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Mg Doped Perovskite LaNiO <sub/>3</sub> Nanofibers as an Efficient Bifunctional Catalyst for Rechargeable Zinc–Air Batteries
摘要： Rational design of efficient and durable bifunctional catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is important for rechargeable zinc-air batteries. Herein, Mg doped perovskite LaNiO3 (LNO) nanofibers (LNMO NFs) were prepared by a facile electrospinning method combined with subsequent calcination. LNMO NFs show a more positive half-wave potential of 0.69V and a lower overpotential of 0.45 V at a current density of 10 mA cm-2 than those of the pristine LNO NFs. As an air electrode for zinc-air battery, the cell with LaNi0.85Mg0.15O3 NFs catalyst is able to deliver a high specific capacity of 809.9 mAh g-1 at a current density of 5 mA cm-2. It also shows an excellent cycling stability over 110 h at a current density of 10 mA cm?2. DFT calculation results demonstrate that the LNMO surface binds oxygen stronger than LNO, which contributes to enhanced OER activity as observed in our experiments. The results indicate that LNMO NFs is an efficient and durable bifunctional catalyst for zinc-air batteries.
关键词： bi-functional catalyst,Mg doped LaNiO3 nanofibers,electrospinning,density functional theory calculation,zinc-air batteries
更新于2025-11-14 17:04:02
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Origin of Ferroelectricity in Epitaxial Si-doped HfO2 Films
摘要： HfO2-based unconventional ferroelectric (FE) materials were recently discovered and have attracted a great deal of attention in both academia and industry. The growth of epitaxial Si-doped HfO2 films has opened up a route to understand the mechanism of ferroelectricity. Here, we used pulsed laser deposition (PLD) to grow epitaxial Si-doped HfO2 films in different orientations of N-type SrTiO3 substrates. Using piezoforce microscopy, polar nanodomains can be written and read, and these domains are reversibly switched with a phase change of 180o. Films with different thicknesses displayed a coercive field Ec and a remnant polarization Pr of approximately 4～5 MV/cm and 8～32 μC/cm2, respectively. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results identified that the as-grown Si-doped HfO2 films have strained fluorite structures. The ABAB stacking mode of the Hf atomic grid observed by HRTEM clearly demonstrates that the ferroelectricity originates from the noncentrosymmetric Pca21 polar structure. Combined with soft X-ray absorption spectra (XAS), it was found that the Pca21 ferroelectric crystal structure manifested as O sublattice distortion by the effect of interface strain and Si dopant interactions, resulting in further crystal-field splitting as a nanoscaled ferroelectric ordered state.
关键词： HRTEM,PLD,XRD,Ferroelectricity,PFM,XAS,Epitaxial Si-doped HfO2 thin films,N-type SrTiO3 substrates
更新于2025-11-14 17:04:02
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Sulfur doped carbon nitride quantum dots with efficient fluorescent property and their application for bioimaging
摘要： Heteroatom doping can drastically alter electronic characteristics of carbon nitride quantum dots, thus resulting in unusual properties and related applications. Herein, we used sulfur as the doping element and investigated the influence of doping on the electronic distribution of carbon nitride and the corresponding fluorescent property. A simple synthetic strategy was applied to prepare sulfur-doped carbon nitride (S-g-C3N4) quantum dots through ultrasonic treatment of bulk S-g-C3N4. Characterization results demonstrated that the prepared S-g-C3N4 quantum dots with an average size of 2.0 nm were successfully prepared. Fluorescent properties indicated that S-g-C3N4 quantum dots have an emission peak at 460 nm and cover the emission spectra region up to 550 nm. Furthermore, the fluorescent intensity is greatly increased due to the sonication of bulk S-g-C3N4 into quantum dots. As a result, S-g-C3N4 quantum dots not only show a blue cell imaging, but have a bright green color. Therefore, S-g-C3N4 quantum dot is a promising candidate for bioimaging benefiting from the efficient fluorescent property, good biocompatibility, and low toxicity.
关键词： Doped carbon nitride,Fluorescent property,In vitro cytotoxicity,Quantum dots,Bioimaging
更新于2025-11-14 17:04:02
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Carbon Black and Titanium Interlayers Between Zinc Oxide Photo Electrode and Fluorine-Doped Tin Oxide for Dye-Sensitized Solar Cells
摘要： Carbon black and titanium interlayers were deposited on ?uorine-doped tin oxide (FTO) anode layers using radio frequency magnetron sputtering method. On top of them, Zinc oxide (ZnO) photo anode layers were prepared using plasma enhanced chemical vapor deposition technique. ZnO high binding energy as well as good breakdown strength, cohesion, and stability used as a photo electrode material for dye-sensitized solar cells (DSSC), but it does not have a good electrical contact to the FTO anode. To solve this problem, the carbon black and titanium interlayers were deposited. The effect of interlayers on the power conversion ef?ciency (PCE) of DSSCs was investigated. The PCE of the devices with 120-nm-thick interlayers of carbon black or titanium was 5.21 or 4.45%, respectively, which were larger than the PCE of the devices without such interlayers (3.25%). The smooth interface of the carbon black interlayer reduced the interface impedance of the ZnO photo anode effectively. On the other hand, the titanium interlayer with TiO2 on the ZnO side increased the impedance, and decreased the PCE.
关键词： Fluorine-Doped Tin Oxide,Titanium,Carbon Black,Dye-Sensitized Solar Cells
更新于2025-11-14 17:04:02
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Efficient Dye-Sensitized Solar Cells Composed of Nanostructural ZnO Doped with Ti
摘要： Photoanode materials with optimized particle sizes, excellent surface area and dye loading capability are preferred in good-performance dye sensitized solar cells. Herein, we report on an efficient dye-sensitized mesoporous photoanode of Ti doped zinc oxide (Ti-ZnO) through a facile hydrothermal method. The crystallinity, morphology, surface area, optical and electrochemical properties of the Ti-ZnO were investigated using X-ray photoelectron spectroscopy, transmission electron microscopy and X-ray diffraction. It was observed that Ti-ZnO nanoparticles with a high surface area of 131.85 m2 g?1 and a controlled band gap, exhibited considerably increased light harvesting efficiency, dye loading capability, and achieved comparable solar cell performance at a typical nanocrystalline ZnO photoanode.
关键词： bandgap energy,dye-sensitized solar cell,photovoltaic performance,Ti doped ZnO
更新于2025-11-14 17:04:02
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Determination of Thiourea by On–Off Fluorescence Using Nitrogen-Doped Graphene Quantum Dots
摘要： A thiourea-detecting fluorescence sensor with Hg2t as a switch was developed using nitrogen-doped graphene quantum dots (N-GQDs). The surface of N-GQDs had many organic functional groups on which Hg2t was effectively bound and turned off the fluorescence of the N-GQDs. The fluorescence of N-GQDs was turned on by the thiol functional group of thiourea that bound strongly with Hg2t and formed Hg2t/thiourea complexes. After constructing the sensor, the experimental conditions and parameters, such as the pH and Hg2t concentration, were investigated and optimized. Under the optimum conditions, the constructed fluorescence sensor showed high sensitivity to thiourea at concentrations from 0.5 to 14 mM with a low detection limit of 41.7 nM. The sensor also exhibited high specificity, excellent stability, and good reproducibility so that the determination of thiourea in various samples had acceptable values with good recoveries from 99% to 106%. The relative standard deviation was less than 4.1% (n ? 3).
关键词： thiourea,Fluorescence,nitrogen-doped graphene quantum dots (N-GQDs),Hg2t,sensor
更新于2025-11-14 17:04:02
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Aggregation-induced phosphorescence quenching method for the detection of picric acid based on melamine-passivated Mn-doped ZnS quantum dots
摘要： Melamine (MA)-passivated Mn-doped ZnS quantum dots (QDs) were synthesized by a hydrothermal method. The MA-passivated QDs can form a charge-transfer complex with picric acid (PA) at 80 °C, thereby quenching the phosphorescence of the QDs. A sensitive method for detecting PA was established based on this principle of phosphorescence quenching. When the PA concentration ranged from 2.0–180 ng mL–1, the concentration was linearly related to the quenching intensity of the QDs, with a detection limit of 1.4 ng mL–1. When applied to detect PA in environmental water samples, the proposed method showed superior analytical performance compared with other PA analysis methods. Furthermore, we verified the static quenching mechanism by density functional theory. MA on the surface of QDs and PA formed a stable structure with a binding energy of 12.43 eV.
关键词： Melamine,Picric Acid,Mn-doped quantum dots,Charge-transfer Complex,Phosphorescence
更新于2025-11-14 17:04:02
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Enhanced photoelectrochemical performance of Zn2SnO4N by interstitial N induced the build-in polarization electric field
摘要： Highly active Zn2SnO4N photocatalysts were successfully prepared by the one-step microwave-assisted solvothermal method. N heteroatoms were introduced into Zn2SnO4 by occupying the interstitial sites, inducing the formation of the build-in polarization electric field and the impurity level which was advantageous to promote the separation and the migration of photoinduced electron-hole pairs. As a result, the as-prepared Zn2SnO4N exhibited improved the photoelectrochemical properties and the photodegradation rate of RhB over Zn2SnO4N had been demonstrated to increase 3.3 times compared to that of pure Zn2SnO4. Under the effect of the built-in electric field, the impurity level served as a springboard for electron transition rather than a recombination center, which caused the enhancing photocatalytic performance. The finding may provide a new insight into understanding the mechanism of doping modification.
关键词： N-doped,Zn2SnO4,Build-in electric field,Photocatalysis,Impurity level
更新于2025-11-14 17:04:02
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Ellipsometric study on optical properties of hydrogen plasma-treated aluminum-doped ZnO thin film
摘要： Aluminum-doped zinc oxide (AZO) thin films were prepared by radio frequency (RF) sputtering at room temperature, and then post-treated by hydrogen (H2) plasma at different durations. After H2 plasma treatment under the condition of 10 W, 200 °C and 3.0 Hours, the resistivity showed a dramatically decrease from 1.6 Ω cm to 3.4 × 10?3 Ω cm, while the transmittance at the wavelength of 550 nm was improved from 90.5% to 96.0%. The optical constants of H2 plasma-treated AZO thin films were detailed characterized by a varied angle spectroscopic ellipsometer. The results show that the refractive index n decreases in the entire measured wavelength range of 350–1100 nm, while the extinction coefficient k decreases in the short wavelength range and changes negligibly at the long wavelength range. These results can provide guidelines for the design and optimization of AZO thin film-based optoelectronic applications.
关键词： Resistivity,Spectroscopic ellipsometer,Transmittance,Optical constants,Hydrogen plasma treatment,Aluminum-doped zinc oxide
更新于2025-11-14 17:03:37
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A microfluidic all-vanadium photoelectrochemical cell with the N-doped TiO2 photoanode for enhancing the solar energy storage
摘要： In this work, the nitrogen-doped TiO2 photocatalyst is synthesized and applied in a microfluidic all-vanadium photoelectrochemical cell for enhancing the solar energy storage. The use of the nitrogen-doped TiO2 photoanode and the minimization design can ensure the visible-light response, increased specific surface area, vigorous pore structure and enhanced photon and mass transport as well as more uniform light distribution. Various characterizations are performed to evaluate the developed photocatalyst and microfluidic all-vanadium photoelectrochemical cell. The results confirm that the developed nitrogen-doped TiO2 photoanode can provide both the extended absorption spectrum and the small anatase crystal size as well as the obviously enlarged specific surface area with plentiful pore structure. Because of these merits, the microfluidic all-vanadium photoelectrochemical cell with the nitrogen-doped TiO2 photoanode yield the average photocurrent density of 0.103 mA/cm2 during the long-term operation, which is much higher than those with the un-doped TiO2 photoanode (0.086 mA/cm2) and commercial P25 TiO2 photoanode (0.073 mA/cm2), presenting 19.8% and 41% improvements, respectively. The results demonstrate not only the promotion of the vanadium reversible redox pairs conversion but also the inherently excellent stability by the nitrogen-doped TiO2 photoanode.
关键词： Photoanode,N-doped TiO2 photocatalyst,Conversion rate,Microfluidic all-vanadium photoelectrochemical cell,Solar energy storage
更新于2025-11-14 17:03:37