visible light emissions and its intensity was reduced due to increase in doping concentration. Photosensitivity observation study indicated that the photocurrent of deposited Cu2O films was increased along with the increase in dopant material concentration.
关键词： Electrodeposition,Cu2O films,Optoelectronics,Structural properties,Samarium doping,Optical properties,Photosensitivity
更新于2025-09-04 15:30:14
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Effect of Ce and Mn co-doping on photocatalytic performance of sol-gel TiO2
摘要： Co-doped titanium dioxide was synthesized by doping with manganese (Mn) and cerium (Ce) through a sol-gel method for the degradation of diclofenac (DCF). The synthesized products were successfully characterized by X-ray diffraction (XRD), Raman spectroscopy, Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Nitrogen physisorption at 77 K, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance (UV-DRS), photoluminescence spectroscopy (PL) and total organic carbon (TOC). It was shown that co-doping increased the specific surface area, improved the visible light absorption and extended the lifetime of photogenerated charge carriers. Furthermore, the results of the photocatalytic experiments show that the photodegradation rate of diclofenac can be approached by pseudo first-order kinetics and it followed the Langmuir-Hinshelwood model very well. The co-doped catalyst with 0.6 % Mn and 1 % Ce molar ratios appeared to be the most photoactive catalyst with 94 % of DCF removal and an apparent rate constant of 0.012 min-1.
关键词： Photocatalysis,co-doping,manganese and cerium,titanium dioxide,diclofenac
更新于2025-09-04 15:30:14
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The effect of titanium excess and deficiency on the microstructure and dielectric properties of lanthanum doped Ba0.55Sr0.45TiO3 with colossal permittivity
摘要： The temperature dependent dielectric properties of (Ba0.54875Sr0.44875La0.0025)Ti(1+x)O3 with both an excess and a deficiency of 0.25 mol.% TiO2 were investigated. The samples were prepared by the mixed oxide method and sintered in a conventional oven at temperatures ranging from 1400 °C to 1475 °C. The cubic perovskite structure was confirmed with XRD at room temperature. The sample with an excess of 0.25 mol.% Ti exhibited reduced grain growth while abnormal grain growth was observed for samples without Ti modification. Samples exhibited colossal permittivity for all modified compositions. With a 0.25 mol.% deficiency of Ti a permittivity over 65,000 and a tan δ under 0.05 were measured over a temperature range of -68 °C to 150 °C and a frequency range between 50 kHz and 1 MHz. This paper shows that by fine tuning the composition, materials with new, exciting and widely adjustable dielectric properties can be achieved.
关键词： Doping,Colossal permittivity,Lanthanum,BST
更新于2025-09-04 15:30:14
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Designing Conjugated Polymers for Molecular Doping: The Roles of Crystallinity, Swelling, and Conductivity in Sequentially-Doped Selenophene-Based Copolymers
摘要： Although chemical doping is widely used to tune the optical and electrical properties of semiconducting polymers, it is not clear how the degree of doping and the electrical properties of the doped materials vary with the bandgap, valence band level, and crystallinity of the polymer. We address this question utilizing a series of statistical copolymers of poly(3-hexylthiophene) (P3HT) and poly(3-heptylselenophene) (P37S) with controlled gradients in bandgap, valence band position and variable crystallinity. We dope the copolymers in our series with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) using solution sequential processing (SqP). We then examine the structures of the films using grazing incidence wide-angle x-ray scattering (GIWAXS), differential scanning calorimetry (DSC) and ellipsometric porosimetry, and the electrical properties of the films via the AC Hall effect. We find that the ability of a particular copolymer to be doped is largely determined by the offset of the polymer’s valence band energy level relative to the LUMO of F4TCNQ. The ability of the carriers created by doping to be highly mobile and thus contribute to the electrical conductivity, however, is controlled by how well the polymer can incorporate the dopant into its crystalline structure, which is in turn influenced by how well it can be swelled by the solvent used for dopant incorporation. The interplay of these effects varies in a non-monotonic way across our thiophene:selenophene copolymer series. The position and shape of the polaron absorption spectrum correlate well with the polymer crystallinity and carrier mobility, but the polaron absorption amplitude does not reflect the number of mobile carriers, precluding the use of optical spectroscopy to accurately estimate the mobile carrier concentration. Overall, we find that the degree of crystallinity of the doped films is what best correlates with conductivity, suggesting that only carriers in crystalline regions of the film, where the dopant counterions and polarons are forced apart by molecular packing constraints, produce highly mobile carriers. With this understanding, we are able to achieve conductivities in this class of materials exceeding 20 S/cm.
关键词： semiconducting polymers,conductivity,ellipsometric porosimetry,GIWAXS,solution sequential processing,valence band level,F4TCNQ,poly(3-heptylselenophene),AC Hall effect,poly(3-hexylthiophene),DSC,bandgap,chemical doping,crystallinity
更新于2025-09-04 15:30:14
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Photoelectron Spectroscopy and Theoretical Study of Cr <sub/><i>n</i> </sub> Si <sub/> 15– <i>n</i> </sub><sup>–</sup> ( <i>n</i> = 1–3): Effects of Doping Cr Atoms on the Structural and Magnetic Properties
摘要： CrnSi15?n? (n = 1?3) clusters were investigated by using size-selected anion photoelectron spectroscopy combined with density functional theory calculations. The results show that the most stable structure of CrSi14? is of C2v symmetry with the Cr atom encapsulated in a Si14 cage which can be viewed as a boat-shaped Si10 unit capped by four additional silicon atoms. A large HOMO?LUMO gap of neutral CrSi14 is confirmed based on the photoelectron spectrum of CrSi14?. Cr2Si13? has two isomers nearly degenerate in energy: one can be characterized as one Si atom interacting with a Cr2Si12 hexagonal prism while the other can be viewed as one Si atom capping a distorted Cr2Si12 hexagonal antiprism. Cr3Si12? has a D6d symmetric wheel structure in which three Cr atoms form an axle surrounded by 12 Si atoms. The magnetic moments of CrSi14?, Cr2Si13?, and Cr3Si12? increase from 1 to 3 μB and then to 7 μB with the increasing number of Cr atoms in the clusters. The magnetic moments of Cr2Si13? and Cr3Si12? are mainly contributed by the surface Cr atoms.
关键词： Photoelectron spectroscopy,Silicon clusters,Chromium doping,Density functional theory,Magnetic properties
更新于2025-09-04 15:30:14
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Band Gap Control in Bilayer Graphene by Co-Doping with B-N Pairs
摘要： The electronic band structure of bilayer graphene is studied systematically in the presence of substitutional B and/or N doping, using density functional theory with van der Waals correction. We show that introduction of B-N pairs into bilayer graphene can be used to create a substantial band gap, stable against thermal fluctuations at room temperature, but otherwise leaves the electronic band structure in the vicinity of the Fermi energy largely unaffected. Introduction of B-N pairs into B and/or N doped bilayer graphene likewise hardly modifies the band dispersions. In semiconducting systems (same amount of B and N dopants), however, the size of the band gap is effectively tuned in the presence of B-N pairs.
关键词： density functional theory,van der Waals correction,band gap,B-N doping,bilayer graphene
更新于2025-09-04 15:30:14