Faster Rate Research Articles

High-performing organic/quantum dot hybrid upconversion device based on a single-component near-infrared-sensitive layer

A donor/acceptor (D/A) heterojunction with an interfacial energetic offset is demonstrated to enable efficient exciton dissociation in organic photodetectors and upconversion devices (UCDs). Unfortunately, this approach usually encounters complicated optimization procedures and interfacial instability. Herein, we present an alternative strategy for achieving high-performing UCDs by utilizing an organic single-component near-infrared (NIR)-sensitive layer instead of a D/A heterojunction. The showcased UCD is constructed by vertically stacking an organic single-component Y6 NIR-detection unit and a quantum dot light-emitting unit. Due to the high dielectric constant and low exciton binding energy of the non-fullerene acceptor Y6, free carriers are directly and spontaneously generated upon NIR light excitation. As a result, the single-component UCD achieves a low light detection capability of 2.5 μW/cm2, a fast refresh rate of >3.8 × 104, and a high resolution exceeding 1100 dpi, providing a stable optical response to high-frequency NIR signals and high-quality NIR imaging.

Enhancing electrochemical carbon dioxide capture with supercapacitors

Supercapacitors are emerging as energy-efficient and robust devices for electrochemical CO2 capture. However, the impacts of electrode structure and charging protocols on CO2 capture performance remain unclear. Therefore, this study develops structure-property-performance correlations for supercapacitor electrodes at different charging conditions. We find that electrodes with large surface areas and low oxygen functionalization generally perform best, while a combination of micro- and mesopores is important to achieve fast CO2 capture rates. With these structural features and tunable charging protocols, YP80F activated carbon electrodes show the best CO2 capture performance with a capture rate of 350 mmolCO2 kg–1 h–1 and a low electrical energy consumption of 18 kJ molCO2–1 at 300 mA g–1 under CO2, together with a long lifetime over 12000 cycles at 150 mA g–1 under CO2 and excellent CO2 selectivity over N2 and O2. Operated in a “positive charging mode”, the system achieves excellent electrochemical reversibility with Coulombic efficiencies over 99.8% in the presence of approximately 15% O2, alongside stable cycling performance over 1000 cycles. This study paves the way for improved supercapacitor electrodes and charging protocols for electrochemical CO2 capture.

An effective strategy to construct pH-responsive microemulsion for cobalt recovery and its responsive mechanisms

Microemulsions for heavy metal separation show advantages of fast separation rate, high separation efficiency and extraction capacity. However, it remains challenging in destabilizing microemulsions for back-extraction due to their thermodynamic stability. This study describes an effective strategy to construct pH-responsive microemulsion by adding N,N-dimethylethanolamine (DMEA) during back-extraction to avoid the negative impact of responsive materials on the extraction, meanwhile the back-extraction can be realized through a mild pH stimulus compared to traditional strong acid demulsifier. Cetyltrimethylammonium bromide (CTAB)-stabilized microemulsion was formulated and optimized for the selective Co(II) extraction reaching 95.4 %, while extraction efficiency of Ni(II) kept low at 10.5 %. The back-extraction efficiency of Co(II) reached 99.53 %. The responsive mechanism was studied by measuring the dynamic interfacial tension and interfacial dilatational rheology of CTAB solution in heptane under the effects of NaCl, DMEA and pH. By pH stimulus, DMEA protonated and increased the ionic strength, consequently inducing a “salting-out” effect and deactivating CTAB at oil-water interface, ultimately destabilizing the microemulsion. This study proposes a new approach for constructing responsive microemulsions for recovering heavy metals and also provides useful information on its responsive mechanisms by establishing a relationship between interfacial property and macroscopic stability of microemulsions.

Experimental studies on the interfacial shear characteristics between joint concrete and foamed polymer in cross-river shield tunnel

The inadequate grouting performance in cross-river shield tunnels is primarily due to the insufficient bonding strength between the grouting material and the tunnel segments. In this study, a series of tests were conducted to compare foamed polymer and common grouting materials, focusing on the tangential bonding performance of the interface with tunnel segment concrete under varying humidity conditions. The applicability of polymer for treating leaks in cross-river shield tunnels was explored. The effects of polymer density, interfacial humidity, interfacial roughness, and normal stress on the shear strength of the polymer-concrete interface were investigated. A mathematical model reflecting the interface shear characteristics between polymer and concrete was established and validated. The test results have shown that, due to the fast reaction speed and high expansion rate, foamed polymer was found to be a feasible solution for addressing leakage in cross-river shield tunnels. Compared with common grouting materials, the density of foamed polymer is controllable, and the shear strength between foamed polymer and concrete segments is less affected by humid conditions. The minimum shear strength of the interface between foamed polymer and concrete is 1.2 MPa, while the maximum is 2.0 MPa. Foamed polymer can meet the needs of leakage treatment of cross-river shield tunnel. The interfacial shear strength between foamed polymer and concrete segments is directly proportional to the polymer density, interfacial roughness, and normal stress, and inversely proportional to the level of humid in the tunnel. The influence of various factors on interfacial strength is ranked as follows: polymer density > interfacial humidity > normal pressure > interfacial roughness. The residual error of linear regression mathematical model for the shear strength of interface between foamed polymer and segment concrete follows a normal distribution. The fitting results were proven to be accurate, allowing for the intuitive prediction of the quantitative relationship between shear strength and multiple influencing factors.

Combining Enhanced Resolving Power with Duty Cycle Improvements on a Multi-Reflecting Time-of-Flight Mass Spectrometer.

The combination of enhanced resolving power and improved duty cycle on a multireflecting time-of-flight mass spectrometer is described. Resolving power increases are achieved by extending the effective ion path length from 47 m to greater than 200 m. Path length increases are achieved through containment of ions within the analyzer for up to N = 5 passes using a pulsed deflection electrode. Resolving power was shown to increase from 220,000 to 402,000 (fwhm) at m/z 785 for N = 1 and N = 4 analyzer passes, respectively. Due to the timing of the pulsed deflection electrode, the approach is particularly suited to high resolution analysis over a targeted m/z range. Duty cycle enhancements are achieved for ions of the targeted m/z range via accumulation prior to orthogonal acceleration, providing signal improvements of 2 orders of magnitude. Achieving such high resolving powers at fast scan rates (30 Hz) can yield additional information such as fine isotope structure; when combined with ppb mass measurement accuracy, high confidence in analyte identification can be achieved. The technique is applied for N = 2 analyzer passes, demonstrating fine isotope structure for a typical UHPLC metabolite identification experiment at a 10 Hz acquisition rate. Additionally, mass spectrometry imaging data is acquired using DESI, demonstrating the improved image clarity achieved at >300,000 (fwhm).

ƩS COVID-19 is a rapid high throughput and sensitive one-step quadruplex real-time RT-PCR assay

Real-time reverse transcription polymerase chain reaction (RT-PCR), a standard method recommended for the diagnosis of coronavirus disease 2019 (COVID-19) requires 2–4 h to get the result. Although antigen test kit (ATK) is used for COVID-19 screening within 15–30 min, the drawback is its limited sensitivity. Hence, a rapid one-step quadruplex real-time RT-PCR assay: termed ƩS COVID-19 targeting ORF1ab, ORF3a, and N genes of SARS-CoV-2; and Avocado sunblotch viroid (ASBVd) as an internal control was developed. Based on strategies including designing high melting temperature primers with short amplicons, applying a fast ramp rate, minimizing hold time, and reducing the range between denaturation and annealing/extension temperatures; the assay could be accomplished within 25 min. The limit of detection of ORF1ab, ORF3a, and N genes were 1.835, 1.310, and 1 copy/reaction, respectively. Validation was performed in 205 combined nasopharyngeal and oropharyngeal swabs. The sensitivity, specificity, positive predictive value, and negative predictive value were 92.8%, 100%, 100%, and 97.1%, respectively with 96.7% accuracy. Cohen’s Kappa was 0.93. The newly developed rapid real-time RT-PCR assay was highly sensitive, specific, and fast, making it suitable for use as an alternative method to support laboratory diagnosis of COVID-19 in outpatient and emergency departments.

Linker Conformation Controls Oxidation Potentials and Electrochromism in Highly Stable Zr-Based Metal-Organic Frameworks.

The development of tailor-made electrochromic (EC) materials requires a large variety of available substances with properties that precisely match the task. Since the inception of electrochromic metal-organic frameworks (MOFs), the field relies only on a limited set of building blocks, providing the desired electrochromic effect. Herein, we demonstrate for the first time the implementation of a Piccard-type system (N,N,N',N'-benzidinetetrabenzoate) into Zr-MOFs to obtain electrochromic materials. With fast switching rates, high contrast ratio, long-life stability, and exceptional chemical and physical stability, the novel material is on par with inorganic EC material. The new EC system exhibits an ultrahigh contrast from the bleaching state, with transmittance in the visible region >53%, to the colored state with a transmittance of ca. 3%. The 5 μm thick film attained up to 90% of the coloring in 12.5 s and exhibited high electrochemical reversibility. Moreover, the conformational lability of the electrochromic ligand chosen is locked via the topology design of the framework, which is not attainable in the solution. Locked conformations of the redox active linker in distinct polymorphous frameworks (DUT-65 and DUT-66) feature different redox characteristics and opens the door to the overarching control of the oxidation pathway in the Piccard-type systems.

Bioinspired hierarchical and dual-morphology humic-acid/pectin/chitosan composite aerogels for efficient removal of pollutants from wastewater

How to solve the contradiction between the efficiency and adsorption rate of porous materials in adsorbing pollutants has always been one of the focus issues. In this study, the small landscape cypress trees structure like biomimetic of a hierarchical and dual morphology 3D porous HA-based aerogel was designed and synthesized to use humic acid (HA), pectin (PE) and chitosan (CTS) as raw materials, which it was formed by the disorderly overlapping of lamella composed of fiber networks in 3D space. Due to its special microstructure, it can be used like separation membrane, which allowing for rapid adsorption of pollutants in the water while the water flow passes through quick. In general, this work provides a new concept for owning fast adsorption rate and efficient adsorption of porous materials of preparation to use green method.

Tetrazole and Oxadiazole Derivatives as Thermally Activated Delayed Fluorescence Emitters.

Organic light-emitting diodes (OLEDs) are promising lighting solutions for sustainability and energy efficiency. Incorporating thermally activated delayed fluorescence (TADF) molecules enables OLEDs to achieve internal quantum efficiency (IQE), in principle, up to 100 %; therefore, new classes of promising TADF emitters and modifications of existing ones are sought after. This study explores the TADF emission properties of six designed TADF emitters, examining their photophysical responses using experimental and theoretical methods. The design strategy involves creating six distinct types of a donor-acceptor (D-A) system, where tert-butylcarbazoles are used as donors, while the acceptor component incorporates three different functional groups: nitrile, tetrazole and oxadiazole, with varying electron-withdrawing character. Additionally, the donor-acceptor distance is adjusted using a phenylene spacer, and its influence on TADF functionality is examined. The clear dependency of an additional spacer, inhibiting TADF, could be revealed. Emitters with a direct donor-acceptor connection are demonstrated to exhibit TADF moderate emissive behavior. The analysis emphasizes the impact of charge transfer, singlet-triplet energy gaps (ΔEST), and other microscopic parameters on photophysical rates, permitting TADF. Among the emitters, TCz-CN shows optimal performance as a blue-green emitter with an 88 % photoluminescence quantum yield (PLQY) and fast rate of reversible intersystem crossing of 2×106 s-1 and 1×107 s-1, obtained from time-resolved photoluminescence (TRPL) experiment in PMMA matrix and quantum mechanical calculations, respectively. This comprehensive exploration identifies molecular bases of superior TADF emitters and provides insights for future designs, advancing the optimization of TADF properties in OLEDs.

Synergistic Triple-Action morphological composite Anode: Integrating lattice Softening, Interfacial electric Fields, and dual confinement for superior Potassium-Ion battery performance

Synergistic effects could significantly improve slow redox kinetics and structural pulverization of electrodes in potassium ion batteries (PIBs); however, the performance of single synergistic designs is limited. Multi-synergistic composite, shaped by a blend of factors, substantially boosts performance, yielding outcomes that surpass single synergistic coupling design. Herein, we develop a Bi2Se3/Sb2Se3@NC@G electrode that integrates three key features for enhanced potassium-ion storage: p-n junctions enhance electron transfer through internal electric fields, dual confinement prevents K2Se dissolution into the electrolyte, and lattice softening in the Bi-Sb alloy relieves stress during potassium ion insertion/extraction. These multi-synergistic effects enable the heterostructure to exhibit superior electrochemical performance in potassium-ion batteries.The Bi2Se3/Sb2Se3@NC@G electrode demonstrates notable capacity of 640 mA h g-1 at current density of 50 mA g-1, achieving 95.5 % of its theoretical capacity, maintain stable capacity of 310 mA h g−1 after 5000 cycles at current density of 0.5 A/g with 0.002 % per cycle degradation, and exhibits the fastest rate capability up to 10 A/g (172 mA h g−1). Furthermore, potassium ion hybrid capacitor (PIHC) can achieve a high energy density of 118 Wh kg−1 and a power density of 5200 W kg−1, and full cell shows an attractive energy density of 97 Wh kg-1 and a stable performance after 250 cycling number under 1 A g-1. This study proposes an effective strategy that employs multiple synergistic coupling designs to maximize potassium-ion storage capacity, achieving a breakthrough in extending battery lifecycle.

A Harmony-Based Approach for the Evaluation and Regulation of Water Security in the Yellow River Water-Receiving Area of Henan Province

Water security, as a crucial component of national security, plays a significant role in maintaining regional stability and ensuring the healthy and rapid development of the economy and society. The Yellow River water-receiving area of Henan Province (YRWAR-HN) is selected as the research area in this study. Firstly, a comprehensive evaluation index system is constructed based on the actual water security problems of the research area, and the single index quantification–multiple indices syntheses–poly-criteria integration method (SMI-P) is introduced to quantify the water security degree of 14 cities in the YRWAR-HN from 2010 to 2021. Then, the obstacle degree model is used to identify the key obstacle indexes that restrict the improvement of water security. Finally, the harmonious behavior set optimization method is adopted to carry out the regulation of water security, and the improvement path of water security in the YRWAR-HN is formulated. The results indicate the following: (1) the water security degree of the YRWAR-HN shows a fluctuating upward trend, increasing from 0.4348 (2010) to 0.6766 (2021), a significant rise of 55.61%. The water security level improves from the relatively unsafe level to the relatively safe level. Hebi City exhibits the fastest rate of water security improvement, while Xinxiang City shows the slowest rate. (2) The density of the river network (X1) and the proportion of investment in water conservancy and environmental protection in the total investment (X15) are the two indexes with the highest obstacle degree, with the average obstacle degrees being 15.09% and 10.79%, respectively. (3) The combination of the composite regulation scenario and improvement Path 2 is the optimal regulation strategy for water security in the YRWAR-HN. From the implementation process, Luoyang, Sanmenxia, Jiyuan, Xuchang, and Shangqiu may prioritize improving their flood and drought disaster defense capabilities and emergency response capabilities, continuously enhancing the flood prevention and disaster reduction system. Zhengzhou, Kaifeng, Xinxiang, Jiaozuo, Anyang, Hebi, Pingdingshan, and Zhoukou may prioritize resolving the regional water supply and demand conflicts, balancing development and conservation, actively seeking transboundary and external water transfers, and strengthening the capacity for water conservation and intensive utilization. Puyang City may prioritize enhancing its comprehensive water environment management capabilities, increasing investment in water conservancy and the environment, improving production processes, reducing pollutant emissions, and mitigating agricultural non-point source pollution.

Vertical Green Wall Systems for Rainwater and Sewage Treatment

Rainwater and sewage are important pollution sources for surface water bodies. Vertical greening systems (VGSs) are extensively employed for these wastewater treatments due to the green and sustainable characteristics, as well as their high-efficiency in pollutant (organic matter, nitrogen, and phosphorus) removal. At present, more and more VGSs are designed with green buildings, serving city ecosystems. This study provides an overview of different kinds of VGSs for rain and sewage treatment, emphasizing their types, design, mechanisms, selection of plants, and growth substrate. Plants play a crucial role in pollutant removal, and different plants usually obtain different efficiencies of water treatment. Climbing plants and ornamental plants with fast growth rates are priority selections for VGSs, including Canna lilies, Jasmine, Grape vine, Boston ivy, Pittosporum tobira, Pelargonium australe, Mentha aquatica, and Lythrum salicaria. The substrate is the most critical part of the VGS, which plays an important role in regulating water flow, supporting plant growth, promoting biofilm growth, filtering pollutants, and adsorbing nutrients. The single substrate either has a blockage problem or has a short holding time. Therefore, a number of studies have mixed the substrates and integrated the advantages of the substrates to form a complementary effect, thereby improving the overall purification efficiency and stability. Novel substrates (sand, spent coffee grounds, date seeds, coffee grinds, reed-based, etc.) are usually mixed with coco coir, light-weight expanded clay, growstone, or perlite at a certain ratio to obtain optimum treatment performance. Moreover, plants in clay show more significant growth advantages and health statuses than in zeolite or soil. Operating parameters are also significant influences on the treatment performance. This review provides theoretical and technical support for designing sustainable, environmentally friendly, and cost-effective VGSs in treating rainwater and sewage.

Assessing Species-Level Identification of Some Cryptic Frog Species of Bangladesh Using 16s and 12s Rrna Genes

In recent years, a number of new and undescribed anuran species are being discovered at a very fast rate in South and Southeast Asia. With the revelation of more and more species that were previously considered to be some other species, accurate identification of these morphologically cryptic anurans based on morphology alone have become difficult. In this study, we attempted specieslevel identification of 15 frog specimens belonging to the families Dicroglossidae and Microhylidae of Bangladesh by analyzing their 16S and 12S rRNA gene sequences. The collected specimens were successfully identified to be belonging to eight different species, namely Fejervarya dhaka, F. asmati, F. pierri and F. orissaensis; Euphlyctis kalasgramensis and Euphlyctis sp.; Microhyla berdmorei and M. mymensinghensis using BLAST and maximum likelihood analyses. In some cases the frog samples showed morphological resemblance but after molecular analysis they were found to be different and in another case morphologically distant samples were found to be molecularly similar. For example, two of the specimens (ESP 01, ESP 02) turned out to be E. kalasgramensis at molecular analysis, however, did not match with the morphological and morphometric descriptions (specially snout-vent length) described previously. Moreover, a species is suspected to be still undescribed and another species namely M. berdmorei was thought to be absent in Bangladesh which has been recorded in our study. Thus, morphological ambiguity strengthens the urge for molecular analysis for proper identification. Dhaka Univ. J. Biol. Sci. 33(2): 27-52, 2024 (July)

Communication‐Efficient Distributed Estimation of Causal Effects With High‐Dimensional Data

ABSTRACTWe propose a communication‐efficient algorithm to estimate the average treatment effect (ATE), when the data are distributed across multiple sites and the number of covariates is possibly much larger than the sample size in each site. Our main idea is to calibrate the estimates of the propensity score and outcome models using some proper surrogate loss functions to approximately attain the desired covariate balancing property. We show that under possible model misspecification, our distributed covariate balancing propensity score estimator (disthdCBPS) can approximate the global estimator, obtained by pooling together the data from multiple sites, at a fast rate. Thus, our estimator remains consistent and asymptotically normal. In addition, when both the propensity score and the outcome models are correctly specified, the proposed estimator attains the semi‐parametric efficiency bound. We illustrate the empirical performance of the proposed method in both simulation and empirical studies.

Thermosensitive Liposomes for Gemcitabine Delivery to Pancreatic Ductal Adenocarcinoma.

Treatment of pancreatic ductal adenocarcinoma with gemcitabine is limited by an increased desmoplasia, poor vascularization, and short plasma half-life. Heat-sensitive liposomes modified by polyethylene glycol (PEG; PEGylated liposomes) can increase plasma stability, reduce clearance, and decrease side effects. Nevertheless, translation of heat-sensitive liposomes to the clinic has been hindered by the low loading efficiency of gemcitabine and by the difficulty of inducing hyperthermia in vivo. This study was designed to investigate the effect of phospholipid content on the stability of liposomes at 37 °C and their release under hyperthermia conditions; this was accomplished by employing a two-stage heating approach. First the liposomes were heated at a fast rate, then they were transferred to a holding bath. Thermosensitive liposomes formulated with DPPC: DSPC: PEG2k (80:15:5, mole%) exhibited minimal release of carboxyfluorescein at 37 °C over 30 min, indicating stability under physiological conditions. However, upon exposure to hyperthermic conditions (43 °C and 45 °C), these liposomes demonstrated a rapid and significant release of their encapsulated content. The encapsulation efficiency for gemcitabine was calculated at 16.9%. Additionally, fluorescent analysis during the removal of unencapsulated gemcitabine revealed an increase in pH. In vitro tests with BxPC3 and KPC cell models showed that these thermosensitive liposomes induced a heat-dependent cytotoxic effect comparable to free gemcitabine at temperatures above 41 °C. This study highlights the effectiveness of the heating mechanism and cell models in understanding the current challenges in developing gemcitabine-loaded heat-sensitive liposomes.

Ultrastructural and thermal analyses reveal novel insights into low-temperature survival mechanisms of hydrated seeds of Poaceae species from alpine regions

Global warming leads to snow cover loss in the alpine ecosystem, exposing seeds to extreme diurnal temperature fluctuations during the growing season. The risk of freezing increases as seeds have increased moisture content. Studying the survival mechanisms of seeds at low temperatures can help analyze changes in alpine meadow populations and target conservation efforts. Here, we used three species of Poaceae as a model to understand freezing stress.Fully imbibed Elymus dahuricus, Festuca elata, and Lolium multiflorum seeds were subjected to programmed cooling at fast and slow rates (-1.0/0.05°C/min) and then assessed for survival. Differential Scanning Calorimetry was used to analyze thermal transitions during cooling. HE-stained paraffin sections and a Transmission Electron Microscope were employed to observe internal morphology and ultrastructural changes.E. dahuricus seeds exhibited greater tolerance to low temperatures than those of the other two species, with an LT50 of approximately -20°C for both cooling rates and maintained relatively intact ultrastructure. The observed Low-temperature exotherm (LTE) correlated with seed survival, with viability decreasing extensively below LTE.Fast cooling caused fewer changes to seed morphology and ultrastructure than slow cooling, suggesting that the primary survival mechanism during fast cooling is freezing avoidance through supercooling. Seeds exhibited greater freeze tolerance under slow than fast cooling, primarily by migrating intracellular water to extracellular spaces where it froze, causing considerable damage to cell ultrastructure and forming apparent cavities in some seeds.

In Vivo Three-Dimensional Geometric Reconstruction of the Mouse Aortic Heart Valve.

Aortic valve (AV) disease is a common valvular lesion in the United States, present in about 5% of the population at age 65 with increasing prevalence with advancing age. While current replacement heart valves have extended life for many, their long-term use remains hampered by limited durability. Non-surgical treatments for AV disease do not yet exist, in large part because our understanding of AV disease etiology remains incomplete. The direct study of human AV disease remains hampered by the fact that clinical data is only available at the time of treatment, where the disease is at or near end stage and any time progression information has been lost. Large animal models, long used to assess replacement AV devices, cannot yet reproduce AV disease processes. As an important alternative mouse animal models are attractive for their ability to perform genetic studies of the AV disease processes and test potential pharmaceutical treatments. While mouse models have been used for cellular and genetic studies of AV disease, their small size and fast heart rates have hindered their use for tissue- and organ-level studies. We have recently developed a novel ex vivo micro-CT-based methodology to 3D reconstruct murine heart valves and estimate the leaflet mechanical behaviors (Feng et al. in Sci Rep 13(1):12852, 2023). In the present study, we extended our approach to 3D reconstruction of the in vivo functional murine AV (mAV) geometry using high-frequency four-dimensional ultrasound (4DUS). From the resulting 4DUS images we digitized the mAV mid-surface coordinates in the fully closed and fully opened states. We then utilized matched high-resolution µCT images of ex vivo mouse mAV to develop mAV NURBS-based geometric model. We then fitted the mAV geometric model to the in vivo data to reconstruct the 3D in vivo mAV geometry in the closed and open states in n = 3 mAV. Results demonstrated high fidelity geometric results. To our knowledge, this is the first time such reconstruction was ever achieved. This robust assessment of in vivo mAV leaflet kinematics in 3D opens up the possibility for longitudinal characterization of murine models that develop aortic valve disease.

Rational modulation of covalent organic frameworks heterogeneous catalyst: Structural cationization effect on accelerating photocatalytic oxidation process

Photocatalytic technology has been playing a key role in energy conversion and environmental remediation. It is critical and challenging that understanding and modulating the local structure effect on accelerating each rate-dependent step during the photocatalytic process. Herein, we utilize the highly ordered and structurally tunable COFs as a favorable platform for integrating multiple modulations of photochemical properties, including light capture, exciton dissociation, charge separation, and mass transfer by structural cationization strategy. Moreover, it is found that the cationized COF has a strong enrichment ability on the sulfide substrates, exhibiting an extremely fast selective oxidation rate of sulfides even in air. The calculation results indicate that the structural cationization successfully aggregates reaction substrates and increases the molecular collision probability, generating a reaction environment to promote the photocatalytic performances. This study will be expected to facilitate the new insights for the exploration of highly active COFs heterogeneous photocatalysts.

Enhancement of Photoelectric Conversion Efficiency in Dye-Sensitized Solar Cells Using SnO2–TiO2 Composite Nanofibers

SnO2 is a wide-band gap N-type semiconductor material with a higher electron transfer rate than TiO2. Therefore, SnO2 has broad application prospects in the photoanode composite materials of dye-sensitized solar cells (DSSC). In this study, SnO2–TiO2 composite nanofibers with different molar ratios (5%, 10%, 15%, and 20%) were prepared by double-needle electrospinning technology, and the nanofibers were characterized after adjusting the solution composition. Different molar ratios of TiO2 and SnO2–TiO2 composite nanofiber photoanodes were fabricated by spin-coating, and the adsorption behavior of dyes on the photoanodes was investigated. Moreover, the electrochemical impedance of the photoanodes and DSSC and their photoelectric performance were also tested. The experimental results showed that SnO2–TiO2 composite nanofibers with a molar ratio of 10% exhibited excellent properties, including a peak specific surface area of 93.01 m2/g, strong dye adsorption capacity, small interfacial resistance, and fast electron transfer rate. These outstanding properties significantly promoted the generation of photoelectrons and improved the photoelectric conversion efficiency of DSSC. Compared with single-component TiO2, the photoelectric conversion efficiency of SnO2–TiO2 nanofiber photoanode composite material improved by 85.65%.

Facile construction of ZnWO4/g-C3N4 heterojunction for the improved photocatalytic degradation of MB, RhB and mixed dyes

This study presents the construction of binary ZnWO4/g-C3N4 nanocomposite via a facile hydrothermal approach to enhance the photocatalytic performance under the visible light irradiation. The proposed ZnWO4/g-C3N4 nanocomposite photocatalyst shows excellent photodegradation towards organic dyes, such as methylene blue (MB) and rhodamine B (RhB). The optimal loading of ZnWO4 and g-C3N4 leads to the synergistic effect which plays a predominant role in inhibiting the fast electron-hole pairs recombination rate at the interface of ZnWO4/g-C3N4 photocatalyst. The degradation rates of MB and RhB is achieved around 92.9 % and 88.8 % under the visible light irradiation for 120 min. According to our findings, the radical quenching experiments suggested that the ●OH radicals played a positive impact in the photodegradation process. Since, our proposed photocatalyst exhibit superior photocatalytic activity towards the individual MB and RhB degradation. The ZnWO4/g-C3N4 photocatalyst were further applied to demonstrate the degradation of mixed dyes (MB and RhB) at an irradiation time of 180 min. In the mixed dye solution, the ZnWO4/g-C3N4 photocatalyst achieved a highest reaction rate of 0.010 min−1 for MB and 0.012 min−1 for RhB with the degradation rate of 87.8 % and 83.3 % for RhB and MB, respectively. For the mixed dyes, the radical quenching experiments confirmed that the ●OH radicals are responsible for the fast photodegradation. Additionally, the practicality of the proposed ZnWO4/g-C3N4 photocatalyst towards the degradation of MB, RhB and the mixed dyes were examined in the tap water samples. Furthermore, the plausible photodegradation mechanism of ZnWO4/g-C3N4 photocatalyst was proposed in detail. This study provides a new insight for the simultaneous degradation of mixed chemical pollutants using our proposed ZnWO4/g-C3N4 photocatalyst.