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Photocatalytic oxidative desulfurization and denitrogenation of fuels over sodium doped graphitic carbon nitride nanosheets under visible light irradiation
摘要： A cost-efficient photocatalytic oxidative denitrogenation and desulfurization system for fuels under visible light was developed on the basis of Na doped g-C3N4 nanosheets catalyst. The process adopted molecular O2 as oxidant to substitute for the expensive H2O2, and it adapted to the removal of small molecules of pyridine and thiophene. Na doped g-C3N4 nanosheets were obtained via a simple mixed-calcination pathway using NaCl as Na source. The structural, photophysical and chemical properties of the photocatalysts were characterized and compared to those of the original g-C3N4. It was verified that Na was successfully doped in the g-C3N4 lattice in a uniform chemical state. Moderate amount of Na doped in g-C3N4 generated the highly dispersed and porous nanosheets, which further improved the surface energy and reduce the recombination rate of electron-hole pairs. Na doped g-C3N4 exhibited enhanced performance simultaneously in the photocatalytic oxidative denitrogenation and desulfurization. The optimal catalyst obtained considerable removal efficiency for pyridine and thiophene, depending on its improved structural and photochemical properties by Na doping. A proposed mechanism revealed that the holes acted as the major active species for the denitrogenation and desulfurization, while the superoxide radicals originating from the combination of electron and O2 gave a promotion effect.
关键词： Pyridine,Sodium doping,Graphitic carbon nitride,Thiophene,Photocatalytic oxidation
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - 40Gb/s Carrier Depletion-Based Silicon Micro-Ring Modulators
摘要： A high-speed silicon microring modulator based on a titanium-doped silicon rib waveguide has been demonstrated. Small footprint of 26.5 μm × 26.5 μm with low driving voltage of 1.5 V and 22 dB extinction ratio at 20 Gb/s modulation has been achieved. The high-speed performance is attributed to the low capacitance of the device and the efficient plasma dispersion effect in silicon. Moreover, the modulator exhibits a low propagation loss of 2.5 dB/cm and a high modulation efficiency of 1.5 V·cm. The device is fabricated on a silicon-on-insulator (SOI) wafer with a 220 nm top silicon layer and a 2 μm buried oxide layer. The rib waveguide has a width of 500 nm and a height of 220 nm with a slab height of 150 nm. The titanium doping concentration is 1×10^20 cm^{-3}. The modulator is characterized using a lightwave component analyzer and a high-speed photodetector. The 3-dB bandwidth is measured to be 20 GHz. The eye diagrams at 20 Gb/s show clear eye opening with low jitter. The results indicate that the titanium-doped silicon microring modulator is promising for high-speed optical interconnects.
关键词： high-speed modulation,titanium doping,optical interconnects,silicon photonics,microring modulator
更新于2025-09-23 15:23:52
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Influence of Mg doping on the structural, morphological, optical, thermal, and visible-light responsive antibacterial properties of ZnO nanoparticles synthesized via co-precipitation
摘要： Mg-doped zinc oxide (Zn1-xMgxO, where x = 0.000, 0.001, 0.003, 0.005, and 0.010 M) nanoparticles (MgZnO NPs) were synthesized via a co-precipitation method and subjected to various analyses for application as functional additives in food packaging. The MgZnO NPs were successfully formed at approximately 360 °C and showed an increase in the optical band gap with respect to the increase in the concentration of Mg doping. The X-ray diffraction and scanning electron microscopy analyses of MgZnO NPs confirmed the formation of hexagonal wurtzite structure and rod-like morphology. X-ray photoelectron spectra revealed that the Mg (1s) peaks centered at 1303.35 and 1303.38 eV were ascribed to the presence of Mg2+ replacing Zn2+. Transmission electron microscopy images showed rod shapes with the length of 208–650 nm and width of 84–142 nm. Various concentrations of synthesized MgZnO NPs were investigated against a gram-negative (Escherichia coli - DH5α) bacterial strain under light and dark conditions. Among the studied samples, 0.010 M MgZnO NPs of concentration 3 mg/mL showed the best antibacterial activity under the light condition. MgZnO NPs revealed uneven ridges on the outer surface, which promote the diffusion ability of Zn2+ and increased production of reactive oxygen species, and consequently lead to bacterial lysis. Furthermore, this study demonstrates excellent feasibility for the application of MgZnO NPs as fillers with good antibacterial activity, especially in antimicrobial food packaging applications.
关键词： Mg doping,reactive oxygen species,antibacterial activity,nanorod,ZnO
更新于2025-09-23 15:23:52
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Modulated anodization synthesis of Sn-doped iron oxide with enhanced solar water splitting performance
摘要： Modulated anodization synthesis is introduced here for the fabrication of porous Sn-doped iron oxide. Continuous square-wave modulation consisting of highly positive (+50 to +80 V range) and slightly negative potentials (-2 to -10 V range) at 100 Hz allowed the etching anodization of the metallic Fe foil and incorporation of Sn-dopant from the fluoride anion-containing electrolyte, respectively. Compared with the undoped iron oxide, the surface-enriched Sn-dopant (in the form of Sn4+) alleviates the trapping and recombination of surface holes, while enhancing the hole transfer at the surface states. As such, the overpotential for photoelectrochemical (PEC) water oxidation was reduced by 110 mV and photocurrent density doubled. The incorporation of Co-Pi co-catalyst further improved the hole transfer efficiency, resulting in further reduction in overpotential by another 330 mV with respect to the bare Sn-doped iron oxide and significant improvement in photocurrent density at potentials below +1.23 V vs. reversible hydrogen electrode. Lastly, the iron oxide electrodes exhibit highly stable PEC water oxidation with no degradation in activity throughout the 10 h assessment under simulated solar irradiation and Faradaic efficiency of 90%. We envisage that the modulated anodization technique can be conveniently incorporated for a wide range of other dopants in search of efficient solar water splitting electrodes.
关键词： Doping,Hematite,Hydrogen,Photoelectrochemical water splitting,Charge transport
更新于2025-09-23 15:23:52
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Effect of Er3+-doping on 65GeS2-25Ga2S3-10CsCl glass probed by annihilating positrons
摘要： Effect of Er3+-doping resulting in pronounced mid-IR fluorescence functionality was examined first in chalcohalide 65GeS2-25Ga2S3-10CsCl glass using positron annihilation lifetime (PAL) spectroscopy. The detected PAL spectra were reconstructed from unconstrained x2-term analysis employing two-state simple trapping model for one kind of positron trapping free-volume defects, the parameterization being performed at the example of 65GeS2-25Ga2S3-10CsCl glass doped with 0.6 at. % of Er3+. The observed decrease in positron trapping rate was proved to be primary void-evolution process in this Er-activated glass, like in many other chalcogenide glasses affected by rare earth doping. The nature of this effect was explained in terms of positron trapping reduction model as competitive contribution of changed occupancy sites in Ga-modified glassy matrix available for rare earth ions and annihilating positrons.
关键词： Chalcohalide glass,Positron trapping reduction,Rare earth doping,Photoluminescence
更新于2025-09-23 15:23:52
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Doping induced performance enhancement in inverted small molecule organic photodiodes operating below 1V reverse bias - Towards compatibility with CMOS for imaging applications
摘要： Organic photodiodes (OPDs) offer a myriad of advantages over conventional inorganic photodetectors, making them particularly attractive for imaging application. One of the key challenges preventing their utilization is the need for their integration into the standard CMOS processing. Herein, we report a CMOS-compatible top-illuminated inverted small molecule bi-layer OPD with extremely low dark leakage current. The device utilizes a titanium nitride (TiN) bottom electrode modified by a [6,6]-phenyl C61 butyric acid methyl ester (PCBM) cathode buffer layer (CBL). We systemetically show that doping the CBL enhances device's low voltage (below 1 V reverse bias) photoresponse by increasing the linear dynamic range (LDR) and making the bandwidth of the photodidoe broader without compromising the leakage current. The optimized device exhibits a dark leakage current of only ~ 6 x 10-10 A/cm2 at -0.5 V. The external quantum efficiency (EQE) at 500 nm reaches 23% with a calculated specific detectivity as high as 7.15 x 1012 cm Hz1/2/W (Jones). Also the LDR approaches 140dB and the bandwidth is about 400kHz, at -0.5 V bias. The proposed device structure is fully compatible with CMOS processing and can be integrated onto a CMOS readout circuit offering the potential to be applied in high-performance large-scale imaging arrays.
关键词： Interface engineering,Doping,CMOS,Titanium nitride,Organic photodiode,Cathode buffer layer
更新于2025-09-23 15:23:52
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Synthesis of color-tunable CdTe/CdS:Mn core-shell nanocrystal emitters
摘要： This study presents CdTe/CdS:Mn core–shell nanocrystals (NCs) prepared in aqueous media, using thioglycolic acid as capping agent. Firstly, CdTe NCs were synthesized, and then, Mn-doped CdS shell were deposited on the top of the CdTe core under Ar atmosphere. The NCs were structurally and optically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), X-ray photoelectron (XPS), photoluminescence (PL), and Fourier transform infrared (FTIR) spectroscopy. The results obtained from XRD, XPS, PL, and EDX showed that the Mn ions were successfully introduced into the nanocrystalline shells. Moreover, the effect of Mn concentrations on the optical properties of the synthesized core-shell NCs was investigated. The effective band gap of the sample is in an indirect relationship with the Mn : Cd molar ratio, confirmed by PL analysis, and PL emissions can be measured at various wavelengths. The PL spectra showed 990 and 170 percent enhancement in the emission intensity of CdTe/CdS:Mn core/shell NCs (Mn: Cd 2.5%) compared to CdTe NCs and CdTe/CdS core/shell NCs, respectively. Consequently, the introduction of Mn dopants into the core-shell structures not only diminishes the density of quenching centers, but also reduces the effective band gap energies.
关键词： Core/Shell,Doping,Nanocrystals,CdTe/CdS:Mn,Luminescence
更新于2025-09-23 15:23:52
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How doping configuration affects electron transport in monolayer zigzag graphene nanoribbon
摘要： The electrical conductance of hybrid monolayer graphene/h-BN ribbon with zigzag edges is numerically investigated using density functional theory. Our findings reveal that transmission of graphene/h-BN hybrid structure is sensitive to the arrangement of its component. The result also shows that replacing carbon atoms with boron and nitrogen totally reduces the transmission. Three different arrangement of BN domains have been investigated: replacing carbon atoms with boron and nitrogen in the transport direction, perpendicular to the transport direction and diagonal direction. We find that combination of many factors such as edge effect, additional charge carrier, interface of BN and carbon domains can alter transmission significantly.
关键词： Density functional theory,Doping configuration,Graphene/h-BN hybrid,Electronic transport
更新于2025-09-23 15:23:52
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Phosphorus incorporation into graphitic material via hot pressing of graphite oxide and triphenylphosphine
摘要： It was shown, that the treatment of graphite oxide (GO) at a temperature of 1000 °C and a static pressure of 500 bar recovers the graphene layers. Addition of triphenylphosphine to GO helps in removal of oxygen during the treatment and allows introducing ca. 0.7 at% of phosphorus in the product. Most phosphorus atoms are bonded with oxygen as the 31P nuclear magnetic resonance spectrum showed. An analysis of the X-ray photoelectron P 2p spectrum additionally found the components corresponding to CeP and PeP bonding. Assembling of phosphorus atoms into nanometer clusters was con?rmed by transmission electron microscopy. Raman spectroscopy and electrical conductivity measurements revealed the n-type doping of graphitic material through the incorporation of phosphorus.
关键词： Triphenylphosphine,XPS,Phosphorus doping,NMR,Hot pressing,Graphite oxide
更新于2025-09-23 15:23:52
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Compositional analysis by RBS, XPS and EDX of ZnO:Al,Bi and ZnO:Ga,Bi thin films deposited by d.c. magnetron sputtering
摘要： Rutherford backscattering spectrometry, X-ray photoelectron and X-ray energy dispersive spectroscopies were employed to analyse Bi incorporation into ZnO:Al and ZnO:Ga transparent and electrically conductive thin films deposited by d.c. magnetron sputtering, with thickness in the range of 300–400 nm. Sputtering was performed in an argon atmosphere from two targets in confocal geometry being one composed of either ZnO:Al2O3 or ZnO:Ga2O3 composites and the other a Bi metal target. The content of bismuth dopant in the ZnO matrix was controlled by the respective target current density (JBi) in order to attain a high optical transparency (> 80%) in the visible region. For ZnO:Al,Bi films Bi content varied from 0.1 to a maximum of 1.5 at.% when varying JBi from 0.06 to 0.26 mA cm?2. However, for ZnO:Ga,Bi films, deposited in similar conditions, Bi reached a maximum overall layer content of 2.4 at.%, with a surface enrichment content that varied from 1.3 to 8.8 at.%. It was also observed that the Bi content in the topmost layers of the films is slightly depleted due to thermal evaporation upon thermal annealing in vacuum at 350 °C. It is envisaged applications for these films as transparent photoelectrodes and thermoelectric materials.
关键词： Ga,Bismuth,TCO,Doping,Thermoelectric,Al,XPS,RBS,PIXE,ZnO
更新于2025-09-23 15:23:52