Matching Band Research Articles

Water-stable perovskite CsPb2Br5/CdSe quantum dot-based photoelectrochemical sensors for the sensitive determination of dopamine.

A heterojunction of CdSe quantum dots in situ grown on the perovskite CsPb2Br5 (CsPb2Br5/CdSe) for water-stable photoelectrochemical (PEC) sensing was simply synthesized using the hot-injection method. Due to the inherent built-in electric field and the matching band structure between CsPb2Br5 and CdSe, the CsPb2Br5/CdSe p-n heterojunction demonstrates enhanced photoelectrochemical properties. Accelerated interfacial charge transfer and increased electron-hole pair separation enable hydrolysis-resistant CsPb2Br5/CdSe sensors to exhibit heightened sensitivity with an ultra-low detection limit (0.0124 μM) and a wide linear range (0.4-303.9 μM) in subsequent dopamine detection. Moreover, the CsPb2Br5/CdSe sensors show excellent anti-interference ability, as well as remarkable stability and reproducibility in water solvent. It is noteworthy that this work is conducted in an aqueous environment, which provides an inspiring and convenient way for photoelectric and photoelectrocatalysis applications based on water-resistant perovskites.

Antimony incorporated flexible Cu2ZnSn(S,Se)4 solar cell for enhanced mechanical endurance and efficiency

Balancing the efficiency and mechanical endurance of flexible Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells is challenging its potential applications of the day. Here, a straightforward strategy is developed to prepare flexible solar cells with the coexistence of photovoltaic performance and flexibility by introducing a novel SbCl3 in precursor solution. Sb-doped CZTSSe thin film with progressive grain growth from nanoscale to microscale and strengthened toughness with porosity from 8.13 % to 2.44 % is obtained. By exploiting the benefits of upgrading the band matching and tailoring the residual stress, SbCl3 solution with a concentration of 0.30 mol/L achieves the optimum heterojunction characteristic and mechanical performance. The final structured device with improved efficiency from 3.27 % to 4.98 % and indomitable mechanical endurance is attained, which can reserve 93 % of its original efficiency after bending 200 times. The present work indubitably paves a convenient way toward efficient and flexible photovoltaic devices.

Quantum optical tomography based on time-resolved and mode-selective single-photon detection by femtosecond up-conversion

We developed an optical time-of-flight measurement system using a time-resolved and mode-selective up-conversion single-photon detector for acquiring tomographic images of a mouse brain. The probe and pump pulses were spectrally carved from a 100-femtosecond mode-locked fiber laser at 1556 nm using 4f systems, so that their center wavelengths were situated at either side of the phase matching band separated by 30 nm. We demonstrated a sensitivity of 111 dB which is comparable to that of shot-noise-limited optical coherence tomography and an axial resolution of 57 μm (a refractive index of 1.37) with 380 femtosecond probe and pump pulses whose average powers were 1.5 mW and 30 μW, respectively. The proposed technique will open a new way of non-contact and non-invasive three-dimensional structural imaging of biological specimens with ultraweak optical irradiation.

Flexible Approximation Functions: Resonant Loads

Introduction. Patch antennas have found wide application in UAVs due to their numerous useful properties. However, since such an antenna system is essentially a resonator, the problem of its matching remains unresolved. The existing publications mostly deal with specific cases and report the typical values of the matching band of 5–7 %, which cannot be considered sufficient when there is a need to use the signal spectrum of up to hundreds of MHz. Therefore, research aimed at using more efficient methods of broadband matching could be of interest for engineers. Aim. To develop a broadband matching technique based on the generalized Darlington synthesis method using flexible approximating functions (AF) for load models with resonant properties. Materials and methods. The capabilities of the generalized Darlington synthesis method are extended AFs with increased variation properties. Flexible control of AF weight coefficients makes it possible to realize both smooth and wave frequency characteristics. The method is analytical and does not use iterative procedures. The mathematical apparatus of the method is based on an analysis of deductions in the zeros of the load resistance transfer function. Results. Flexible approximating functions were established to be effective for synthesis of matching circuits with resonant properties. Solutions for matching the loads with multiple transfer zeros both at the origin and in infinity were obtained. The opportunity of creating patch antennas with a matching layer up to 40 % and more was demonstrated. Conclusion. The results obtained for the SWR of patch antennas show that the potential estimates of matching limits are available only for analytical methods.

MOF-Derived In2O3 Microrod-Decorated MgIn2S4 Nanosheets: Z-Scheme Heterojunction for Efficient Photocatalytic Degradation of Tetracycline.

The construction of Z-scheme heterostructures using matching band semiconductors is an effective strategy for producing highly efficient photocatalysts. In this study, MgIn2S4(MIS) was grown in situ on In2O3 microrods created with an In-based MOF material (In-MIL-68) as a template to successfully establish a unique MIS-In2O3 heterojunction with a well-matched Z-scheme interface charge transfer channel. Tetracycline (TC) as a typical antibiotic was chosen as the target pollutant to evaluate the photocatalytic activity. After 120 min of visible light irradiation, the MIS-In2O3-(10:1) material had the greatest photocatalytic degradation activity of tetracycline with 96.55%, which was 2.39 and 4.26 times that of MIS and In2O3, respectively. The improved photocatalytic activity is attributed to the in situ growth of MIS on In2O3, forming a Z-scheme heterojunction at the interface, which not only increases the specific surface area, exposes the abundant active site, and improves light utilization but also facilitates the migration and separation of photogenic carriers. The photocatalytic degradation products of TC were detected by liquid chromatography-mass spectrometry (LC-MS), and a preliminary degradation pathway was proposed. Radical capture experiments and ESR analysis confirmed that the main active species were holes (h+), superoxide radicals (•O2-), and superoxide and hydroxyl radicals (•OH). Finally, combined with band position analysis, this study proposes a direct Z-scheme heterojunction mechanism to improve the photocatalytic degradation of tetracycline in MIS under visible light.

Tuning band structures at metal sulfides/Zr-MOF heterojunctions: modulate optical-electronic properties to boost photocatalytic detoxification of Cr(VI) and degradation of reactive dyes

Assembly of advanced MOFs based heterojunctions is an effective avenue to facilitate light utility and photogenerated electron-hole separation for photochemical detoxification of Cr(VI) and degradation of reactive dyes. Systematically polishing the band states of photocatalysts is the crucial point but still requires further study. Herein, a band structure tuning strategy was designed by depositing carefully selected metal sulfides on a 2D Zr-MOF to assemble six metal sulfides/Zr-MOF heterojunctions. Fortunately, In2S3/Zr-MOF presents prominent optical-electronic properties and photocatalytic performances since the highly matched band structure. And its UV–Visible light utility, carriers migration rate, electron-hole separation efficiency and recombination inhibition ability have been greatly optimized. Ingeniously, In2S3/Zr-MOF (M5) exhibits best photochemical purification abilities towards ultra-stubborn reactive dyes RR11, RB21 and highly toxic Cr(VI) ions, under 500 W xenon lamp, with degradation/reduction efficiencies of 91.8, 93.3 % and 97.9 % within 5, 13 h and 70 min, respectively. Compared with pure In2S3 and Zr-MOF, the photocatalytic degradation kinetics towards RR11 have been increased 27.18 and 38.50 times, respectively, providing the recyclability of more than 4 times. Mechanism studies confirm that ·O2− species play dominant roles in removal of reactive dyes, and the powerful electrons transfer from the conduction band (CB) of In2S3 to Zr-MOF's relatively positive CB further reinforce their ability to combine with dissolved O2 in water to provide more ·O2−. While the cooperation of electrons in CB of Zr-MOF with O2/·O2− has been suggested as the mechanism for photocatalytic detoxification of Cr(VI) to Cr(III). This study provides a feasible strategy for boosting the photochemical purification capacities of Zr-MOFs based heterojunction platforms.

Integration of Sentinel-2A Imagery and Laboratory Measurements for Estuarine Pb and TSS Concentration Monitoring in Suwung, Denpasar City, Indonesia

Research has been carried out on integrating the results of Sentinel-2A and laboratory image data measurements in the form of a mathematical model that can be used to estimate the concentration and spatial distribution of Pb and Total Suspended Solid (TSS) of the Suwung estuary, Denpasar city, Bali, Indonesia. Integration is carried out using the regression method and correlation of the pixel value measurement results of the Sentinel-2A and laboratory images. Pixel values in Sentinel-2A image data which represent TSS concentrations are obtained by applying the TSS algorithm and Pb pixel values through Sentinel-2A band matching. The number of samples tested was 30 which were taken and measured at predetermined coordinate points. There are differences in the results of concentration measurements, both Pb and TSS obtained from laboratory measurements with Sentinel-2A pixel values. The integration results obtained in the form of a mathematical model in this research are for Pb, it is p=33.757q – 1.1345 and for TSS it is y=1.0213x – 0.2921. The variables p and y are the results of laboratory measurements, while the variables q and x are the results of measuring the Sentinel-2A pixel values. The spatial distribution of Pb detected was mostly on the west side and a small part on the east and north. For TSS, most of it is upstream in the north, while a small part is in the south and east.

Embedding CsPbBr3 Quantum Dots into an In2O3 Nanotube for Selective Photocatalytic CO2 Reduction to Hydrocarbon Fuels.

Halide perovskite quantum dots (QDs) are one of the most prospective candidates for photocatalytic CO2 reduction, but their photocatalytic performances are far from satisfactory due to structural instability and severe charge recombination. In this study, we demonstrated a CsPbBr3 QDs/In2O3 hierarchical nanotube (CPB/IO) for efficient CO2 conversion, in which CsPbBr3 QDs were well-dispersed on the In-MOF-derived In2O3 nanotube by a facile self-assembly process. The optimized CPB/IO catalyst displayed an enhanced photocatalytic CO2 performance with a (CO + CH4) generation rate of 16.37 μmol·g-1·h-1 upon simulated solar illumination without a photosensitizer and sacrificial agent, which is 3.59 times stronger than that of pristine CsPbBr3 QDs (4.56 μmol·g-1·h-1). Besides, the modified CsPbBr3 QD catalyst exhibited an obvious increase of CH4 selectivity and excellent stability after four cycles. The unique zero-dimensional (0D)/one-dimensional (1D) heterostructure and matching band potentials between CsPbBr3 and In2O3 supply an intimate interfacial contact, numerous active sites, and effective charge transfer for CO2 photoreduction. This work can inspire the formation of novel halide-perovskite-involving photocatalysts for solar fuel formation.

Design of a Wideband, High Steering Angle and Low Side-Lobes Levels Matrix Antenna

This paper presents the use of pixel-type radiating elements in the context of broadband beam steering. The elements are composed of a resonant cavity topped by a frequency selective surface, fed via a patch antenna and filled with dielectric substrates. This pixel antenna has a wide -10 dB matching band from 1.22 to 1.61 GHz, which corresponds to a 27% fractional bandwidth. It has an angular aperture greater than 124° and a realized gain between 3.3 and 3.8 dBi over the whole matching band. An array composed of 5 elements has been simulated and allows a steering on a range of ±60° in the E plane while keeping the gain variation below 3 dB. A prototype has been manufactured and presents a steering capacity between -56 and 53° on the whole band with side-lobes levels lower than -8.1 dB whatever the angle.

Exploring locality sensitive hashing as a blocking method for large-scale administrative datasets

ObjectivesLinking large-scale datasets is challenging due to the computational power required. This research explores using Locality-Sensitive-Hashing (LSH) as a blocking method to reduce the computational complexity when linking large administrative datasets. LSH hashes similar data into ‘buckets’, thus reducing the search space and processing power required to find links.
 MethodsA gold-standard linked dataset was used during method development. Test datasets were made using samples of gold-standard matches and non-matches, then blocked using LSH.
 Various LSH parameters including shingle length, signature length, band size and number of matching bands were tested. Precision and recall were used to find optimal parameters for identifying good candidate pairs, with 100% recall and >20% precision being desirable.
 Alternative formats for date of birth, postcode and gender variables were tested, with additional characters used to simulate agreement weighting.
 ResultsResults as of spring 2023 are promising, with the caveat that currently only small datasets have been tested. The LSH method with optimal parameters creates ~9,000 candidate pairs whilst maintaining recall of 100% (i.e., all true matches are included in the candidate pairs) and precision of 27.6%. In contrast, our traditional deterministic blocking method using the same variables creates ~70,000 candidate pairs, and a cartesian product creates over 23.4 million candidate pairs. We have therefore shown that LSH can be used to create a significant reduction in the search-space size.
 Furthermore, the method easily handles alternative names, postcodes, etc. that may be present in longitudinal data or composite datasets, with no need to account for different possible combinations of variables.
 ConclusionCurrent research has shown that LSH can be used to drastically reduce the search space when blocking for data linkage. Using variable formatting to prioritise agreement for specific sections e.g., of postcode, has overcome a potential downside of LSH. Further research on variable formatting, parameter optimisation and testing of the method at scale is ongoing.

Double shelled titanium dioxide@mesoporous organosilica nanotube as an amphiphilic photoactive nanoreactor for efficient photocatalytic oxidation of styrene

In this work, we have proposed a strategy to fabricate double-shell nanotubes as amphiphilic photoactive nanoreactors (HTTBPC) through the ordered hybridization of mesoporous organosilicon (PMO) and titanium dioxide (TiO2) nanotubes. Unlike the previous rough composite, the heterogeneous structure established between cobalt-porphyrin functionalized PMO and conventional TiO2 has a staggered matching band gap, which makes it have excellent light harvesting and high carrier separation ability. This is still unexplored. Interestingly, the prepared photocatalysts exhibited superior activity (99%) and benzaldehyde selectivity (94%) in the oxidation of styrene in water at room temperature, which was 3.8 and 2.8 times higher than that of TiO2 nanotubes and PMO functionalized with cobalt porphyrin, respectively. It was demonstrated that the strong interaction between cobalt porphyrin PMO and TiO2 improved the separation of photogenerated carriers and the amphiphilic properties of mesoporous organosilica boosted the adsorption of substrate molecules in water, contributing to the significantly enhanced photocatalytic activity. This work provides a design of high-performance photocatalysts for alkene oxidation under green conditions.

Fabrication of Bi2MoO6/g-C3N4 visible-light driven photocatalyst for enhanced tetracycline degradation

Bi2MoO6/g-C3N4 photocatalysts with different mass ratios were prepared by heat treatment and simple hydrothermal methods. The composition, microstructure, morphology and optical properties of the photocatalysts were characterized by XRD, SEM/TEM, UV–vis-DRS, FTIR, XPS, EIS and PL. Tetracycline was used as the target organic contaminant to evaluate the photocatalytic performance of Bi2MoO6/g-C3N4. The composite photocatalyst with the mass ratio of g-C3N4 8 % exhibited the highest of 97.5 % tetracycline degradation after 120 min under visible light, the degradation rate is 6.5 and 3.3 times higher than that of pure Bi2MoO6 and g-C3N4, respectively. The trapping experiment results showed that holes, superoxide and hydroxyl radicals were all involved in the photocatalytic reaction. The enhanced photocatalytic ability was attributed to the matched band structure and tightly connected heterojunction between Bi2MoO6 and g-C3N4, which effectively prevents the recombination of photogenerated carriers.

Solution‐Processed PEDOT:PSS/p‐Si/ZnO Heterojunction Solar Cells

With the introduction of the concept of dopant‐free carrier‐selective contact for c‐Si photovoltaics, Si‐based heterojunction solar cells can greatly reduce production costs by optimizing the manufacturing process while maintaining high power conversion efficiency. Compared with processes that rely on complex vacuum equipment, low‐temperature solution processing has many advantages over conventional silicon solar cells. However, research on low‐cost and high‐efficiency solar cells based on p‐type crystalline silicon is relatively rare. From the point of view regards energy band matching, the inorganic metal oxide semiconductor material ZnO is well suited for low‐cost solution method studies due to its easy preparation, very high transmittance in the visible spectrum, low cost, and suitable energy levels matching p‐Si. Herein, ZnO is spin coated on the back of p‐Si to form a heterojunction, together with spin coating of PEDOT:PSS on the front side as the hole transport layer and passivation layer, a PEDOT:PSS/p‐Si/ZnO‐structured p‐Si‐based backcontact hybrid solar cell is successfully fabricated at low temperature (≤135 °C) via solution process with a PCE of 9.77% (Voc = 0.56 V, Jsc = 25.99 mA cm−2, fill factor = 67.10%). This work provides a promising approach for fabricating high‐performance and low‐cost silicon‐based heterojunction solar cells.

Efficient Visible-Light Photocatalytic Hydrogen Evolution over the In2O3@Ni2P Heterojunction of an In-Based Metal-Organic Framework.

Although the engineering of visible-light-driven photocatalysts with appropriate bandgap structures is beneficial for generating hydrogen (H2), the construction of heterojunctions and energy band matching are extremely challenging. In this study, In2O3@Ni2P (IO@NP) heterojunctions are attained by annealing MIL-68(In) and combining the resulting material with NP via a simple hydrothermal method. Visible-light photocatalysis experiments validate that the optimized IO@NP heterojunction exhibits a dramatically improved H2 release rate of 2485.5 μmol g-1 h-1 of 92.4 times higher than that of IO. Optical characterization reveals that the doping of IO with an NP component promotes the rapid separation of photo-induced carriers and enables the capture of visible light. Moreover, the interfacial effects of the IO@NP heterojunction and synergistic interaction between IO and NP that arises through their close contact mean that plentiful active centers are available to reactants. Notably, eosin Y (EY) acts as a sacrificial photosensitizer and has a significant effect on the rate of H2 generation under visible light irradiation, which is an aspect that needs further improvement. Overall, this study describes a feasible approach for synthesizing promising IO-based heterojunctions for use in practical photocatalysis.

Regulation of the band structure and water solubility of perylene imide derivatives based on bay-substitution to accelerate the transport of photogenerated carriers with TiO2

Improving the efficiency of photogenerated charge separation and transport is the primary goal of designing and constructing efficient composite photocatalysts. The matching of energy bands and the formation of chemical bond between the two components are very conducive to the separation and transmission of photogenerated charges. Herein, three perylene diimide derivatives (PDIs) are synthesized by introducing sulfonic acid group (PDI-SA) and benzenesulfonic acid (PDI-BSA) respectively into the amide bond and further chlorine bay-substituting (Cl-PDI-BSA). The good water solubility of Cl-PDI-BSA ensures its forms a stable chemical bond with TiO2 through the sulfonic acid group in the single molecular state, coupled with the matching of energy band structure, TiO2@Cl-PDI-BSA exhibited excellent performance upon visible light photocatalytic degradation to phenol and trenbolone acetate (TBA). It can remove 100% of phenol in 15 min and 100% trenbolone acetate (TBA) in 30 min, which is 14.3 times that of TiO2. Combining to DFT calculation, Kelvin probe force microscope and EPR analysis prove that bay chlorine substitution has a greater impact on the energy band structure and electron cloud distribution of PDIs than N-sulfonation, thereby seriously affecting the transport of photogenerated carriers with TiO2.

An S‐band wide beam miniaturized omnidirectional circularly polarized antenna

AbstractA wide beam miniaturized broadband omnidirectional circularly polarized antenna operating at S‐band is proposed. It is composed of a hub‐shaped circular horizontally polarized radiator, a vertically polarized radiator consisting of a monopole and eight shorting‐circuited pins, and a coupling feed device. The measured results indicate that the impedance matching band of |S11| < −10 dB is from 2.15 to 2.75 GHz (24.4%), and the band of the axial ratio <3 dB is from 2.2 to 2.7 GHz (20.4%). The gain of the antenna is about 1 dB, and the noncircularity in the azimuth plane is <1.2 dB. In addition, the antenna has the characteristics of wide axis ratio beam in the pitch plane with sizes of 0.68 λ0 × 0.68 λ0 × 0.14 λ0. The antenna is very suitable for satellite receiving system and short‐range wireless communication system.

Optimization of Electron Transport Layer‐Free Cs2TiBr6/MASnBr3 Laminated Structure Perovskite Solar Cells by SCAPS‐1D Simulation

Cs2TiBr6 materials have promising applications in organic–inorganic halide perovskite solar cells (PSCs), but their power conversion efficiency (PCE) is low. Herein, based on the matching band structure of MASnBr3 and Cs2TiBr6, a no‐electron transport layer (ETL)‐structured laminated PSC is constructed for numerical simulation using SCAPS‐1D. The results have shown that the ETL‐free structure reduces the potential barrier between the interfaces and improves the performance of the device. MASnBr3 is used to replace the traditional hole transport layer to form a laminated structure, which is more conducive to the built‐in electric field of the device. Through exploring the internal influencing factors and applicable environment, it is found that the device can maintain a good operating level between 230 and 430 K. Finally, the best PCE of 19.63% is achieved in the proposed device structure (FTO/Cs2TiBr6/MASnBr3/Au). This work provides a new approach to achieving lead‐free and efficient laminated PSCs in a wide temperature range of usage environments from −43 to 157 °C.

Low-Profile Lightweight Slot Array With Solar Cells for 5.8 GHz Band

A 4×4 slot array antenna with solar cells is presented for the 5.8 GHz band with a light weight and low profile of 0.039λ (λ is 5.8 GHz wavelength in the air). Coplanar waveguide excitation and foam substrate are adopted for a compact and lightweight structure. The measured impedance matching band is from 5.3 GHz to 6 GHz. The gain range is from 13.7 dBi to 16.3 dBi within the pass band. A tested peak gain of 14.8 dBi is achieved for the target band from 5.725 GHz to 5.85 GHz with unidirectional pattern. The solar cells can cover 72.5% of the total area with an enhanced capacity for photovoltaic power generation.

Efficient photocatalytic H2 production of g-C3N4 using nickel (II) functional complex as promoter

With the increasingly prominent energy and environmental problems, the construction of sustainable development, green environmental protection and new efficient energy system has become the focus of the world's attention. Photocatalytic hydrogen production technology is an important way to solve energy and environmental problems. The key to realizing the visible light catalytic water hydrogen production technology effectively lies in the selection of photocatalytic materials, graphite phase carbon nitride (g-C3N4) is an important photocatalyst. However, the photocatalytic performance of g-C3N4 is severely limited by the high recombination rate of photogenerated electron-hole pairs. Functional complex has a matching band gap with carbon nitride to form heterojunction structure, which can effectively reduce the photogenic carrier recombination and improve the catalytic hydrogen production performance. For this reason, the functional complex [Ni2(Medpq)2(BPDA)·2H2O] (BPDA = 4,4′-Biphthalic Anhydride, Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]quinoxaline) was synthesized by a hydrothermal process. The matching band gap between [Ni2(Medpq)2(BPDA)·2H2O] and g-C3N4 forms heterojunction structure, which effectively solve the defect of low utilization rate of light energy and improve the catalytic hydrogen production performance of g-C3N4. The experiment proved that complex/g-C3N4 photocatalytic rates of hydrogen production 2054.13 μmol·h−1·g−1, about 5.04 times that of pure g-C3N4 (407.56 μmol·h−1·g−1), thus high-performance of the hydrogen production from water decomposition was realized.

Extraordinary upconversion enhancement in mono-dispersed plasmonic resonant nanocavity coupling with lanthanide doped upconversion nanoparticles

In this work, we reported a monodispersed MDM (metal–dielectric-metal) type upconversion composite material with ultrahigh emission enhancement for the first time. Different from the planar configuration of traditional MDM systems, the proposed materials here consisting of silver nanoparticles as the metallic core, upconversion nanoparticles(UCNPs) as the intermediate dielectric layer, and silver layer as the metallic shell. The structural characteristics were investigated to explore the spectral band match between the plasmonics and UCNPs. The sandwich structure can create high density hot carriers at the nearfield region around the UCNPs, leading to the remarkable excitation enhancement. According to the proper structure design, the upconversion intensity can be enhanced by over five orders of magnitude. The outer metallic layer thickness, the diameter of attached UCNPs and the ambient refractive index were found responsible for the intensity enhancement. Such upconversion materials combined the merit of monodispersity and the high emission efficiency, which can improve their performance in bioimaging and photovoltaic device.