Enhanced Separation Efficiency Research Articles

Impact of acid surface pretreatment on the hydrophobic agglomeration of micro-fine ilmenite and titanaugite in flotation

Acid surface pretreatment was employed to realize the selective hydrophobic agglomeration of micro-fine ilmenite in flotation. Microflotation and artificially mixed mineral experiments manifested that after acid surface pretreatment, the recovery of micro-fine ilmenite with the increase of NaOL concentration and the floatability difference of micro-fine ilmenite and titanaugite increased significantly. Zeta potential and contact angle analyses suggested that acid surface pretreatment intensified the adsorption of NaOL on ilmenite surfaces while reducing it on titanaugite surfaces. Turbidity, optical microscope, and EDLVO theory analyses attested that the hydrophobic attraction dominated in a short particle spacing in NaOL solution. Following acid surface pretreatment, the hydrophobic agglomeration between micro-fine ilmenite particles enhanced in NaOL solution due to increased hydrophobic attraction. In contrast, the hydrophobic attraction and agglomeration between micro-fine titanaugite particles as well as between micro-fine ilmenite and titanaugite particles weakened. Overall, acid surface pretreatment improved the selective adsorption of NaOL and the selective hydrophobic agglomeration of micro-fine ilmenite, resulting in enhanced separation efficiency and recovery of micro-fine ilmenite.

Computational Analysis of Permeance Prediction for Gas Separation Membrane Using Countercurrent Flow Model

Gas separation polymeric membranes have gained significant attention in various industries, including gas processing, petrochemicals, and environmental applications. Accurately predicting the permeance of these membranes is crucial for optimizing their design and performance. This paper presented a numerical prediction model for the permeance of a binary gas mixture under various process conditions, using only algebraic equations to minimize the calculation effort. The model considers input parameters such as feed and permeate flow rates, feed pressure, feed and permeate mole fraction, and membrane area. It demonstrates the behavior of permeance and selectivity in this study. The study also presented two case studies that utilize predicted selectivity to model counter-current flow and compare the results with experimental data from the literature. The first case study involves recovering helium from natural gas using an asymmetric high-flux membrane. The second case study separates air using nano-porous carbon as the membrane material. The numerical analysis successfully accurately predicted the permeance of gas separation polymeric membranes. The model accounted for variations in membrane thickness, feed composition, and operating conditions, providing valuable insights into the overall performance of the membrane system. It also allowed for the optimization of membrane design and operational parameters to enhance separation efficiency and productivity. The study showcased the effectiveness of numerical techniques in accurately predicting membrane performance. The developed model can be a valuable tool for membrane designers and engineers, enabling them to optimize the design and operation of gas separation systems.

CFD-based shape optimization of structured packings for enhancing separation efficiency in distillation

Free-form shape optimization techniques are investigated to improve the separation efficiency of structured packings in laboratory-scale distillation columns. A simplified simulation model based on computational fluid dynamics (CFD) for the mass transfer in the distillation column is used and a corresponding shape optimization problem is formulated. The goal of the optimization is to increase the mass transfer in the column by changing the packing's shape, which has been previously used as criterion for increasing the separation efficiency of the column. The computational shape optimization yields promising results, with an increased mass transfer of nearly 20%. For validation, the resulting optimized shape is additively manufactured using 3D-printing and investigated experimentally. The experimental results are in good agreement with the performance improvement predicted by the computational model, yielding an increase in separation efficiency of around 20%.

Unlocking optimal performance and flow level control of three-phase separator based on reinforcement learning: A case study in Basra refinery

This research explores the application of a new reinforcement learning (RL-based) controller for a three-phase separator connected to a gas turbine. The control of flow levels within the separator directly impacts fluid flow turbulence, especially when the equipment is linked to waste heat gas from the turbine to improve gas quality. The study introduces the novel RL-based controller and validates its effectiveness in real-world conditions using three-phase separators in Basra, Iraq, and through a review of relevant literature. The controller can adapt to inlet conditions such as pressure, temperature, mass flow rate, and incoming heat from the gas turbine. Waste heat recovery from the gas can enhance gas purity but also increase turbulence in water and oil. Maintaining a calm flow while ensuring high-speed flow over the baffle in the middle of the separator is crucial for optimal performance. The study considers two geometrical configurations of the vessel for redesigning the separator at the Basra refinery. The controller was implemented using the groovyBC utility within the OpenFOAM software. This model was then utilized to simulate real-world scenarios at the Basra refinery, displaying faster convergence, more rapid response, and more accurate tracking of the target fluid level. This study marks the initial effort to apply the deep deterministic policy gradient (DDPG) controller in computational fluid dynamic (CFD) work. The findings demonstrated a significant enhancement in separation efficiency by more than 36%, as well as smoother streamlines through the control and maintenance of pressure and velocity over the baffle.

Exploring the utility of complementary separations in liquid chromatography

An alternative strategy is explored for the separation of samples by liquid chromatography (LC). Unlike traditional approaches that aim to resolve all components in a given sample within a single LC separation, the proposed strategy uses two or more distinct separations carried out with a different gradient program and/or using different separation chemistries i.e., a different set of mobile and stationary phase. This set of complementary incomplete separations (CIS) is selected such that each component is at least fully resolved once, meaning the most critical pairs of each individual separation can be left unseparated. This allows for a significant time saving per separation. To investigate whether such an approach can lead to overall shorter analysis times than is possible with the fastest single-run gradient separation, a comprehensive in-silico study covering a statistically significant number of samples is undertaken. The investigation shows that, for the presently considered sample sets and chemistries, CIS has a substantially higher probability, about two times greater for the simplest samples considered in this work and as much as 30 times greater for more complex samples, to fully resolve an unknown sample compared to a single gradient separation. Comparing separation speeds, the CIS approach can achieve complete sample resolution on average approximately four times faster than a single separation. Our findings thus demonstrate the potential of CIS in enhancing separation efficiency and offer insights regarding their use for solving analytical challenges.

S-scheme 2D/2D B-doped N-deficient g-C3N4/ZnIn2S4 heterojunction for efficient H2 production intergrated with tertracycline degradation under visible-light illumination

A novel S-scheme 2D/2D boron-doped nitrogen-deficient g-C3N4/ZnIn2S4 (BDCNN/ZnIn2S4) heterojunction was successfully fabricated via the in-situ assembly of ZnIn2S4 onto BDCNN in an oil bath. To assess the quality and characteristics of the synthesized photocatalysts, a comprehensive range of characterizations were conducted. The innovative S-scheme 2D/2D BDCNN/ZnIn2S4 heterojunction, equipped with a deliberately established inter-built electric field, facilitates rapid electron transfer and enhanced separation efficiency of photo-induced carriers. Consequently, this heterojunction demonstrates remarkable enhancements in both H2 production and TC degradation under visible-light illumination (λ > 420 nm). The optimized BDCNN/ZnIn2S4 heterojunction exhibited impressive photocatalytic performance, achieving a promising H2 evolution rate of 2378.8 μmolg−1h−1 and a high degradation efficiency exceeding 90 % (k = 0.021 min−1) for TC. This noteworthy improvement in photocatalytic performance is primarily attributed to the synergistic effects of boron-doping and nitrogen-defects within BDCNN, coupled with the unique S-scheme photocatalytic mechanism inherent to the BDCNN/ZnIn2S4 heterojunction. Overall, this study introduces a groundbreaking approach for constructing 2D/2D g-C3N4-based heterojunctions that exhibit exceptional visible-light photocatalytic capabilities, thereby offering significant potential for various photocatalytic applications.

Analysis of cyclone separator solutions depending on spray ejector condenser conditions

The core design strategy for minimizing CO2 emissions in gas power plant entails combining a spray ejector condenser (SEC) and separator to accomplish steam condensation and CO2 purification. This innovative process involves direct-contact condensation of steam with CO2, facilitated by interaction with a subcooled water spray, along with a cyclone separator mechanism intended for generating pure CO2. The investigation of the SEC section, both experimentally and analytically, provides crucial insights into its operational dynamics. Given the susceptibility of cyclone efficiency to fluctuations in SEC conditions, this research endeavors to examine the impacts of CO2 volumetric flow rate and droplet break-up within the SEC on the separation efficacy of the cyclone separator. Additionally, the impact of cone size on the performance of the cyclone has been investigated. Here, a three-dimensional, transient, and turbulent cyclone separator is numerically simulated using Ansys Fluent 2021 R1. The Reynolds Stress Model is employed to simulate turbulent flow, while a mixture model is utilized to replicate swirl two-phase flow within the separators. The findings revealed that reductions in steam and CO2 flow rates were associated with a decrease in outlet temperature but an increase in SEC inlet temperature, leading to a rise in temperature difference and heat transfer rate. Furthermore, an augmentation in cyclone cone size (from 0.2 to 0.5 m) resulted in enhanced separation efficiency (from 77.30 % to 80.98 %) alongside an elevation in pressure drop (from 6.08 Pa to 10.91 Pa), suggesting a compromise between CO2 purification and energy consumption. Additionally, elevated CO2 flow rates induced a rise in pressure drop and separation efficiency, ultimately achieving maximum efficiency at a rate of 24 gs. Moreover, the exploration into droplet breakup manifesting in a boost in separation efficiency from 50.98 % to 100 % across droplet diameters ranging from 1 to 20 μm.

Strongly tribocatalytic dye degradation of high-entropy powder through harvesting friction

The omnipresent friction can be harvested to generate electricity, thereby facilitating redox reactions to degrade dye wastewater, which can be named as tribocatalysis. Here, it’s experimentally found that the high-entropy CoCrFeMnNi powder synthesized via the Vacuum Induction Gas Atomization (VIGA) technique, can behave the obvious tribocatalytic Rhodamine B (RhB) dye degradation performance. In the tribocatalysis dye degradation process, friction occurs at the interface between the catalyst’s surface and the stirring Teflon rod. The tribocatalytic RhB dye degradation ratios of the high-entropy CoCrFeMnNi powder catalysts at stirring speeds of 200 rpm, 400 rpm, 800 rpm, 1000 rpm, and 1200 rpm are 14.7 %, 70.3 %, 93.2 %, 99.4 %, and 99.8 %, respectively. It’s also found that the RhB dye degradation ratio can be slightly enhanced under an external DC magnetic field provided by a commercial NdFeB magnet, which may be attributed to the magnetically-induced enhancement of separation efficiency of these positive and negative carriers. After being recycled for 3 times, the CoCrFeMnNi powder can still degrade 90.8 % RhB dye. The CoCrFeMnNi powder with the excellent tribocatalytic activity is potential for application in dye wastewater treatment through utilizing the friction energy in the environment.

A stepwise multi-stage continuous dielectrophoresis separation microfluidic chip with microfilter structures

The separation of target microparticles using microfluidic systems owns extensive applications in biomedical, chemical, and materials science fields. Integration of microfluidic sorting systems employing dielectrophoresis (DEP) technology has been widely investigated. However, enhancing separation efficiency, purity, stability, and integration remains a pressing issue. This study proposes a stepwise multi-stage continuous DEP separation microfluidic chip with a microfilter structure. By leveraging a stepwise electrode configuration, a gradient electric field is generated to drive target microparticles along the electric field gradient, thereby enhancing separation efficiency. Innovative integration of a microfilter structure facilitates simultaneous filtration and improves flow field distribution, thus enhancing system stability. Through the synergistic effect of stepwise electrodes and the microfilter structure, superior coupling of electric and flow fields is achieved, consequently improving the sorting purity, separation efficiency, and system stability of the DEP-based microfluidic sorting system. Validation through simulation and separation of polystyrene microspheres demonstrates the excellent particle separation performance of the proposed system. It evidently shows potential for seamless extension to various biological microparticle sorting applications, harboring significant prospects in the biomedical domain field.

Optimizing CO2 Purification in a Negative CO2 Emission Power Plant

AbstractIn the pursuit of mitigating CO2 emissions, this study investigates the optimization of CO2 purification within a negative CO2 emission power plant using a spray ejector condenser (SEC) coupled with a separator. The approach involves direct‐contact condensation of vapor, primarily composed of an inert gas (CO2), facilitated by a subcooled liquid spray. A comprehensive analysis is presented, employing a numerical model to simulate a cyclone separator under various SEC outlet conditions. Methodologically, the simulation, conducted in Fluent, encompasses three‐dimensional, transient, and turbulent characteristics using the Reynolds stress model turbulent model and mixture model to replicate the turbulent two‐phase flow within a gas–liquid separator. Structural considerations are delved into, evaluating the efficacy of single‐ and dual‐inlet separators to enhance CO2 purification efficiency. The study reveals significant insights into the optimization process, highlighting a notable enhancement in separation efficiency within the dual‐inlet cyclone, compared to its single inlet counterpart. Specifically, a 90.7 % separation efficiency is observed in the former, characterized by symmetrical flow patterns devoid of wavering CO2 cores, whereas the latter exhibits less desirable velocity vectors. Furthermore, the investigation explores the influence of key parameters, such as liquid volume fraction (LVF) and water droplet diameter, on separation efficiency. It is ascertained that a 10 % LVF with a water droplet diameter of 10 µm yields the highest separation efficiency at 90.7 %, whereas a 20 % LVF with a water droplet diameter of 1 µm results in a reduced efficiency of 50.79 %. Moreover, the impact of structural modifications, such as the addition of vanes, on separation efficiency and pressure drop is explored. Remarkably, the incorporation of vanes leads to a 9.2 % improvement in separation efficiency and a 16.8 % reduction in pressure drop at a 10 % LVF. The findings underscore the significance of structural considerations and parameter optimization in advancing CO2 capture technologies, with implications for sustainable energy production and environmental conservation.

Pneumatic separation and process simulation of waste printed circuit boards pyrolysis residue

In this study, the application of Z-shape pneumatic separator for separating metal and nonmetal particles in pyrolysis residue of waste printed circuit boards was investigated, and the flow field characteristics and particle motion behavior in the separator were revealed through flow field simulation. The pneumatic separation results indicated that pre-screening significantly enhanced the separation efficiency of metals and nonmetals in pyrolysis residue. The simulation results showed that the large gradient of airflow velocity distribution and the turbulent flow field within the Z-shape separation cavity are beneficial for dispersing particles and reducing the influence between particles of different properties, thus enhancing separation efficiency. Using Rocky DEM for modeling of different shapes and properties of particles, and then combined with ANSYS Fluent can better simulate the particle separation behavior in the pneumatic separator.

Construction of Z-scheme BiOCl/Bi2WO6 heterojunctions with oxygen vacancies for effectively destruction of two typical contaminants

In this study, Z-scheme BiOCl/Bi2WO6 heterojunctions with enriched oxygen vacancies (OVs) were fabricated. Enhanced separation efficiency of photogenerated electron-hole pairs from BiOCl/Bi2WO6 composite was confirmed through surfacephotovoltagespectroscopy (SPS), photocurrent and electrochemical impedance spectroscopy (EIS) analysis. Photocatalytic decontamination of rhodamine B (RhB) and tetracycline (TC) over BiOCl/Bi2WO6 composite was investigated, and BiOCl/Bi2WO6 heterojunctions reveal higher photocatalytic performance than BiOCl and Bi2WO6. The boosted activity of BiOCl /Bi2WO6 heterojunctions stems from the improved separation rate of carriers. In view of electron paramagnetic resonance (EPR) results and band structures of BiOCl and Bi2WO6, photocatalytic mechanism of the BiOCl/Bi2WO6 heterojunctions follows Z-scheme mechanism.

Micro gas chromatography column using ionic liquid modified metal-organic framework as stationary phase for rapid breath analysis of gastric cancer

The micro gas chromatography columns (μGCs) were prepared for rapid breath analysis of gastric cancer. The synergistic effect of the specific surface area and the action of pore diameter on the separation capacity was investigated. The μGC-IL/UIO-66 was prepared using [P66614][Cl]/UIO-66 as the stationary phase. For comparison, the μGC-IL and the μGC-UIO-66 were prepared using [P66614][Cl] and UIO-66 as stationary phase, respectively. [P66614][Cl]/UIO-66 had a high specific surface area with a pore diameter distribution of 0.49 nm. The high specific surface area of [P66614][Cl]/UIO-66 improved the efficiency of adsorption and desorption, while the porous structure with an appropriate pore diameter acted as an efficient molecular sieve, synergistically enhancing separation efficiency. So compared to the μGC-IL and the μGC-UIO-66, the HETP of μGC-IL/UIO-66 was reduced by 68.2% and 22.6%, respectively. In the analysis of volatile biomarkers (acetone, benzene, n-hexane and toluene) for gastric cancer, the resolutions between adjacent peaks were 1.96, 2.13 and 3.67, which met the requirements for quantitative analysis (R > 1.5). The retention times of acetone, benzene, n-hexane and toluene were 0.72 min, 0.96 min, 1.33 min and 1.67 min, which enables rapid analysis. All may suggest that the μGC-IL/UIO-66 has a promising application in rapid breath analysis of gastric cancer.

Synthesis of NH2-UiO-66/Bi4O5I2 heterojunction for high tetracycline reduction under visible light

In this study, direct Z-scheme NH2-UiO-66/Bi4O5I2 heterostructures were successfully synthesized to harness visible light for the degradation of tetracycline (TC), thereby evaluating the photocatalytic activity of the materials. NH2-UiO-66/Bi4O5I2 demonstrated robust photocatalytic efficacy under visible light irradiation, with NU/BOI-80 exhibiting the highest TC removal rate (91 %) within 120 min. Through UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and Photoluminescence (PL) diagram analysis, it was found that NH2-UiO-66/Bi4O5I2 shows good photocatalytic properties. Mott-Schottky and electrochemical impedance spectroscopy (EIS) indicated the enhanced separation efficiency of electron-hole pairs within the material, thereby mitigating recombination losses. In addition, free radical capture experiments and the combination of electron spin resonance (ESR) showed that ·O2−and h+ were the main active species. At the same time, NH2-UiO-66/Bi4O5I2 has been confirmed to have good stability. Finally, a proposed photocatalytic electron transfer mechanism was formulated based on the characterization and experimental results. This study presents a promising avenue for leveraging metal-organic framework photocatalysts for the effective removal of TC.

Sono-photocatalytic degradation of Tetracycline and Ciprofloxacin antibiotics using microwave-reflux of NiO-MoS2/rGO ternary nanocomposite

In this study, NiO-MoS2/rGO nanocomposites were synthesized successfully by a simple microwave assisted refluxing method by varying the mass ratios of rGO. The NiMG-50 ternary nanocomposite has been applied by sonocatalytic, photocatalytic and sono-photocatalytic degradation for the removal of tetracycline (TTC) and ciprofloxacin (CIP) antibiotics. Physicochemical properties of the synthesized samples were characterized by Powder X-ray Diffraction (PXRD), Energy Dispersive X-ray Spectroscopy (EDAX) and X-ray Photoelectron Spectroscopy (XPS) corroborated the phase purity of NiMG-50 nanocomposite. The High Resolution Scanning Electron Microscopy (HR-SEM) image reveals the zigzag arrangements of NiO nanoflakes over MoS2 and rGO sheets. The tight contact of platelet shaped-NiO NP’s and curled layer-MoS2 on the sheets of rGO results in the separation of photo-induced e--h+ pairs as demonstrated by the High Resolution Transmission Electron Microscopy (HR-TEM) analysis. Optical properties reveal a reduced band gap and enhanced separation efficiency with fast charge transfer rate, improving the organic pollutant degradation efficiency. NiMG-50 demonstrated a good catalytic activity against TTC and CIP in sono-photocatalytic process with an efficiency of 94.10 % and 83.96 % at 35 and 90 min, respectively. Simultaneously, the experimental results showed that the NiMG-50 composite follows the pseudo-first order reaction kinetics with a rate constant (KSP) value of 0.077 min−1 and 0.015 min−1 for TTC and CIP. The radical trapping test and degradation mechanism indicated that the continuous contribution of ̇OH and ̇O2– reactive radicals are the major ones responsible for the active involvement in the degradation reaction. This research work gives a fresh prospects to the as prepared NiMG catalyst as an efficient composite with a good applicability for the sono-photocatalytic degradation of pharmaceutical products.

Facile synthesis of Bi3O(OH)(AsO4)2 and simultaneous photocatalytic oxidation and adsorption of Sb(III) from wastewater

Antimony (Sb) decontamination in water is necessary owing to the worsening pollution which seriously threatens human life safety. Designing bismuth-based photocatalysts with hydroxyls have attracted growing interest because of the broad bandgap and enhanced separation efficiency of photogenerated electron/hole pairs. Until now, the available photocatalysis information regarding bismuth-based photocatalysts with hydroxyls has remained scarce and the contemporary report has been largely limited to Bi3O(OH)(PO4)2 (BOHP). Herein, Bi3O(OH)(AsO4)2 (BOHAs), a novel ultraviolet photocatalyst, was fabricated via the co-precipitation method for the first time, and developed to simultaneous photocatalytic oxidation and adsorption of Sb(III). The rate constant of Sb(III) removal by the BOHAs was 32.4, 3.0, and 4.3 times higher than those of BiAsO4, BOHP, and TiO2, respectively, indicating that the introduction of hydroxyls could increase the removal of Sb(III). Additionally, the crucial operational parameters affecting the adsorption performance (catalyst dosage, concentration, pH, and common anions) were investigated. The BOHAs maintained 85% antimony decontamination of the initial yield after five successive cycles of photocatalysis. The Sb(III) removal involved photocatalytic oxidation of adsorbed Sb(III) and subsequent adsorption of the yielded Sb(V). With the acquired knowledge, we successfully applied the photocatalyst for antimony removal from industrial wastewater. In addition, BOHAs could also be powerful photocatalysts in the photodegradation of organic pollutants studies of which are ongoing. It reveals an effective strategy for synthesizing bismuth-based photocatalysts with hydroxyls and enhancing pollutants’ decontamination.

A readily synthesized ZnIn2S4/attapulgite as a high-performance photocatalyst for Cr(VI) reduction

Herein, a ZnIn2S4-decorated attapulgite photocatalyst (ZnIn2S4/ATP) was successfully synthesized by a facile oil bath heating method. It shows superior reduction efficiency for the removal of Cr(Ⅵ). The improved photocatalytic performance is primarily attributed to the intercalation effect of ZnIn2S4 and attapulgite (ATP), enhanced separation efficiency of photogenerated electron-hole pairs, and improved transport efficiency of photogenerated carriers. Moreover, insight into the photocatalytic mechanism demonstrates that •O2− and e− are the major active species in the photocatalytic reduction of Cr(VI) over ZnIn2S4/ATP. This work serves as a reference for integrating natural clay with semiconductors for photocatalytic wastewater treatment.

Numerical investigation on the effect of feed operating parameters and inlet structure on a cyclone utilizing flow splitting for performance enhancement

The shunting technique is regarded as one of the most crucial approaches for suppressing localized secondary flow within a cyclone. This study employs the Reynolds stress model and discrete phase model to investigate the impact of inlet structure and feed operating parameters on the performance of enhanced cyclone with split flow (ECSF), aiming to further enhance its efficiency. The findings demonstrate that the optimum feed velocity of ECSF is 29 m/s, which surpasses that of Lapple cyclone at 23 m/s. In addition, both a contracting inlet and multiple inlets contribute to enhancing the separation efficiency of ECSF. Specifically, ECSF with a contracting inlet exhibits a total separation efficiency of 86.8% for 2.5 μm particles, representing an improvement of 12.3% compared to ECSF with a straight inlet configuration. The enhancement in separation efficiency achieved through the implementation of the four-inlet design is even more pronounced. The segregated particles are directed into the discharge pipe via either underflow or bypass flow, and the trajectory of particle entry into the discharge pipe is closely associated with their cross-sectional positioning prior to entering the cylinder.

Optimized synthesis of Fe-doped Ohmic Schottky heterojunctions for efficient NO3− photocatalytic reduction to generate N2

Capacitive Fe-doped Ni2P(Fe2xNi2(1-x)P) is synthesized via the modified solvothermal method to form Ohmic Schottky heterojunctions with monolayer Ti3C2 (MLTC). The composite (10 % 0.1FNP/CdS-2 % MLTC) achieved a high hydrogen evolution rate (HER) of 19.18 mmol h−1 with a 50 mg sample. In a mere span of 3 h, an impressive NO3− reduction of 0.42 mg/L was achieved, accompanied by an exceptional 92 % N2 selectivity. Quantum efficiency (QE) can reach 56.22 % (λ = 475 nm) by adding 0.1FNP and MLTC. In contrast to previous catalysts, the QE of visible light after 500 nm has been improved to 45.2 % (λ = 500 nm) or 36.4 % (λ = 550 nm). The significant enhancement of HER and NO3− reduction is attributed to the enhanced adsorption of oxygen-containing reactants, the lowering of the reduction overpotential, further enhanced separation efficiency of photogenerated carriers through the ohmic Schottky heterojunction after iron doping. Additionally, the observed capacitor-like nature of 0.1FNP is also an essential factor for the enhanced reduction ability of the composites.

Influence of substrate temperature on the structural, morphological, and photoelectric properties of Bi2WO6 thin films deposited by magnetron sputtering

The effect of substrate temperature (Ts) increasing from RT (room temperature) to 600 °C on the structural, morphological, optical and photoelectrochemical properties of BixWO6 (1.98≤x ≤ 2.84) thin films deposited by RF magnetron sputtering has been investigated by various techniques including XRD, EDS, SEM, AFM, XPS, UV–vis DRS, PL and EIS. AFM and EDS show that as Ts increases, the Bi/W atomic ratio gradually decreases; the amorphous BixWO6 thin films grown under 300 °C had a very smooth surface with an RRMS value in the range of 0.5–0.8 nm. However, as the substrate temperature increases from 400 to 600 °C, for the crystalline BiWO6 thin films the RRMS value increases to a range of 18.3–30.5 nm and there is a transition of the crystalline orientation from {131} to {200} as confirmed by XRD. The films grown at Ts = 600 °C exhibit some favorable properties such as a Bi/W ratio close to 2:1, lattice expansion relaxation, low Eg and excellent photoelectric reproducibility which is about 3–29 times higher than that of other films grown at low Ts (300–500 °C). PL and EIS analysis as well as photoelectrochemical test results demonstrated the enhanced separation efficiency of photogenerated electron-hole pairs and charge transfer for the stoichiometric and well-crystallized BixWO6 thin films, showing their good potential for practical applications such as visible light responsive photocatalyst or photoelectrode.