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- 2018
- imgae sensor
- internet of things
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- Signal-to-Noise Ratio (SNR)
- Infinite Gain Multiple Feedback (IGMF)
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Preparation of interstitial carbon doped BiOI for enhanced performance in photocatalytic nitrogen fixation and methyl orange degradation
摘要： Carbon-doped BiOI (C-BiOI) photocatalysts were successfully synthesized via a hydrothermal method with Bi(NO3)3·5H2O, KI, and glucose as raw materials for the first time. The synthesized samples had excellent photocatalytic activities in the degradation of methyl orange (MO) and the reduction of N2 to NH3. To reveal the origin of the superior photoactivity, the C-BiOI was examined by multi techniques, including N2-adsorption, XRD, SEM, TEM, Raman, XPS, DRS, PL, EIS and transient photocurrent response. The characterization results indicated that the carbon clusters entered the interlayers of BiOI crystal during preparation. The doped carbon interfered the lattice periodicity and generated vacancies in the BiOI structure, resulting in the decreased band gap and increased efficiency in charge separation, both of which could significantly hasten the photocatalytic reaction. Additionally, the introduced carbon affected the morphology of BiOI and increased its specific surface area, which may also benefit the photocatalytic process. The carbon content was crucial to the promotion effect. Under visible light, the optimized carbon-doped BiOI (C-BiOI-2) presented an MO degradation rate of 0.136 min-1, which was 4.44 times higher than that of pure BiOI. However, for the photocatalytic N2 fixation, due to the contribution of surface carbon in N2 adsorption, the C-BiOI sample containing higher carbon content (C-BiOI-3) displayed superior performance than C-BiOI-2. The NH3 generation rate under simulated sunlight reached 311 μmol g?1h?1, which was about 3.7-fold of that of BiOI. This work may shed some insight into the designing and understanding of carbon-doped semiconductor photocatalysts.
关键词： interstitial doping,C-BiOI,photocatalytic N2 fixation,visible light
更新于2025-09-23 15:23:52
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Effect of Hydration Procedure of Fumed Silica Precursor on the Formation of Luminescent Carbon Centers in SiO <sub/>2</sub> :C Nanocomposites
摘要： The effect of hydration procedure of fumed silica precursor on photoluminescent properties of carbonized silica (SiO2:C) nanocomposite after chemo/thermal treatments is studied. Main structural effect is the formation of chemical bonding of phenyl groups to silica surface via multiple C─Si─O bonding bridges. Synthesized samples demonstrate very broad photoluminescence (PL) bands in near ultraviolet and visible ranges with maximum intensity dependent on temperature of thermal annealing. Two main trends in luminescence properties are: 1) hydration-induced blue shift of PL in comparison with PL of unhydrated series; 2) red shift of PL bands with increasing synthesis temperature regardless hydration procedure. Temperature dependent evolution of light emission bands is discussed in terms of surface carbon nanoclusters formation and aggregation processes. It is assumed that blue shift of PL bands in the hydrated series is associated with the decreased surface mobility of carbon atoms and clusters as a result of increased chemical bonding with silica surface that slows down carbon thermally stimulated clusterization/aggregation processes.
关键词： carbonized nanocomposite material,carbonized fumed silica,phenyltrimethoxysilane,wide-band visible photoluminescence,carbon clusters
更新于2025-09-23 15:23:52
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[Lecture Notes in Computer Science] Distributed Computing and Internet Technology Volume 11319 (15th International Conference, ICDCIT 2019, Bhubaneswar, India, January 10–13, 2019, Proceedings) || Improved Visible Light Communication Using Code Shift Keying Modulation
摘要： Visible light communication can provide higher bandwidth and bit rates without causing any interference to the Radio Frequency signals. Red-Green-Blue Light-Emitting Diodes are more suitable than other light sources as they have a smaller switching time, greater lifespan and cost-effective. Designing a communication scheme that avoids dimming and flickering, and that maximize the throughput and coverage area is challenging. Modulation schemes such as Amplitude Shift Keying, Frequency Shift Keying, and Phase Shift Keying exist in the literature for communication with controlled dimming and flickering effect. However, these schemes may not be efficient as they bound the bit rates with more Bit Error Rate. In this paper, a spread spectrum technique, Code Shift Keying along with Manchester (CSK-M) coding, is used to improve bit rates, a reduction in Bit Error Rate with an efficient control of fluctuations and dimming effect. The simulation results show that the presented approach outperforms the existing modulation schemes.
关键词： Visible light communication,Dimming,Bit rate,BER,CSK-M
更新于2025-09-23 15:23:52
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Facile green synthesis of Degraded-PVA coated TiO2 nanoparticles with enhanced photocatalytic activity under visible light
摘要： Grafting with conjugated structures has been proven to be an effective strategy to enhance the visible-light photocatalytic activity of TiO2, however, the preparation of conjugated structures modified TiO2 nanoparticles usually involves several tedious treatment steps and large amounts of organic solvents. In this research, a facile and green method to synthesize Degraded-PVA coated TiO2 (TiO2@D-PVA) nanoparticles containing conjugated structures was prepared. This method avoided using organic solvents and successfully coated D-PVA onto the surface of TiO2 just via physical mixing, centrifugation, and calcination. In addition, the content of D-PVA in TiO2@D-PVA could be controlled by the concentration of the PVA solution. Under visible light irradiation, the TiO2@D-PVA containing approximately 5 wt% D-PVA demonstrated an optimal photocatalytic activity which is 5.5 times higher than that of commercial P25 TiO2 nanoparticles. The Ti-O-C bonds and the conjugated structures in D-PVA could facilitate the electron transfer between D-PVA and TiO2, thus contributing to the enhanced visible light photocatalytic activity.
关键词： TiO2,photocatalytic activity,PVA,visible light
更新于2025-09-23 15:23:52
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UV and visible-light driven photocatalytic removal of caffeine using ZnO modified with different noble metals (Pt, Ag and Au)
摘要： In this work, ZnO photocatalyst was modified with different noble metals (Pt, Ag and Au) through photo-deposition method and then characterized by different techniques (XRD, XRF, BET, UV–vis DRS, FESEM, and XPS). The addition of noble metals produces important changes in the light absorption properties with a significant absorbance in the visible region due to the existence of surface plasmon resonance (SPR) observed at about 450 nm and 550 nm for ZnO modified with Ag and Au, respectively. The morphology of the samples was studied by TEM and the size ranges of the different metals were estimated. Noble metal nanoparticles were in every case heterogeneously deposited on the larger ZnO particles. All the prepared photocatalysts were tested in the photocatalytic removal of caffeine (toxic and persistent emerging compound) under UV and visible light irradiation. It was observed an enhancement of photocatalytic caffeine removal from aqueous solutions under UV light irradiation with the increase of metal content (from 0.5 to 1 wt %) for ZnO modified with Ag and Au (Ag/ZnO and Au/ZnO). In particular, Ag/ZnO and Au/ZnO with higher Ag and Au content (1 wt %) allowed to achieve the almost complete caffeine degradation after only 30 min and a TOC removal higher than 90% after 4 h of UV light irradiation. These two photocatalysts were investigated also under visible light irradiation and it was found that their photocatalytic performances were strongly enhanced in presence of visible light compared to unmodified ZnO. In particular, Ag/ZnO photocatalyst was able to reach the complete caffeine degradation and a TOC removal of about 70% after 4 h of visible light irradiation.
关键词： Caffeine removal,Photocatalysis,ZnO,UV and visible light,Noble metals
更新于2025-09-23 15:23:52
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Confining analyte droplets on visible Si pillars for improving reproducibility and sensitivity of SALDI-TOF MS
摘要： We present a universal method to efficiently improve reproducibility and sensitivity of surface-assisted laser desorption/ionization time of flight mass spectrometry (SALDI-TOF MS). In this method, the Si pillar array with unique surface wettability is used as substrate for ionizing analyte. The Si pillar is fabricated based on the combination of photolithography and metal-assisted chemical etching, which is of hydrophilic top and hydrophobic bottom and side wall. Based on the surface wettability of the Si pillar, a droplet of an aqueous analyte solution can be confined on the top of the Si pillar. After evaporation of solvent, an analyte deposition spot is formed on the top of Si pillar. The visible size of the Si pillar allows the sample spot to be easily found. Meanwhile, the diameter of the Si pillar is smaller than that of the laser, allowing the observation of all analyte molecules under one laser shot. Therefore, the reproducibility and sensitivity are highly improved with this method, which allows for the quantitative analysis. Furthermore, this method is applicable for different analytes dissolved in water, including amino acids, dye molecules, polypeptides, and polymers. The application of this substrate is demonstrated by analyzing real samples at low concentration. It should be a promising method for sensitive and reproducible detection for SALDI-TOF MS.
关键词： Improving reproducibility and sensitivity,SALDI-TOF MS,Visible Si pillars,Minimizing sample spots,Universality
更新于2025-09-23 15:23:52
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Benthic microbial fuel cell equipped with a photocatalytic Cu2O-coated cathode
摘要： In this study, a photocatalytic benthic microbial fuel cell was developed and the cell performance was tested. A photocathode was fabricated by electrodeposition of Cu2O photocatalysts on carbon felt; with a proper deposition time of 15 min, a photocathode with optimal Cu2O compactness and an average Cu2O particle size of 0.97 μm was fabricated and was then covered with an amorphous carbon thin layer. Photoelectrochemical test results prove the pronounced visible light response of the fabricated photocathode. Results show that the coating of carbon thin layer could protect the Cu2O from self-reduction and also improve the photoelectrochemical performance of Cu2O crystalline grains. The photo-benthic microbial fuel cell (BMFC) produces a maximum power density of 249.0 mW m ? 2 and 186.7 mW m?2 under light irradiation and in the dark, which is 17.8 and 13.3 times higher than the common BMFC using carbon felt cathode in parallel, demonstrating the catalytic and photocatalytic effect of the fabricated photocathode. Polarization and EIS results prove the decrease of internal resistance by using the photocathode. The fabricated photocathode could improve the oxygen reduction rate on the cathode side, thus reduce the internal resistance and enhance the BMFC performance.
关键词： Benthic microbial fuel cells,Photocathode,Nanostructured catalyst,Visible light,Cu2O
更新于2025-09-23 15:23:52
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Revealing the role of kapok fibre as bio-template for In-situ construction of C-doped g-C3N4@C, N co-doped TiO2 core-shell heterojunction photocatalyst and its photocatalytic hydrogen production performance
摘要： For the first time, C-doped g-C3N4@C, N co-doped TiO2 core-shell heterojunction photocatalyst was successfully prepared by an in-situ one-pot hydrothermal bio-template approach, assisted by calcination treatment at 500?°C. Kapok fibre was used as a bio-templates and in-situ C doping in g-C3N4 and TiO2 during the formation of core-shell heterojunction photocatalyst. Moreover, the used of urea as g-C3N4-precursor also contribute to band-gap narrowing by an in-situ carbon and nitrogen doping in TiO2. Various characterisation techniques were employed to understand the effect TiO2 precursor concentration on the evolution of core-shell nanostructure heterojunction photocatalyst that can affect and boost the catalytic activity. The detailed understanding of the concurrent growth of C-doped g-C3N4 (CCN) and C, N co-doped TiO2 mechanism, as well as the formation of core-shell nanostructures heterojunction formation, are also proposed in this study. Our finding indicated that the bio-template core-shell nanostructure heterojunction photocatalysts showed a dramatic increase in photoinduced electron-hole separation efficiency as demonstrated by the photoelectrochemical and photoluminescence analyses. The enhancement in photogenerated charge carrier separation and narrower band gap resulted in superior photocatalytic activities with the highest rate of hydrogen production was recorded by CCN/T-1.5 sample (625.5 μmol h-1 g-1) in methanol aqueous solution. The well-developed interconnected heterojunction formation with appropriate CCN and TiO2 contents in core-shell nanoarchitectures system is a prime factor for the future design of a highly efficient visible-light-driven photocatalyst.
关键词： Bio-template,Heterojunction photocatalyst,Core-shell,Co-doping,Photocatalytic hydrogen production,Visible light
更新于2025-09-23 15:23:52
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A novel P-doped Fe2O3-TiO2 mixed oxide: Synthesis, characterization and photocatalytic activity under visible radiation
摘要： In this work, a novel P-doped Fe2O3-TiO2 mixed oxide was successfully prepared by a microwave assisted sol-gel method. The synthesized catalyst was characterized by N2 physisorption, SEM, XRD, XPS, and FTIR, UV–vis DRS, and PL spectroscopies. The iron and phosphorus content in the catalyst samples were quanti?ed by AAS and ICP-OES, respectively. The photocatalytic activity of P-doped Fe2O3-TiO2 powders were evaluated in the photocatalytic degradation of sulfamethazine (SMTZ). The Box Behnken design (BBD) and response surface methodology (RSM) were applied for modeling the e?ect and optimizing of the operational parameters levels on the degradation percentage of SMTZ. The complete degradation and mineralization percentage of 30% of SMTZ solution at pH 9 was achieved within 300 min of reaction, with the optimum P doping amount of 1.2 wt % and 1.25 g/L of catalyst loading. The 1.2 wt % P-doped Fe2O3-TiO2 mixed oxide showed considerably higher photocatalytic activity than Fe2O3-TiO2 or TiO2. This enhanced performance could be attributed to the small crystallite size, narrow band gap, high speci?c surface area and increased number of surface hydroxyls on TiO2 nanoparticles. Additionally, the stability and reusability of this catalyst was demonstrated during three cycles of SMTZ degradation.
关键词： Enhanced surface area,Visible light activation,Box behnken design,Reusability,P-doped Fe2O3-TiO2 mixed oxide
更新于2025-09-23 15:23:52
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Novel emission bands of Na2TiF6:Mn4+ phosphors induced by the cation exchange method
摘要： A series of Na2TiF6:xMn4+ samples were prepared by the cation exchange method. Visible QC behavior and the strongest ZPL peaks were observed for these samples. The characteristic of the visible QC behavior is that PL intensity at 620 nm is 1.61 times as high as PLE intensity at 476 nm. The mechanisms of these phenomena were discussed, and the color purity, crystal-field and nephelauxetic effect, the critical distance and the multipolar interaction for the samples were determined. The result shows that the Mn4+ ions are located at a strong crystal field and the concentration quenching of Mn4+ is from the quadrupole-quadrupole interaction. The slightly increase of nephelauxetic ratio causes the slightly blue shift of emission. The color-purity and chromaticity coordinates of the optimal sample suggests that the strongest ZPL makes its red emission with high color-purity. Thus, Na2TiF6:0.08Mn4+ is a potential red-emitting phosphor for blue light-based WLEDs.
关键词： Fluorides,Photoluminescence,Mn4+,Red emitting phosphor,Visible quantum cutting
更新于2025-09-23 15:23:52