Optimal Doping Ratio Research Articles

Synthesis and characteristics of BaYF5:Yb3+, Er3+@BaYF5 nanoparticles as a new near-infrared fluorescence bioimaging probe

Fluorescent bioimaging technology has been widely used in clinic because of its high sensitivity, quick feedback, and no radiation. Among them, NIR-II imaging has lower absorption, tissue scattering, self-fluorescence, and higher signal-to-noise ratio. As a precursor of nanoprobe, BaYF5 is an excellent material due to its low phonon energy, which makes it easy to achieve rare earth ion energy level transition and obtain strong upconversion luminescence. A near-infrared II (NIR-II) rare earth fluoride nanoparticle (NP) BaYF5 : Yb3 + , Er3 + @ BaYF5 has been constructed. The luminescence principle of the material was deeply analyzed, and the influence of different doping ion ratio on fluorescence intensity was explored. Finally, the optimal doping ratio for this matrix material was obtained. In addition, according to the surface properties of the materials, the water solubility and biocompatibility of the NPs were significantly improved by the modification. Our work also systematically tested and analyzed the cytotoxicity, hematotoxicity, and tissue toxicity of the NPs and finally realized the high-resolution fluorescence imaging in living mice. This NP can be used as an effective and safe NIR-II contrastive agent, which provides the possibility for the detection and monitoring of physiological activity under deep tissue in vivo.

Rapid Ferroelectric-Photoexcited Bacteria-Killing of Bi4Ti3O12/Ti3C2T x Nanofiber Membranes.

The online version contains supplementary material available at 10.1007/s42765-022-00234-8.

Enhancing Zn–CO2 battery with a facile Pd doped perovskite cathode for efficient CO2 to CO conversion

Using aqueous Zn–CO2 batteries to store renewable energy and produce valuable chemicals using CO2 as the source is a promising method for CO2 mitigation, that is alternative to traditional energy-costing CO2 capture/storage technologies. However, the lack of efficient CO2-reduction catalysts significantly hinders the efficiency of such batteries. In this study, an efficient perovskite cathode, Pd-doped La2CuO4, was successfully developed for the cathodic CO2 reduction reaction (CO2RR), and the optimal doping ratio of La2Cu1-xPdxO4 (x = 0.05) was determined. Compared with the pristine La2CuO4 catalyst, the current density for the CO2RR in the H-cell and the Faraday efficiency of CO production are both increased by ∼50% when operated −1.0 V (vs RHE). As a result, the peak power density of a Zn–CO2 battery using the Pd-doped La2CuO4 catalyst reached 0.75 mW cm−2 at 2.23 mA cm−2 by an enhancement ratio of 25%. Density functional theory calculations revealed that the *CO desorption processes on the cathode were enhanced owing to Pd doping, which accounted for the enhanced CO2RR activity and selectivity. The findings of this study show the potential application of perovskite catalysts in the cathode of Zn–CO2 batteries and provide an effective method for battery performance enhancement via the facile Pd doping.

Effect of cobalt doping on the photocatalytic performance of AgInS2 for organic pollutant degradation and hydrogen production

In this work, AgInS2 (AIS) and cobalt (Co) doped AgInS2 (Co-AIS) are prepared by low-temperature liquid phase method using thioglycolic acid (TGA) as the stabilizing agent. The crystal structure, surface elements, binding energy, particle morphology, and optical properties of AIS and Co-AIS are analyzed by XRD, XPS, SEM, TEM, UV-Vis-DRS, and PL. Rhodamine B (RhB) and 4-nitrophenol (4-NP) are used as the model pollutants for evaluating the photocatalytic activities of AIS and Co-AIS. The optimal doping ratio of CoːIn is found to be 10.7:6.3. And, under this optimal ratio, Co-AIS can degrade 95 % of RhB in 1.5 h or 76 % of 4-NP in 2.5 h, respectively. The photocatalytic mechanism is proposed based on the active species trapping experiment, EPR technique, optical properties characterization, and the flat-band potential determination. Moreover, the photocatalytic water splitting performance of Co-AISs with or without the modification of the multi-walled carbon nanotubes (MWCNTs) are investigated, and remarkable hydrogen production is achieved. This research will open a new gateway to synthesizing AgInS2-based materials and exploring their photocatalytic activities.

Natural Diatomite Supported Zirconium-Doped TiO2 with Tailoring Band Structure for Enhanced Visible-Light Photocatalytic Properties.

The development of economically applicable, highly efficient and low cost photocatalytic materials has always been a challenge. In this work, we report a zirconium doped TiO/diatomite (ZrTD) composite with enhanced visible light-induced photocatalytic activity. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, UV–VIS diffused reflectance spectroscopy, high-performance liquid chromatography-mass spectrometry, photoluminescence and X-ray photoelectron spectroscopy, respectively. The optimal doping ratio of zirconium into TiO was obtained at 3% (3%ZrTD composite), and the degradation rate constant of which tetracycline (TC) is up to around 8.65 times higher that of zirconium doped TiO. In addition, zirconium doping introduces the impurity levels of Zr 3d and oxygen vacancies into the lattice of TiO, resulting in broadening the light absorption range, reducing the band gap, and improving the separation efficiency of photogenerated electron-hole pairs, thus endowing with visible light photocatalytic properties. Moreover, both the photogenerated holes (h) and superoxide (•O) radicals are responsible for the degradation process of TC, and a possible degradation pathway and the corresponding intermediate products of TC by ZrTD composite are also proposed in detail.

Visible-light-driven 2D/2D Bismuth oxyhalides/covalent organic framework heterojunctions for synchronous photocatalytic U(VI) reduction and bisphenol A degradation

Bismuth oxyhalides (BiOX, X = Cl, Br, I) with two-dimensional (2D) layered structures have strong photocatalytic properties. 2D covalent organic frameworks (COFs) are metal-free photocatalysts with extended π-conjugated layer structure, high specific surface area and chemical stabilities, and have extraordinary application potential. Here, the novel double layer of BiOX@TpPa-1 composites were constructed to integrate the advantages of narrow bandgap and efficient separation of photogenerated carriers. After TpPa-1 modification, the bandgap of BiOX can be adjusted from 2 to 3 eV to 1.5–1.84 eV due to electronic rich π-conjugated system of TpPa-1, which remarkably increased the utilization of solar energy. The optimal doping ratio of BiOX@TpPa-1–5% manifested the highest catalytic activity for simultaneous U(VI) reduction (48.6%~81.2%) and bisphenol A (BPA) (43.4%~57.6%) degradation under visible light, which can be attributed to the existence of oxygen vacancies and the efficient production of electrons and •O2− radicals. After deducting the dark adsorption reaction, compared with the single BiOX (10%~30%), the removal efficiencies of BiOX@TpPa-1 (42.6%~53.6%) for photoreduction U(VI) were significantly improved, especially for BiOCl@TpPa-1. The enhanced photocatalytic performance of BiOX@TpPa-1 was systematically identified by photoelectrochemical characterizations, such as PL, Mott-Schottky plots, EIS, I-t. Furthermore, the efficiency of BiOX@TpPa-1 for the photocatalytic U(VI) reduction and BPA degradation remained relatively stable after recycling, exhibiting the good reusability and stability. Therefore, this study provided the construction of inorganic-organic composite photocatalysts with excellent performance and stability for the extensive application prospect in the field of environmental purification.

Steering Unit Cell Dipole and Internal Electric Field by Highly Dispersed Er atoms Embedded into NiO for Efficient CO2 Photoreduction

AbstractThe weak internal electric field over antiferromagnetic materials makes it difficult to facilitate charge migration to the surface, leading to low performance for CO2 photoreduction. The asymmetry and polarization refinement structure can induce an intensive internal electric field. Herein, n‐type NiO is synthesized with highly dispersed erbium atoms doping (Er/NiO1−x) via a molten salt method to accelerate charge separation and transfer. The doping of Er atoms can distort the unit cell of NiO to alter the symmetry and enhance the polarization and internal electric field, in favor of efficient separation of charges. In addition, the highly dispersed erbium‐doped n‐type NiO can largely boost the adsorption and activation of CO2, and weaken the energy barrier for CO2 photoreduction reaction. Benefiting from the unique features, an optimal doping ratio (≈2%) with erbium atoms achieves a remarkable elevation in carrier separation efficiency and excellent CO2 photoreduction performance with a CO yield of 368 µmol g−1 h−1 in the Ru(byp)32+/ethanolamine electron‐agent generating system, which is 26.3‐fold and 3.9‐fold relative to traditional NiO and n‐type NiO, respectively. The obtained Er/NiO1−x photocatalyst and the unit cell dipole governing the internal electric field opens a new window for CO2 photoreduction in antiferromagnetic materials.

Effects of carbon, graphite, and graphene as propellant dopants in a laser-electric hybrid acceleration system

With the combination of laser ablation and electromagnetic acceleration, the laser–electric hybrid thruster is now perceived as an advanced propulsion system to support the precise maneuvering of microsatellites. To improve the performance of a laser–electric hybrid acceleration thruster, we used carbon, graphite, and graphene as dopants to modify the polymeric propellant fed into it. The impulse bit, consumed mass, discharge success rate, specific impulse, momentum coupling coefficient, and efficiency were measured and analyzed. Results showed that these three dopants led to higher values of impulse bit, specific impulse, discharge success rate, efficiency, and momentum coupling coefficient. The samples doped with carbon and graphene yielded better performances than those doped with graphite. Furthermore, the propellant sample made of 5% graphene and 95% polytetrafluoroethylene yielded the highest impulse bit of 394.7 μN·s, largest specific impulse of 1012.05 s, highest momentum coupling coefficient of 16.21 N/MW, and maximal efficiency of 8.21%. Furthermore, we compared the performances of the doped samples at different filling ratios and different operations. It was found that 5% was the optimal doping ratio for the dopants of carbon and graphene, and a higher discharge width could effectively improve the performances of the carbon-doped and graphene-doped samples.

Se-doped cobalt oxide nanoparticle as highly-efficient electrocatalyst for oxygen evolution reaction

Electrolysis of water has been one of the most promising approaches for renewable energy resources while the efficient oxygen evolution reaction (OER) remains challenging. Herein, a series of different ratio of Se doped Co3O4 nanoparticles XSe-Co3O4 are prepared by hydrothermal method and applied as OER electrocatalysts. Se2− is doped into the Co3O4 crystal lattice by substituting of O2− and a large number of oxygen vacancies are generated, which provides more available activity sites for OER. Se doping increases the surface ratio of Co2+/Co3+ and accelerates the electron transport that favors OER activity promotion. The optimized doping ratio of 6%Se–Co3O4 presents low overpotential of 281 mV at 10 mA cm−2, as well as a low Tafel slope of 70 mV dec−1 in 1 M KOH solution, which has great advantages compared to the recently reported Co3O4-based OER electrocatalysts. This work provides new ideas for the development of efficient Co3O4-based OER electrocatalysts.

Powdered activated carbon doping improves the mechanical and adsorption properties of cementitious microfiltration membrane

Cementitious membrane (CM) is a promising microfiltration membrane with low cost for raw materials and low energy consumption of non-sintering fabrication process. A novel carbon-cementitious microfiltration membrane (CCM) was fabricated with powdered activated carbon (PAC) as an additive based on CM, to solve the low mechanical strength of CM during multiple practical uses. While maintaining adequate pure water flux and porosity, the mechanical strength of the membrane was greatly improved to ensure the stability of the membrane in the filtration process. The bending strength of the CCM was 2–3 times higher than that of CM. 10 wt% CCM has the smallest critical pore size and optimal permeability, which was chosen to be the optimal PAC doping ratio. The X-ray diffraction and FT-IR results indicated that the addition of PAC did not change the mineral composition of cement hydration products, and the appropriate amount of PAC acted as a nucleation site and accelerated hydration. The effect of size effect on bending strength was more obvious with the decrease of membrane thickness. In the membrane adsorption experiments of benzophenone-4, nitrobenzene and p-chloronitrobenzene, the CCM exhibited prominent adsorption properties than CM. These results broaden the application scope of microfiltration membranes in water treatment process.

Impeding the charge recombination through modifying the electron–phonon coupling in organic charge transfer complexes

The third component doping is considered as an effective method to improve the performance of organic photovoltaics and to understand the role of the third component on the charge dissociation in ternary complexes. In this work, through changing the doping ratio of the third component, the electron–phonon (e–p) coupling coefficient is tuned, where the e–p coupling dependence of charge recombination is studied in ternary charge transfer complexes. Modifying the e–p coupling by an optimized doping ratio of the third component will effectively suppress charge recombination in ternary charge transfer complexes. Furthermore, the e–p coupling coefficient is tightly dependent on the external light intensity and temperature. Overall, the insights gained from this study may be of assistance to provide further information for improvement in the organic photovoltaics.

Effect of incorporating two-dimensional transition metal Mo and photoelectric element Ga on micro-characteristic of chalcogenide-based ZnS/Se

There is a challenge to increase the application range of chalcogenide materials due to the fixed photoelectric properties and complex preparation process. To solves the problem, bulk ceramics with different doping ratios should be investigated. Here, the influence of the doping ratio of molybdenum MO and Ga oxide on the composition, structure, morphology and luminescence properties of bulk ceramics is studied, the optimal doping ratio in this range is determined by analysis of mass loss and volume shrinkage. The cubic crystal structure is confirmed by X-ray diffraction results. The results showed that molybdenum was successfully doped Mo into the matrix material is revealed by Raman spectroscopy. The X-ray fluorescence is used to study the composition ratio changes of bulk ceramics before and after sintering. The molecular structure model of Mo–ZnSe/ZnS with different concentration is constructed. The X-ray photoelectron spectroscopy shows the spin orbits of Zn 2p and S 2p, as well as the +3 valences in terms of Mo and Ga. The optical performance is enhanced the light-emitting band is enlarged to the near infrared region. All the work suggest that this new compound has an improved micro-structural, optical and electrical properties. This research can provide theoretical and experimental reference for the doping research of chalcogenide materials and new optoelectronic devices.

Reaction performance of CaCO3/CaO thermochemical energy storage with TiO2 dopant and experimental study in a fixed-bed reactor

The CaCO3/CaO reversible reaction pair is a promising thermochemical energy storage (TCES) technology for concentrating solar power (CSP) plants. However, the reaction performance and cyclic stability of this reaction pair is compromised because of sintering. In this study, TiO2-doped in CaCO3/CaO TCES system are systematically investigated by synchronous thermal analyzer (STA). The reaction kinetics of decarbonation process with and without TiO2 doping are compared in N2 and CO2 atmospheres. Furthermore, the performance of CaCO3/CaO TCES system is analyzed in a fixed-bed reactor for future application. It is found that doping TiO2 can improve the anti-sintering ability and cyclic stability of CaCO3, and the optimal doping ratio is 2.5 mol %, whose energy storage density is 1256.68 kJ/kgsample at first and improved by 2.26 times after 30 cycles. Moreover, doping TiO2 decreases the activation energy and initial decarbonation temperature in CO2 atmospheres. In exothermic experiments of fixed-bed reactor, the maximum exothermic temperature difference is 309.83 °C at 550 °C, and the highest absolute temperature reaches 848.7 °C at 750 °C. TiO2 dopant promotes the decarbonation at lower temperature, and obtains a higher overall conversion (0.506) at 850 °C. Overall, CaCO3 with TiO2 dopant is of great significance for future industrial and commercial applications.

Gold nanorods doping induced performance improvement of room temperature OTFT NO2 sensors

Solution-processed organic thin-film transistors (OTFTs) are regarded as the promising candidates for low-cost gas sensors due to their advantages of high throughput, large-area and sensitive to various gas analytes. Microstructure control of organic active layers in OTFTs is an effective route to improve the sensing performance. In this work, we report a simple method to modify the morphology of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) thin films via doping gold nanorods (Au NRs) for enhancing the performance of the corresponding OTFT sensors for nitrogen dioxide (NO2) detection. With the optimized doping ratio of Au nanorods, the TIPS-pentacene OTFT snesors not only exhibit a 3-fold increase in mobility, but also obtain a high sensitivity of 70% to 18 ppm NO2 with a detection limit of 270 ppb. The microstructures and morphologies of the modified TIPS-pentacene thin film characterized by atomic force microscopy and field scanning electron microscope. The experimental results indicate that the proper addition of Au NRs could effectively regulate the grain size of TIPS-pentacene, and therein control the density of grain boundaries during the crystallization, which is essential for the high-performance gas sensors.

Preparation and up-conversion luminescence characteristics studies of K3YF6: Ho3+, Yb3+ with cryolite structure

Cryolite was considered to be an ideal up-conversion host material due to its low phonon energy, which can effectively suppress the radiation-free transition process of excited state energy levels. In the present paper, a novel up-conversion material K3YF6:Ho3+, Yb3+ with cryolite structure was prepared successfully using a high-temperature solid state method. The up-conversion luminescence properties of K3YF6 doped with different Ho3+/Yb3+ doping ratio were investigated and the optimal doping ratio were confirmed in this system. Under 980 nm excitation, Ho3+/Yb3+ co-doped K3YF6 revealed a strong green emission at the 541 nm, 549 nm and a weak red emission peaking at 666 nm, corresponding to the 5F4, 5S2→5I8 and 5F5→5I8 transitions of Ho3+, respectively. All the red and green up-conversion emission of K3YF6:Ho3+, Yb3+ belong to two-photon process and energy transfer from Yb3+ to Ho3+ simultaneously. Additionally, to understand the energy transfer and electronic transition process of the red and green light emitted, the possible luminescence mechanism were also analyzed in this paper. All the results indicate that Ho3+/Yb3+ co-doped K3YF6 have potential application value in green up-conversion luminescent materials.

First demonstration of lithium, cobalt and magnesium introduced nickel oxide hole transporters for inverted methylammonium lead triiodide based perovskite solar cells

Nickel oxide as a popular hole transport material was frequently investigated through, Li, Co, Li-Co and Li-Mg co-doping strategies in the literature. Here, we report a new route based on the synergetic effect of Li-Co-Mg doping for nickel oxide using sol–gel method. For an optimized doping ratio, we observed a clear improvement in the photovoltaic performance of methylammonium lead triiodide (CH3NH3PbI3) based inverted perovskite solar cells that were fabricated in ambient air, under high humidity (>50%). Li-Co-Mg doping increased the work function, hole concentration, hole mobility, and electrical conductivity of the NiOx hole transport layers (HTLs). The addition of Co resulted in an undesired drop in the optical transmittance while increasing the surface roughness of the NiOx. It was witnessed that Mg addition healed both the transmittance and interface between HTL and perovskite. Even for the precursor solution, we noticed that by the addition of Mg into the Li and Co-doped NiOx precursor, the solution became more transparent and stable. Photovoltaic measurements revealed that the short-circuit current density increased from 17.3 to 23.9 mA cm−2, the open-circuit voltage was boosted from 0.932 to 1.06 V, and the fill factor was improved from 0.46 to 0.52. Consequently, power conversion efficiencies were found to be increased by up to 13.22% from 7.47% by the Li-Co-Mg doping. We believe our results demonstrate that Li, Co and Mg doping might be a promising way for adapting nickel oxide hole transport layers for CH3NH3PbI3 based perovskite solar cells.

Efficient green indium phosphide quantum dots with tris(dimethylamino)-phosphine phosphorus precursor for electroluminescent devices

In this study, green indium phosphide (InP) quantum dots (QDs) were synthesized using a tris(dimethylamino)phosphine ((DMA)3P) phosphorus source and applied to electroluminescent quantum light-emitting diodes (QLEDs). The (DMA)3P precursor is safer and more cost-effective than the conventional tris(trimethylsilyl)phosphine. The emission peak of the InP QDs was shifted to the green region from the red by replacing the conventional zinc precursor ZnCl2 with ZnI2. The surface reaction rate was limited using ZnI2 in the core formation step, yielding small-sized QDs to achieve green emission. In addition, with the optimal ZnSeS intermediate shell and outer shell, the maximum quantum yield of 67.5% with a narrow full width at half maximum of 46 nm was achieved for the (DMA)3P-based green-emitting InP@ZnSeS/ZnS QDs. QLEDs were demonstrated with the (DMA)3P-based green InP QDs, and their efficiency was maximized by optimizing the Mg doping ratios in the electron transport layer (ETL) of ZnMgO. The maximum external quantum efficiency of 1.68% and current efficiency of 4.79 cd/A were achieved with an optimal doping ratio of 12.5% ZnMgO for the (DMA)3P-based green InP QLEDs. This study demonstrates that safer (DMA)3P phosphide source-based green InP QDs are effective in achieving low-cost InP QLEDs.

CoS2/MoS2 decorated with nitrogen doped reduced graphene oxide and multiwalled carbon nanotube 3D hybrid as efficient electrocatalyst for hydrogen evolution reaction

Designing an efficient and stable electrocatalyst made of earth abundant elements to take over expensive noble metal based for Hydrogen Evolution Reaction (HER) have been focused. Cobalt disulfide-molybdenum disulfide nanocomposite supported by nitrogen doped reduced graphene oxide and multiwalled carbon nanotubes (CoS2/MoS2@NrGO-MWCNT) is reported as an efficient electrocatalyst for HER. CoS2/MoS2@N-rGO-MWCNT and ternary hybrids composed of CoS2, MoS2 and N-rGO/MWCNT have been investigated. The catalysts were prepared by facile hydrothermal method, and the optimal doping ratio referred to date cobalt to molybdenum as 2:1 was chosen. It is found that co-existence of CoS2, MoS2 brings abundant active sites and incorporation of MWCNT offered stability. Good dispersion of CoS2 nanoparticles on graphene and MoS2 sheets is observed. Additionally nitrogen doping on rGO sheets has been carried out to boost up the electronegativity of the catalyst as a support to enhance the catalytic activity of CoS2/MoS2 for refine structure and better electrical conductance. Precisely, CoS2/MoS2@N-rGO-MWCNT exhibited smaller tafel slope 73 mV dec−1 at overpotential 281 mV for current density 10 mA cm−2 and the substantial stability of 14 h is recorded in 0.5 M H2SO4 medium, results suggest that catalyst is viable alternate for HER.

Fabrication of ternary AgBr/BiPO4/g-C3N4 heterostructure with dual Z-scheme and its visible light photocatalytic activity for Reactive Blue 19

A plasmonic photocatalyst of AgBr/BiPO4/g-C3N4 was prepared. X-ray powder diffraction, Scanning electron microscope, Transmission electron microscopy, Fourier infrared spectroscopy, Ultraviolet Visible diffuse reflectance spectroscopy and photoluminescence emission spectra have been employed to determine the structure, morphology and optical property of the as-prepared AgBr/BiPO4/g-C3N4 composite and analysis the reasons for improving photocatalytic efficiency. The optimal doping ratio of AgBr was 10 wt% by degrading 20 mg/L of Reactive Blue 19 (RB19) under visible light (λ > 420 nm), and 10 wt%AgBr/BiPO4/g-C3N4 degraded 20 mg/L of RB19 to 2.59% at 40 min, which is ascribed to synergistic effects at the interface of AgBr, BiPO4 and g-C3N4. The effect of catalyst dosage, initial concentration and initial pH of RB19 solution on photocatalytic efficiency was investigated. Four cycles of experiments were conducted. Finally, through the trapping experiment, we found that the main active factor for degrading RB19 in the photocatalytic process is O2-. The possible photocatalytic mechanism of AgBr/BiPO4/g-C3N4 was discussed in connection with the synergistic effect of Ag and active substances at the AgBr/BiPO4/g-C3N4 interface.

Sc-doped NiO nanoflowers sensor with rich oxygen vacancy defects for enhancing VOCs sensing performances

Identifying the defect type which closely correlates with gas/metal oxide semiconductor (MOS) interfacial charge exchange is of utmost importance for rationally designing high performance MOS gas sensors, which are essential for the emerging sensing electronics for assessing the personal health and environment pollution. Herein, we report the sensing performance of p-type NiO toward volatile organic compounds (VOCs) molecules could be drastically improved by Sc dopant. At an optimal doping ratio of 7.4 at.%, the sensor response to 100 ppm acetone was boosted from 8.2 (pure NiO) to 109.4, with a low detection limit of 10 ppb. Comprehensive defect characterizations indicate surface unsaturated oxygen vacancy (VO) defects act as active sites that facilitate the interfacial charge exchange at elevated temperatures. Our work highlights that abundant VO defects induced by aliovalent Sc dopant play an important role in boosting the sensitivity of p-type NiO toward VOCs, and provide valuable guidance in designing high performance p-type MOS sensors.