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Synthesis plasmonic Bi/BiVO4 photocatalysts with enhanced photocatalytic activity for degradation of tetracycline (TC)
摘要： In recent years, the excessive use of antibiotics has become a serious problem for human health. BiVO4 regarded as one of the most promising visible-light-driven photocatalysts was used to degrade the antibiotics. In this paper, we fabricated Bi/BiVO4 plasmonic photocatalysts which enhanced the photocatalytic activity of BiVO4 for degradation of tetracycline (TC) antibiotic. The Bi/BiVO4 photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. In addition, the photocatalytic experiment results show that the 0.04-Bi/BiVO4 sample has the best photocatalytic activity for 2 times than the pure BiVO4 photocatalyst. The cycle experiments, after four repetitions of the experiments, showed the sample still maintained a high photocatalytic activity. Finally, the photocatalytic reaction mechanism was also studied by free radical capture experiments and electron paramagnetic resonance spectroscopy.
关键词： Photocatalysts,Tetracycline (TC),Bi/BiVO4,Plasmonic,Visible light
更新于2025-09-12 10:27:22
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Hybridizing engineering strategy of non-lacunary (nBu4N)4W10O32 by carbon quantum dot with remarkably enhanced visible-light-catalytic oxidation performance
摘要： This paper discloses an e?cient strategy for the preparation of carbon quantum dot (CQD)- hybridized (nBu4N)4W10O32 (TBADT). A key step in this strategy is to hydrothermally treat CQD with TBABr solution to form the TBA+ micelle-encapsulated CQD, which acts as a cationized hybridizer to combine with the W10O32 anion to yield the target catalyst. XPS, UV–vis, PL and CV characterizations indicated that CQD hybridizer plays unique roles in improving the structural stability, redox capacity and visible light response of TBADT, especially in enhancing the stability of its photo-excited state. In the visible light-triggered selective oxidation of cyclohexane, toluene, ethylbenzene and benzyl alcohol with dioxygens in acetonitrile, the optimized hybrid containing 3% CQD shows much higher photo-catalytic activity than pure TBADT, a?ording ca. 21.7% conversion and 84.8% cyclohexanone selectivity in cyclohexane photo-oxidation, Additionally, the additive 2 M HCl further enhances the above hybridization e?ects, thereby signi?cantly promoting the current photo-catalytic oxidations.
关键词： Selective oxidation of organic compounds,Hybridizing molecular engineering,Decatungstates,Molecular oxygen,Carbon quantum dot,Visible-light-catalysis
更新于2025-09-12 10:27:22
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Single-Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-promoted Oxidation Reactions
摘要： Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited due to the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for cobalt atom with high atom loadings up to 3.27 wt.%. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while the single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h-1 g-1 via water oxidation, imine formation with high conversion (~90%) and selectivity (>99%), and complete photodegradation of organic dyes.
关键词： single-atom catalysts,oxidation reactions,carbon quantum dots,photocatalysis,visible light
更新于2025-09-12 10:27:22
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Three dimensional Pt island-on-Au architectures coupled with graphite carbon nitride nanosheets for effective photo-accelerated methanol electro-oxidation
摘要： Two dimensional (2D) visible-light-activated graphite carbon nitride (CN) nanosheets were used to deposit the traditional electrocatalyst of Pt and Au through a facile one-pot hydrothermal approach. By adjusting different amount of Pt and Au, 3D Pt island-on-Au architectures were formed on the surface of CN nanosheets (Pt-Au/CN). The obtained Pt-Au/CN composite was used for electrocatalytic methanol oxidation reaction (MOR). Comparing with Pt/CN modified electrode, Pt-Au/CN exhibited 13.8 times enhancement on the electrocatalytic activity of MOR. Interestingly, when Pt-Au/CN composite was illuminated with visible light, the current density and stability were continuously enhanced by evaluating of cyclic voltammetry (CV), chronopoenttiometric (CP), chronoamperometry (CA), and electrochemical impedance spectra (EIS). The bimetallic electronic effects of Pt and Au; 3D Pt islands-on-Au architectures; 2D support nanosheet of CN, and the synergistic effect of photo- and electro-catalytic processes resulted in the improved electrocatalytic activity and stability. The present investigations provide a promising future to construct highly efficient electrocatalyst by combining bimetal on semiconductor support and with the assistance of visible light irradiation.
关键词： visible light,g-C3N4 nanosheet,methanol oxidation,photo-accelerated electrocatlysis,Pt island-on-Au architectures
更新于2025-09-12 10:27:22
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Nanorectenna spectrally-selective plasmonic hot electron response to visible-light lasers
摘要： Active metasurfaces with novel visible and infrared (vis/IR) functionalities represent an exciting, growing area of research. Rectification of vis/IR frequencies would produce needed direct current (DC) with no inherent frequency limitation (e.g., no semiconducting bandgap). However, controlling the materials and functionality of (nano)rectennas for rectifying 100s of THz to the visible regime is a daunting challenge, because of the small features and simultaneously the need to scale up to large sizes in a scalable platform. An active metasurface of a planar array of nanoscale antennas on top of rectifying vertical diodes is a “nanorectenna array” or “microrectenna array” that rectifies very high frequencies in the infrared, or even higher frequencies up to the visible regime. We employ a novel strategy for forming optical nanorectenna arrays using scalable patterning of Au nanowires, demonstrate strong evidence for spectral-selective high-frequency rectification, characteristic of optical antennas. We discover a previously unreported out-of-equilibrium electron energy distribution, i.e. hot electrons arising from plasmonic resonance absorption in an optical antenna characterized by an effective temperature, and how this effect can significantly impact the observed rectification.
关键词： nanorectenna,spectrally-selective,hot electron,plasmonic,visible-light lasers
更新于2025-09-12 10:27:22
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Gastroscopy assisted laser Doppler flowmetry and visible light spectroscopy in patients with chronic mesenteric ischemia
摘要： Mucosal pathology due to chronic mesenteric ischemia (CMI) is rarely seen during upper endoscopy. Combining Laser Doppler Flowmetry (LDF) and Visible Light Spectroscopy (VLS) may aid in detection of CMI at an early stage. We aimed to investigate the utility of LDF and VLS in detecting microcirculatory changes in patients with CMI during upper endoscopy. In a single center, prospective study, 104 patients were evaluated for mesenteric ischemia during a 24 months period. Patients with a consensus diagnosis of CMI (n ? 40) were examined with LDF and VLS. Thirty-two were successfully treated and had a definitive diagnosis of CMI. Results were compared with controls (n ? 38) with normal intestinal circulation evaluated with duplex ultrasonography (DUS). Treatment response was evaluated clinically and with DUS at 1 month and with VLS and LDF at 3 months. A significant reduction in mucosal capillary hemoglobin oxygen saturation (SO2) was found in CMI patients compared to controls before treatment: mean ± SD: 67 ± 9%, 81 ± 4%, respectively (p < .001). A significant reduction was also seen for the relative hemoglobin (rHb) amount, flow and velocity (p < .001). The sensitivity of SO2 measured by VLS for diagnosing CMI was 94% and the specificity 72% (cut-off 78%), calculated with ROC curve analysis. A combination of SO2 and rHb increased the test sensitivity and specificity to 97% and 79%, respectively. Conclusion: CMI patients have significantly reduced microcirculation in the stomach and duodenum compared to controls. The results suggest that VLS should be included when performing an upper endoscopy in patients with suspected CMI.
关键词： laser doppler flowmetry,acute mesenteric ischemia,Chronic mesenteric ischemia,upper endoscopy,visible light spectroscopy
更新于2025-09-12 10:27:22
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[IEEE 2019 15th International Conference on Telecommunications (ConTEL) - Graz, Austria (2019.7.3-2019.7.5)] 2019 15th International Conference on Telecommunications (ConTEL) - A Flexible OLED based VLC Link with m-CAP Modulation
摘要： In recent years there has been a growing interest in using organic light emitting diodes (OLEDs) for illumination in indoor environments. They offer attractive features such as flexibility and large active areas at a low cost; they are energy efficient and have higher illumination levels compared to silicone based LEDs. In addition, the utilization of OLEDs have increased in devices such as smart mobile phones and TVs because of their low thickness. This paper investigates the performance of an OLED based visible light communications (OVLC) system, using a curved and flat OLED with multiband carrierless amplitude and phase (m-CAP) modulation for m = 2 at different angles of incidence on the optical receiver. It is shown that the BER performance is improved (i.e., below the forward error correction (FEC) limit of 3.8×10-3) with the curved OLED when the optical receiver moving along a circular path for the viewing angles greater 40o compared to the flat OLED, which is advantageous in device to device communications.
关键词： m-CAP modulation,flexible organic LEDs,visible light communications
更新于2025-09-12 10:27:22
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Integrated color photodetectors in 40 nm standard CMOS technology
摘要： For the further integration of receivers in multi-color visible light communication systems, a novel color photodetector (PD) was designed and fabricated by using a 40 nm standard complementary metal oxide semiconductor (CMOS) process without any process modifications. The PD consists of CMOS photodiode and two-dimensional (2D) polysilicon subwavelength grating above the photodiode. The 2D polysilicon grating is controlled in structural parameters to realize color filtering, based on guided-mode resonance, for the first time in a standard CMOS process. Here three kinds of color PDs were designed to respond to the three primary colors. The measured results demonstrate that the color PDs exhibit wavelength selectivity in the visible range (400-700 nm) and the maximum peaks in the spectral response curves of them are at 660 nm (red), 585 nm (green) and 465 nm (blue), respectively. In addition, the added 2D polysilicon grating almost does not reduce the responsivity of the photodiodes.
关键词： two-dimensional polysilicon subwavelength grating,Color photodetector,visible light communication,complementary metal oxide semiconductor (CMOS)
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Wireless Communications and Networking Conference (WCNC) - Marrakesh, Morocco (2019.4.15-2019.4.18)] 2019 IEEE Wireless Communications and Networking Conference (WCNC) - A Robust and Energy Efficient NOMA-Enabled Hybrid VLC/RF Wireless Network
摘要： The present work investigates the performance of non-orthogonal multiple access (NOMA) in a hybrid visible light communication (VLC)/radio frequency (RF) wireless network. In particular, we investigate the energy efficiency of the proposed architecture assuming imperfect channel state information (CSI), which is a realistic assumption that is encountered in practical indoor and outdoor wireless communication scenarios. We demonstrate that the performance of the proposed scheme in terms of energy efficiency outperforms by four-fold the corresponding performance of its orthogonal frequency division multiple access (OFDMA) counterpart. In addition, it is shown that the energy efficiency of the proposed scheme is more robust to CSI errors and line of sight (LOS) variations than the OFDMA-based scheme, which appears to be more susceptible to the CSI error and the LOS availability probability. Finally, our findings reveal that the performance gain of NOMA over OFDMA in the considered hybrid VLC/RF setup is directly proportional to the probability of LOS availability. These results are expected to be useful in the efficient design and efficient operation of hybrid VLC/RF wireless systems.
关键词： Non-orthogonal multiple access (NOMA),Energy efficiency,Channel state information (CSI),Radio frequency (RF),Visible light communication (VLC),Hybrid wireless network
更新于2025-09-12 10:27:22
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Performance of Indoor Visible Light Communication System Under Random Placement of LEDs
摘要： In this paper, the performance of indoor visible light communication (VLC) system with randomly deployed light-emitting-diodes (LED) using Matern hardcore point process (MHCP) is analyzed and compared with existing random geometries like binomial point process (BPP) and fixed geometries such as circular and square. It is well known fact that the signal-to-noise-ratio (SNR) profile inside the room changes with respect to LED placement as well as receiver’s position. In order to achieve uniform SNR across the room, the proposed work uses MHCP based LED placement at the transmitter and a single photodiode (PD) at the receiver. Simulation results show that random placement of LED using MHCP configuration results in a much more uniform SNR profile inside the room than the random BPP and conventional circular and square LED placements. Further, our results also show that by deploying MHCP based LED placement, the average SNR across the room increases.
关键词： uniform signal-to-noise-ratio,Matern hardcore point process,visible light communications
更新于2025-09-12 10:27:22