Poor Separation Research Articles

Integrating interface engineering and plasmonic effect to boost photoresponse performance of ZnO:Ga/GaN heterojunction self-powered UV photodetectors

The ability to function without an external power supply makes photodetectors highly promising for use in a new generation of wirelessly and independently operated ultraviolet (UV) photodetection and imaging systems. However, self-powered photodetectors' high dark current, inadequate light harvesting, and poor carrier separation prevent them from attaining high-efficiency UV photodetection and imaging. Herein, a high-performance heterojunction UV photodetector consisting of a single Ga-doped ZnO microwire enshrouded by Ag nanowires (AgNWs@ZnO:Ga MW), a MgO electron blocking layer, and a p-type GaN wafer was proposed. Taking full advantage of the interface engineering and plasmonic effects, the AgNWs@ZnO:Ga MW/MgO/GaN photodetector achieves high photodetection performance with an excellent responsivity of 262 mA/W, a remarkable external quantum efficiency of 92.37%, and a high detectivity of 1.966 × 1012 Jones under 370 nm illumination with power density of 0.22 mW/cm2. Furthermore, it also demonstrates ultrafast pulsed photoresponse speed with a rise/fall time of 3.64 μs/252 μs. An UV imaging system is designed based on the AgNWs@ZnO:Ga MW/MgO/GaN self-powered photodetector, allowing for high-quality, accurate, and distinct object imaging. This work combines interface engineering and plasmonic effects for achieving high-performance UV photodetection, which provides a strategic approach to the development of highly efficient optoelectronic devices.

High performance mixed-dimensional assembled MXene composite membranes for molecular sieving

Two-dimensional (2D) separation membranes have proved their superiorities in addressing global water scarcity and recycling resources. However, current 2D membranes usually suffer from swelling and irregular stacking issues, which result in poor separation performance. Herein, we developed novel mix-dimensional assembled MXene composite membranes with high permeability and selectivity by intercalating 1D carboxylated cellulose nanofibers (CNFs) into 2D lamellar MXene nanosheets. The effects of chain length of CNFs and MXene/CNFs mass ratios on the morphologies, physicochemical properties, and separation performances of composite membranes were systematically investigated. The optimized MXC-3-L membrane exhibited superior rejection to Congo red (CR, >99%) and remarkable separation efficiency of dye/salt. The separation factors for the CR/NaCl and CR/Na2SO4 mixtures were 512.0 and 517.2, respectively. Moreover, the MXC-3-L membrane showed distinct rejections to perfluoroalkyl substances (PFAS) (>95%) with a nearly 8-fold increase of permeance in comparison with the commercial polyamide membrane. The 2D X-ray diffraction analysis verified that the intercalation of 1D CNFs into 2D MXene nanosheets via strong hydrogen bonding can regulate the nanochannel into more stable and regularly stacking lamellar structures, which plays a key role in high permeance and excellent molecular separation efficiency. In addition, 1D CNFs play an essential role as “threading” and “stitching”, shielding the defects between adjacent MXene nanosheets and improving the separation efficiencies. Our work provides new insights into design of defect-free and highly selective 2D materials-based membranes for enhanced wastewater treatment and molecular sieving.

Decoupling synthesis and crystallization of covalent organic frameworks (COFs) for more crystalline layer targeting high efficiency dye separation

Covalent organic frameworks (COFs) are crystalline porous materials composed of organic building blocks linked by covalent bonds, which have attracted great attention for membrane–based separation applications. However, fabrication of COF membranes with high quality and performance remains a challenge, especially for the β–ketoenamine linked COFs. In the conventional IP methods, the synthesis process (the Schiff–base reaction of the monomers and the tautomerism of the oligomers) and the crystallization process (the self–assembly of the oligomers) of the COFs materials occur simultaneously on the surface of the support membrane, which can result in low crystallinity, high defect density, and poor separation performance of the COF layer. In this study, a novel strategy for fabricating large-area, defect–free COFs composite membranes by interfacial polymerization (IP) was presented to overcome this problem. By incorporating both the amine and aldehyde monomers in one organic phase, and dissolving organic acid catalyst in another phase (the water), the synthesis process mostly take place in the bulk of the organic phase, while the crystallization occurs on the surface of the support membrane under the influence of the organic acid catalyst. This strategy effectively decoupled the synthesis process with the crystallization, providing a stable growth region for crystalline layer, ultimately leading to the formation of a thin, defect–free and highly ordered COF layer on the support membrane. The strategy was demonstrate by synthesis of triformylphloroglucinol phenylenediamine (TpPa)–Ⅱ/Poly(m–phenylene isophthalaminde) (PMIA) composite membrane. We characterize the structure and morphology of the TpPa–Ⅱ/PMIA composite membrane by various analytical techniques to verify our hypothesis, and evaluate its separation performance using pure water permeance and dyes retention rate as indicators. The results show that the TpPa–Ⅱ/PMIA composite membrane has an 80 nm thick top-layer with regular COF structure and orderly pores. It exhibits an excellent dye separation performance, with a (pure water permeance) PWP of 105.6 L·m−2·h−1·bar−1 and CR rejection of 99.2 %, which surpasses most of the TpPa–type COFs composite membranes reported in literature, as well as the reference (TpPa–I/PMIA membrane) in this work. Moreover, the TpPa–Ⅱ/PMIA composite membrane maintains both its performance and structural stability during a 240–hour cross–flow filtration of the dye solution, demonstrating its excellent potential in the dye wastewater treatment.

Preparation of Ordered Macroporous ZIF-8-Derived Magnetic Carbon Materials and Its Application for Lipase Immobilization

Metal–organic framework materials (MOFs) and their derivatives are considered ideal immobilization carrier materials because of their large specific surface area, high porosity and excellent structural designability. Among them, ZIF-8 has great potential for immobilization of enzymes due to mild synthesis conditions, and good biocompatibility. However, conventional ZIF-8 crystals have poor separation and recovery efficiency due to their small pore size and poor acid stability, greatly limiting their application in enzyme immobilization and further application. Although the carbonization of ZIF-8 by pyrolysis has been shown to be one of the approaches that can enhance its chemical stability, this still does not effectively solve the problem of the difficulty of recycling. Herein, we developed a strategy of pre-carbonization immersion (immersion in aqueous FeSO4 solution before carbonization) to synthesize ordered macroporous ZIF-8-derived carbon materials with stable ferromagnetism (denoted as CZ-x-M-y, where x denotes the carbonization temperature and y denotes the concentration of the impregnated FeSO4 solution) and used them to immobilize lipases for biodiesel production. XRD analysis showed that the magnetic properties in the materials came from Fe3C species. We found that the magnetic carbon materials obtained by carbonization at 600 °C showed the best immobilization effect, where CZ-600-M-0.3 (using 0.3 mol·L−1 FeSO4 aqueous solution to soak ZIF-8 and carbonized at 600 °C) had the highest enzyme loading of 183.04 mg·g−1, which was 49.7% higher than that of the non-magnetic CZ-600. In addition, CZ-600-M-0.5 maintained the highest enzyme activity, which was 81.9% of the initial activity, after five batches of reuse. The stable magnetic support materials reported in this study have promising potential for the industrial application of immobilized lipase.

2D/2D ultrathin polypyrrole heterojunct aerogel with synergistic photocatalytic-photothermal evaporation performance for efficient water purification

Green photocatalysis has played a crucial role in resolving energy shortage and wastewater treatment. However, poor photogenerated electron-hole separation efficiency is still a great challenge. Notably, the thermal energy generated by photothermal materials through photothermal conversion provides a greater concentration of energy for the separation and utilization of the photoexcited electron-hole. Herein, we prepare 2D/2D reduced graphene oxide/polypyrrole (c-GPP) aerogel with both photocatalytic degradation and photothermal evaporation performance via interface-confined synthesis. The broad spectral response of rGO and PPy endows the aerogel excellent light-harvesting capabilities and facilitates the generation of photogenerated carriers. The π-π interaction between rGO and PPy give rise to built-in electric fields and electron delocalization effects, resulting in excellent photogenerated electron-hole separation efficiency. The aerogel shows excellent degradation of dyes and antibiotics under natural sunlight irradiation (up to 97 % degradation of dyes). In addition, the c-GPP exhibits a satisfactory photothermal evaporation rate of 1.59 kg m−2 h−1 and photothermal evaporation efficiency of 92.52 %. This work provides an effective route for solar-driven photocatalysis-photothermal synergy for efficient and sustainable water purification.

Determining the accuracy and suitability of common analytical techniques for sophorolipid biosurfactants.

To determine the performance of a sophorolipid biosurfactant production process, it is important to have accurate and specific analytical techniques in place. Among the most popular are the anthrone assay, gravimetric quantification (hexane:ethyl acetate extraction), and high-performance liquid chromatography (HPLC). The choice of analytical tool varies depending on cost, availability, and ease of use; however, these techniques have never been compared directly against one another. In this work, 75 fermentation broths with varying product/substrate concentrations were comprehensively tested with the 3 techniques and compared. HPLC-ultraviolet detection (198nm) was capable of quantifying C18:1 subterminal hydroxyl diacetylated lactonic sophorolipid down to a lower limit of 0.3g/L with low variability (<3.21%). Gravimetric quantification of the broths following liquid:liquid extraction with hexane and ethyl acetate showed some linearity (R2=.658) when compared to HPLC but could not quantify lower than 11.06g/L, even when no sophorolipids were detected in the sample, highlighting the non-specificity of the method to co-extract non-sophorolipid components in the final gravimetric measure. The anthrone assay showed no linearity (R2=.129) and was found to cross-react with media components (rapeseed oil, corn steep liquor, glucose), leading to consistent overestimation of sophorolipid concentration. The appearance of poor biomass separation during sample preparation with centrifugation was noted and resolved with a novel sample preparation method with pure ethanol. Extensive analysis and comparisons of the most common sophorolipid quantification techniques are explored and the limitations/advantages are highlighted. The findings provide a guide for scientists to make an informed decision on the suitable quantification tool that meets their needs, exploring all aspects of the analysis process from harvest, sample preparation, and analysis.

CH3COONa·3H2O/flaky modified vermiculite composite phase change materials enhanced phase change behavior and thermal storage through curing lotus root starch modification

With the establishment of the basic policy of environmentally-friendly and resource-saving society, the energy storage technology using phase change materials (PCMs) as the medium has developed unprecedentedly. Hydrated salt PCMs plays a vital role due to its large latent heat density, wide range of phase transition temperature, and high thermal conductivity. However, the problems of low enthalpy, poor thermal stability and phase separation are critical drawbacks of composite phase change materials (CPCMs), which limited the extensive use in fields of energy storage. In this work, the flaky vermiculite (MEVM) was fabricated by the acid treatment and alkali leaching, and the cured lotus root starch (CLRS) was embedded and used to enhance the water holding capability of hydrated salts. A series of sodium acetate trihydrate (SAT)-CLRS/MEVM was prepared, and the form-stable composite phase change materials (SAT fs-CPCMs) were obtained. Results showed that the encapsulation capacity of SAT fs-CPCM with 2 wt% CLRS was 71.3 %, and the thermal enthalpy reached 180.1 J/g, which was 43.7 % higher than that of SAT/MEVM. The contact angle of the sample with H2O was 22.24°, which represented hydrophilicity. SAT fs-CPCM also had good thermal stability and thermal reliability. After 200 thermal cycles, the enthalpy loss of the SAT fs-CPCM was only 5.2 %, and the 200th enthalpy value was 173.72 J/g. In addition, Calculations indicated that there were hydrogen bonds and van der Waals weak interaction between SAT and CLRS. This work provides a new perspective for the improvement of the thermal properties of hydrated salt and offers a promising approach for the applications of PCMs in cost-effective energy storage.

Nanoplate-based digital PCR for highly sensitive pork DNA detection targeting multi-copy nuclear and mitochondrial genes

The inclusion of ingredients derived from pigs in highly processed consumer products poses a significant challenge for DNA-targeted analytical enforcement, which could be overcome by using digital PCR. However, most species detection methods use digital PCR to target single-copy nuclear genes, which limits their sensitivity. In this work, we examined the performance of a nanoplate-based digital PCR method that targets multi-copy nuclear (MPRE42) and mitochondrial (Cytb) genes. Poor separation of positive and negative partitions, as well as a ‘rain effect’ were obtained in the porcine-specific MPRE42 assay. Among the optimization strategies examined, the inclusion of restriction enzymes slightly improved the separation of positive and negative partitions, but a more extensive ‘rain effect’ was observed. The high copy number of the MPRE42 amplicon is hypothesized to contribute to the saturation of the positive signal. In contrast, the porcine-specific Cytb assay achieved perfect separation of positive and negative partitions with no ‘rain effect’. This assay can detect as little as 0.4 pg of pork DNA, with a sensitivity of 0.05% (w/w) in a pork-chicken mixture, proving its applicability for detecting pork in meat and meat-based products. For the MPRE42 assay, potential applications in highly degraded products such as gelatin and lard are anticipated.

Light concentration and electron transfer in plasmonic-photonic Ag,Au modified Mo-BiVO4 inverse opal photoelectrocatalysts.

Plasmonic photocatalysis based on metal-semiconductor heterojunctions is considered a key strategy to evade the inherent limitations of poor light harvesting and charge separation of semiconductor photocatalysts. It can be profitably combined with three-dimensional photonic crystals (PCs) that offer an ideal scaffold for loading plasmonic nanoparticles and a unique architecture to intensify photon capture. In this work, Mo-doped BiVO4 inverse opals were applied as visible light-responsive photonic hosts of Ag and/or Au plasmonic nanoparticles in order to exploit the synergy of plasmonic and photonic amplification effects with interfacial charge transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical contaminants under visible light. Photoelectrochemical evaluation indicated a major contribution from hot spot-assisted local field enhancement, most pronounced for Ag/Mo-BiVO4 PCs due to the spectral overlap of the localized surface plasmon resonance with the electronic absorption and blue-edge slow photon region of Mo-BiVO4 PCs, in contrast to weak plasmonic sensitization effects for the Au-modified PCs. The diverse band alignment at the metal-semiconductor interfaces resulted in the enhanced photoelectrocatalytic degradation of tetracycline broad spectrum antibiotic by Ag/Mo-BiVO4 and the refractory ibuprofen drug by (Ag,Au)/Mo-BiVO4, attributed to the enhanced charge separation by electron transfer toward Ag nanoparticles. Combination of visible light activated semiconductor PCs and plasmonic nanoparticles with suitable band alignment and photonic band gap may provide a versatile approach for the rational design of efficient plasmonic-photonic photoeletrocatalysts.

Advancing sustainable hybrid bitumen systems: A compatibilization solution by functionalized polyolefins for enhanced crumb rubber content in bitumen

Polymer waste pollution has a profound effect on the environment and, consequently, on the lifestyle of humankind. The massive production and disposal of cross-linked polymers clearly exemplify the challenges of recycling. Increasing efforts are being undertaken to introduce recycled polymers, especially crumb rubber (CR), into asphalt formulations. Due to the rather poor processability and phase separation associated with CR-modified bitumen (CRMB) compositions, a broader implementation of such concept is challenging unless an efficient compatibilizer is applied. Results from the study on usage of In-Reactor-Functionalized Polyolefins viz. poly(propylene-co-hex-1-ene-co-hex-5-en-1-ol) (FPP), demonstrated excellent compatibilizing ability in CRMB, allowing incorporation of up to 10 wt% of CR. This represents a significant improvement when compared to the best-in-class solutions. The FPP-containing products exhibit superior bulk, nanomechanical and rheological properties, as well as stability during binder annealing. Furthermore, the bitumen surface morphology is significantly improved. The polar groups present in the FPP create a thermo-reversible interpenetrating cross-linked network that provides mechanical integrity and contributes to the adhesion to different components of the modified bitumen at service temperatures, enhancing its processability. The exceptional compatibility of FPP in CRMB resulted in a significant increase in the Performance Grade of the hybrid system by 5 classes (88) compared to neat bitumen (58). Moreover, the best-performing composition fulfilled the low-temperature ductility specifications, withstanding deformation without fracturing or breaking up to a 400 mm elongation.

Nanostructured (oxy)nitrides controllably synthesized by flux-assisted nitridation for promoted photocatalytic water splitting

Flux-assisted nitridation is an effective method to develop (oxy)nitride photocatalysts with enhanced charge separation. Herein, the systematic illustration of (oxy)nitride photocatalysts for water splitting in such preparation approach is reviewed.

Improvement of performance of perovskite solar cells through BaTiO&lt;sub&gt;3&lt;/sub&gt; doping regulated built-in electric field

The preparation of hybrid perovskite solar cells is expensive and environmentally demanding. Carbon-based HTL-free perovskite solar cells (C-PSCs) have attracted much attention because they replace the expensive precious metal electrode and remove the poor stability of the hole transport material. However, the improvement of efficiency is hampered by poor carrier separation and transport performance within C-PSCs, while the enhancement of the built-in electric field can improve the carrier transport performance, thus enhancing photoelectric performance. The built-in electric field can be regulated by doping. The anomalous photovoltaic effect and the built-in electric field of ferroelectric material play an important role in the field of optoelectronics. In this work, a simple and effective method is developed to improve the performance of perovskite solar cells via the combination of internal doping of ferroelectric polymer and external control of electric field. Ferroelectric material barium titanate (BaTiO&lt;sub&gt;3&lt;/sub&gt;) powder is added into perovskite precursor solution as an additive to prepare C-PSCs, which can improve the perovskite film morphology, reduce the film defect density, and enhance the carrier transport performance of C-PSCs. The results show that when the addition of BaTiO&lt;sub&gt;3&lt;/sub&gt; is 1.0% (mass fraction), the perovskite film is uniform and dense, and the photoelectric conversion efficiency of the cell is the highest. After the forward voltage polarization treatment, the residual polarized electric field of ferroelectric material BaTiO&lt;sub&gt;3&lt;/sub&gt; increases the built-in electric field, which provides sufficient power for realizing carrier transport and extraction, thus inhibiting the occurrence of non-radiative recombination. At the same time, the depletion layer width is increased, and the reverse saturation current is reduced, so the cell performance is significantly improved. The optimal device efficiency is 9.02%. This work provides an efficient strategy for regulating the built-in electric field by doping perovskite absorption layer.

Learning a microlocal prior for limited-angle tomography

Abstract Limited-angle tomography is a highly ill-posed linear inverse problem. It arises in many applications, such as digital breast tomosynthesis. Reconstructions from limited-angle data typically suffer from severe stretching of features along the central direction of projections, leading to poor separation between slices perpendicular to the central direction. In this paper, a new method is introduced, based on machine learning and geometry, producing an estimate for interfaces between regions of different X-ray attenuation. The estimate can be presented on top of the reconstruction, indicating more reliably the separation between features. The method uses directional edge detection, implemented using complex wavelets and enhanced with morphological operations. By using convolutional neural networks, the visible part of the singular support is first extracted and then extended to the full domain, filling in the parts of the singular support that would otherwise be hidden due to the lack of measurement directions.

Vertical MOF film supported on an organic–inorganic mixed substrate for complex wastewater purification

Flexible metal–organic framework (MOF) films are greatly desired for the separation of hazardous molecules and ions from wastewater. The current MOF films are usually horizontally deposited on the substrates, and thus restricted by brittleness, low exposure of surface area, as well as poor separation functions. Here, an organic–inorganic mixed substrate is firstly fabricated by growing hydroxyapatite (HA) nanowire arrays on the cellulose fiber (CF). Subsequently, MIL-100(Fe) nanocrystals are assembled on the surfaces of HA nanowire arrays through a layer-by-layer manner, leading to a unique vertical MOF film. The resulting vertical MOF films show competitive advantages over the horizontal counterparts: (i) they show excellent flexibility and they are tolerant to serious physical damage; (ii) they have multiple separation functions including ion exchange of HA, excellent adsorption of MOFs, and strong electrostatic interaction of CF; and (iii) the agglomeration of MIL-100(Fe) nanocrystals is effectively suppressed. Therefore, the average roughness, specific surface area, and average pore size of films are optimized. As a result, the vertical MOF films show universal separation of positively/negatively-charged dyes and Pb2+ ion, with high removal rates of > 94 %. More appealing, the mixed pollutants in the complex wastewater can be one-step separated through the vertical MOF films, with high removal rates of > 96 %.

Electrochemical Reduction of Ytterbium in Non-Aqueous Solvents - Towards Production of Pure Medical Lutetium-177

In recent years targeted radionuclide therapy has become a topic of great interest as a growing number of cancers can potentially be treated with radionuclides like lutetium-177 and samarium-153. To facilitate this growth and meet the demand, preparation and purification of lutetium-177 is increasing in importance. In the most common production route, enriched ytterbium-176 targets are irradiated and the produced lutetium-177 is separated from the ytterbium target material. This challenging separation is commonly performed using ion exchange resins, a method limited in scalability as the chemical similarity between ytterbium and lutetium results in poor separation at higher concentrations.An alternative method to aid the separation of lutetium from ytterbium is the electrochemical reduction of ytterbium as a change in oxidation states changes chemical properties significantly. Ytterbium has an accessible divalent state, whereas lutetium has not. However, the very negative value of the Yb(III)/Yb(II) standard reduction potential (E0= -1.04 V vs. SHE) does pose some challenges as it becomes a necessity to work in non-aqueous solvents with a very low water content. Similar research has already been performed in our group, looking into the separation of samarium-153 from europium-154, reducing europium in nitrate media, followed by a separation over TEVA resin. In this study, we investigated the reduction of ytterbium in ethylene glycol, dimethyl sulfoxide, tetrahydrofuran and N,N-dimethyl formamide by cyclic voltammetry, linear sweep voltammetry and electronic impedance spectroscopy. The influence of multiple variables such as moisture content on the reduction kinetics and stability of Yb(II) was determined and a Koutecky-Levich analysis was performed. Our results demonstrate that the reduction of ytterbium in non-aqueous solvents is feasible but attempts to perform bulk electrolysis were not successful yet. Ethylene glycol, dimethyl sulfoxide and N,N-dimethyl formamide demonstrate favorable conditions and in each solvents clear reduction and oxidation peaks were observed. It was found that the solvents do affect the peak separation, reduction potential and sensitivity to passivation. Figure 1

Enhancing Mo leaching efficiency from spent catalyst via Fenton-like oxidation process: A comprehensive investigation of leaching effects, mechanism and environmental impacts

Spent hydrodesulfurization (HDS) catalyst contains considerable amounts of Mo, Ni and V, is an important secondary resource for these valuable metals. Direct acid solution leaching method exhibits poor separation effect from catalyst carrier for Mo due to greater stability of MoS2. This study explored Mo leaching efficiencies from spent HDS catalyst by Fenton-like oxidation systems (H2O2 and K2S2O8), which were frequently employed in the wastewater treatment. To further improve Mo leaching efficiency, nano zero-valent iron (nZVFe) was used to activate H2O2/K2S2O8 and produce more free radicals (·OH and ·SO4-). Approximate 96.0 % and 93.3 % of Mo were leached from spent HDS catalyst in nZVFe + H2O2 + H2SO4 and nZVFe + K2S2O8 + H2SO4 systems under optimal experimental conditions, increased by 16.2 % and 8.2 % than normal H2O2 (79.8 %) and K2S2O8 (85.1 %) system without nZVFe. The leaching process of Mo in both nZVFe + H2O2 + H2SO4 and nZVFe + K2S2O8 + H2SO4 systems conformed to the shrinkage core model. Kinetic analysis and molecular calculation demonstrated the leaching process of Mo in nZVFe + H2O2 + H2SO4 system was driven by chemical reaction and solid film diffusion, and the leaching and oxidation reactions of MoS2 occurred simultaneously. However, the leaching process of Mo in nZVFe + K2S2O8 + H2SO4 system was driven only by chemical reaction, solid MoS2 was firstly dissolved into Mo4+ by H+, and then oxidized into Mo6+ by ·SO4-. The economic and environmental impacts evaluation indicated that the separation of Mo from spent HDS catalysts by nZVFe + H2O2 + H2SO4 was assigned as a better choice than normal H2O2 and K2S2O8 system without nZVFe due to higher leaching efficiency and lower cost.

P-doped bismuth sulfide for improved photocatalytic degradation of bisphenol A: Role of built-in electric field and S vacancies

Efficient and stable photocatalytic materials are crucial for advancing photocatalytic technology. While bismuth sulfide has garnered significant attention in recent years, its poor electron-hole separation and rapid recombination have hindered its effectiveness. In this paper, a phosphorus (P)-doped bismuth sulfide is used to establish a ternary bismuth phosphosulfide (FGBS1-XPX) photocatalyst. The successful incorporation of P into bismuth sulfide was verified through SEM-EDX, XRD, and XPS analyses. The P doping generates a built-in electric field on the catalyst surface, which can effectively extract carriers. Additionally, it was demonstrated by Mott-Schottky test, EPR and PL that P doping shortens the gap between the catalyst's impurity energy level and Fermi energy level, making the S vacancies level an effective electron capture center. This results in improved separation efficiency of electron-hole pairs and a delay in the lifetime of charge carriers. The optimal degradation rate for a 15 ppm BPA solution using 0.6 g/L of 1FGBS1-XPX was 80% within 4 h, demonstrating significantly improved photocatalytic activity. This was due to the synergistic action of the built-in electric field and S vacancies induced by P doping. The idea of utilizing P doping and S vacancies synergism to enhance photocatalytic performance provides a new approach for designing photocatalysts with improved electron-hole separation.

Artificial Photosynthetic System with Spatial Dual Reduction Site Enabling Enhanced Solar Hydrogen Production.

Although S-scheme artificial photosynthesis shows promise for photocatalytic hydrogen production, traditional methods often overly concentrate on a single reduction site. This limitation results in inadequate redox capability and inefficient charge separation, which hampers the efficiency of the photocatalytic hydrogen evolution reaction. To overcome this limitation, a double S-scheme system is proposed that leverages dual reduction sites, thereby preserving energetic photo-electrons and holes to enhance apparent quantum efficiency. The design features a double S-scheme junction consisting of CdS nanospheres decorated with anatase TiO2 nanoparticles coupled with graphitic C3 N4 . The as-prepared catalyst exhibits a hydrogen evolution rate of 26.84mmolg-1 h-1 and an apparent quantum efficiency of 40.2% at 365 nm. This enhanced photocatalytic hydrogen evolution is ascribed to the efficient charge separation and transport induced by the double S-scheme. Both theoretical calculations and comprehensive spectroscopy tests (both insitu and exsitu) affirm the efficient charge transport across the catalyst interface. Moreover, substituting the reduction-type catalyst CdS with other similar sulfides like ZnIn2 S4 , ZnS, MoS2 and In2 S3 further confirms the feasibility of the proposed double S-scheme configuration. The findings provide a pathway to designing more effective double S-scheme artificial photosynthetic systems, opening up fresh perspectives in enhancing photocatalytic hydrogen evolution performance.

Effect of moisture content on charging and triboelectrostatic separation of coal gasification fine ash

Resource utilization of coal gasification fine ash is restricted by moisture content. Drying and dewatering are indispensable in triboelectrostatic separation. The study aims to determine the minimum required moisture content for effective gasification fine ash separation. Thereinto, experiments reveal a profound influence of moisture content on the electrical properties of gasification fine ash, subsequently impacting the separation process. With higher moisture content, the resistivity and relative dielectric constant of gasification fine ash decrease and increase, respectively. The electrical conductivity of gasification fine ash is enhanced by moisture, but the ability to retain charge is reduced, resulting in a decline in the charge-to-mass ratio. Additionally, severely agglomerated particles and poor separation will be generated by a high moisture content. Comprehensive triboelectrostatic separation experiments demonstrate that gasification fine ash with an additional moisture content of 10% could still be effectively separated yielding carbon-enriched and ash-enriched products with a LOI of 37.17% and 12.47%, respectively. Remarkably, the carbon recovery rate reaches a high of 78.44%. To a certain extent, the drying energy consumption is reduced. This paper provides significant inspiration for resource utilization of coal gasification fine ash.

Enhanced Charge Separation in Nanoporous BiVO4 by External Electron Transport Layer Boosts Solar Water Splitting.

The optimization of charge transport with electron-hole separation directed toward specific redox reactions is a crucial mission for artificial photosynthesis. Bismuth vanadate (BiVO4 , BVO) is a popular photoanode material for solar water splitting, but it faces tricky challenges in poor charge separation due to its modest charge transport properties. Here, a concept of the external electron transport layer (ETL) is first proposed and demonstrated its effectiveness in suppressing the charge recombination both in bulk and at surface. Specifically, a conformal carbon capsulation applied on BVO enables a remarkable increase in the charge separation efficiency, thanks to its critical roles in passivating surface charge-trapping sites and building external conductance channels. Through decorated with an oxygen evolution catalyst to accelerate surface charge transfer, the carbon-encased BVO (BVO@C) photoanode manifests durable water splitting over 120h with a high current density of 5.9mAcm-2 at 1.23V versus the reversible hydrogen electrode (RHE) under 1sun irradiation (100mWcm-2 , AM 1.5G), which is an activity-stability trade-off record for single BVO light absorber. This work opens up a new avenue to steer charge separation via external ETL for solar fuel conversion.