The development of efficient and stable visible-light-driven Z-scheme systems for overall water splitting was crucial for solar hydrogen production. However, performance was often limited by photocorrosion of sulfide-based hydrogen evolution photocatalysts and competing, deactivating side reactions involving the redox shuttle. Herein, we construct a robust Z-scheme system by employing a CoP-modified Ni-doped Zn0.5Cd0.5S heterojunction with strong interfacial interaction as the HEP, coupled with BiVO4 as the oxygen evolution photocatalyst. The optimized system exhibited an apparent quantum yield of 4.06% at 420 nm and enabled sustained co-evolution of hydrogen and oxygen at a near-stoichiometric ratio. It also demonstrated outstanding cycling stability. Crucially, it had been demonstrated that the regulation of the internal polarizability of HEP effectively suppressed the competitive reduction of the redox medium and the formation of passivated Prussian blue derivatives on the catalyst surface. This work provides fundamental insights into mitigating the side effects caused by fusion through polarizability regulation.

Solid solution strategy could improve the photocatalytic performance thermodynamically, yet the study focusing on the carrier dynamics of the solid solution catalysts was equally important. Herein, a series of ZnxCd1-xS solid solutions were successfully synthesized based on band structure regulation, and the carrier dynamics were investigated by femtosecond transient absorption spectroscopy (TAS) and DFT, which unveiled a variation of the mixed direct-to-indirect bandgap transition mechanism in ZnxCd1-xS solid solution. The indirect bandgap exhibited a lower photocarrier recombination rate and, more importantly, could also serve as a trapping center for photocarrier, thus promoting the efficiency of charge separation. Consequently, ZnxCd1-xS solid solutions achieved an approximately eleven-fold enhancement in the hydrogen evolution rate (1426.66 mu mol h(-1)) relative to that of bare CdS (129.83 mu mol h(-1)) under visible light (>420 nm). This work proposed that the enhanced photocatalytic performance could originate from both thermodynamic and kinetic aspects simultaneously, and that the alteration of the photocarrier transition mechanism is one of the main factors affecting the kinetics.

The study focuses on improving the removal efficiency of submicron particles using negative air ions (NAIs), which are challenging to remove. To enhance this efficiency, cascaded carbon fiber tubular (CFT) chargers were designed to boost particle charging. Through experiments and numerical simulations, the chargers' enhancement mechanisms, cooperation effects, and overall performance were evaluated. The optimal configuration for the CFT charger was identified as a gap distance (d =2.0 r(0))and grounded electrode length (L0/ =4 pi r(0)/3)that ensures high collection efficiency (96.7 % for 0.5 mu m particles at 4 m/s) and ultra-low ozone generation (7.25 ppb). The study found that while the average electric field strength (E) and ion density significantly influence charging, an un-usual improvement in collection efficiency was observed the charger with d =2.0 r(0) at u =3 m/s, likely due to the potential predominance of the maximum electric field strength (Emax) at relative higher velocity. Besides, the CFT charger demonstrated balanced performance compared to other reported works, although higher relative humidity (80 +/- 5 % RH) inhibits removal efficiency, which can be mitigated by reducing gas velocity.

One-step excitation photocatalytic overall water splitting (OWS) is an important reaction for clean energy conversion, but the efficiency is limited by the severe bulk-phase photocarrier recombination. To address this challenge, aluminum loaded tetragonal zircon BiVO4-based solid solution, Bi0.5Y0.5VO4, materials (xat%Al-BYV) were successfully prepared in this study. Photocatalytic experiments showed that the optimized xat%Al-BYV exhibited a 11-fold enhancement in OWS performance compared to the pristine BYV. Structural characterizations confirmed that Al existed in the form of gamma-Al2O3 and induced distortions of the VO4 microstructure in the xat%AlBYV via AlO4, which enhanced the material polarization that facilitated the separation of bulk-phase photocarrier. Photoelectrochemical tests and transient absorption spectroscopy (TAS) confirmed the optimized carrier dynamics, and TAS further elucidated the mechanism by which interfacial gamma-Al2O3 extracted photogenerated holes to inhibit photocarrier recombination. This work revealed the mechanism of Al loading to optimized BYV bulk-phase carrier dynamics via the synergistic effect of microstructure distortion-carrier extraction, and provided an insight for the design of other one-step excitation semiconductor materials in the future.

Photocatalytic hydrogen evolution, a promising clean energy conversion technology, faces efficiency limitations due to the mismatched timescales between sub-picosecond bulk photocarrier recombination and microsecond-scale surface reaction. Herein, a dual-strategy involving selenium decoration and NiSx cocatalyst loading was proposed to ameliorate the carrier dynamics bottleneck in CdS-based photocatalysts. The in situ loading of NiSx cocatalysts established an interfacial built-in electric field (BIEF) that enabled spatially oriented carrier separation and transfer, while the selenium modification optimized the light absorption range and Fermi energy level, obtaining an increase in the photocarrier concentration and further modulated the BIEF. Femtosecond transient absorption spectroscopy revealed a dual-channel carrier dynamics enhancement mechanism that BIEF-driven directional charge migration synergistically coupled with NiSx-mediated holes trapping. This synergistic effect achieved an approximately tenfold enhancement of hydrogen evolution rate (461.71 μmol h−1) relative to that of bare CdS under visible light (> 420 nm). This study elucidated the regulatory mechanism of element decoration and cocatalyst loading on carrier dynamics, providing an insight for designing high-performance photocatalysts.

The transmission of pathogenic airborne microorganisms significantly impacts public health and societal functioning. Ensuring healthy indoor air quality in public spaces is critical. Among various air purification technologies, electrostatic precipitation and atmospheric pressure nonthermal plasma are notable for their broad-spectrum effectiveness, high efficiency, cost-effectiveness, and safety. This review investigates the primary mechanisms by which these electrostatic methods collect and disinfect pathogenic aerosols. It also delves into recent advancements in enhancing their physical and chemical mechanisms for improve efficiency. Simultaneously, a thorough summary of mathematical models related to the migration and deactivation of pathogenic aerosols in electrostatic purifiers is provided. It will help us to understand the behavior of aerosols in purification systems. Additionally, the review discusses the current research on creating a comprehensive health protection system and addresses the challenges of balancing byproduct control with efficiency. The aim is to establish a foundation for future research and development in electrostatic aerosol purification and develop integrated air purification technologies that are both efficient and safe.

The research developed a new mechanism for particle agglomeration growth and fracture in the flow-electric coupling field. Microscopic visualization experiments reveal an optimum voltage range for controlling agglomerate growth dynamics. Additionally, we observed, for the first time, twisting behaviors of particle agglomerates during the growth and fracture process under the influence of the flow-electric field. A correlation between twist and fracture, varying with the increase in applied voltage, was identified. Moreover, we identified two distinct agglomeration modes: dendritic and chain agglomerates, each exhibiting unique growth characteristics. We discovered that the growth, twisting, and fracture of inclined dendritic agglomerates are influenced by two components of the electric dipole moment: the axial (Pg) and radial (Pt) components, with the aid of numerical simulation. Chain-like agglomerates exhibit growth followed by fracture. Our findings offer insights into the controlled growth of submicron particle agglomerates in gas phases using electric fields.

Inhalable particle is a harmful air pollutant that causes a significant threat to people's health and ecological environments, which should be removed to purify air, but there exists limited removal efficiency due to particle re-entrainment. Here, Operando observation system based on microscopic visualization method is developed to make in situ test of particle migration, deposition and re-entrainment characteristics on a lab-on-a-chip to achieve the investigation in micro-level scale. The deposition evolution of charged particles is recorded in electric field region intuitively, which confirms the fracture of particle chain occurs during the growth process of deposited particles. It captures the instantaneous process that a larger particle with micron size due to the coagulation of submicron particles fractures from main body of the particle chain for the first time. The analysis of migration behavior of a single submicron particle near electrode surface demonstrates the direct influence of drag force on the fracture of particle chain. This work is the first-time visualization of dynamic process and mechanism elucidation of particle re-entrainment at the micron level, and the findings will provide the theory support for the particle re-entrainment mechanism and bring inspires of enhancing capture efficiency of inhalable particle.

The gradient-doping technique has been widely applied to induce an oriented built-in electric-field. However, it is still not efficient enough for charge mobility especially for particulate semiconductors, as the field is primarily in one direction from inner to surface. Here, we propose a multilocal gradient-doping technique that a nanocapsule is designed to store dopants and then release them into semiconductors nonuniformly. As an illustration, scattered pyrochlore-type K2Ta2O6 nanoparticles have been validated the capability of storing and releasing K+, which subsequently diffuse into the substrate PCN. Multi point-radiative gradient in K+ concentration, confined within the K2Ta2O6's vicinity, will construct several 3D potential wells which can not only accelerate the carrier separation but also offer more migration channels for both photo-induced electrons and holes to the surface. Consequently, the multilocal K+ gradient-doping PCN shows the longest carriers' lifetime and highest AQY (similar to 21.8% at 400 nm) compared with the other uniformly doping techniques.

In this paper, six kinds of two-stage ESPs with various ratios of charger and collector units are designed to research the capture enhancement mechanism of submicron particles. The working conditions are optimized by studying the influence of gas velocity, charger current, and electric field strength of collector. Results show that the electrostatic field characteristics of the two-stage ESP with Ra = 1/6 is beneficial to improve the collection efficiency while slightly less stable. The indicator factor of particle charging enhancement effect of two-stage ESP with Ra = 6/1 fluctuates between 0.06 and 0.1, which suggests that the two-stage ESP with a higher proportion of charger units cannot achieve the satisfying performance for the limitation of ionic wind effect. Under comprehensive consideration of ionic wind effect and ozone emission, the two-stage ESP with Ra = 2/5 is selected at the first priority by exerting the advantages of fully particle charging and enough collection space, which has a strong potential in both particle charging enhancement and electric field enhancement. However, for improving the collection efficiency of submicron particle with a size ranging from 0.2 to 0.5 mu m which suffers from both of weak particle charging and agglomeration effect, the two-stage ESP with Ra = 4/3 is not recommended.(c) 2022 Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.

Plasma-coupled catalysis is a promising volatile organic compounds(VOCs)removal technology because of its interactional principles of plasma decomposition and catalytic oxidation.However,the problem of harmful by-products is still in trouble.A series of rare earth doped RE-NiOx(RE=Ce,Y,La)composite oxides were synthesized by metal organic frameworks(MOFs)-derived method for coupled plasma oxidation of benzene and by-product ozone removal.Compared with plasma alone,the 1％La-NiOx catalyst shows the best enhancement of 50％for benzene conversion with complete removal of a maximum of 800 ppm ozone.The energy consumption for 90％benzene removal efficiency(η90％)is also reduced from 3600 to 1200 J/L.Characterization results of RE-NiOx catalysts indicate that the doping of La causes interaction and synergistic effect between La and Ni,and the surface oxygen and lattice oxygen with defects play crucial roles in benzene oxidation and ozone decomposition,respectively.In addition,the decomposition mechanism of benzene and ozone under plasma is proposed.Plasma is responsible for the indiscriminate bond breaking in benzene and oxygen to form a variety of organic intermediates and ozone,while the La-NiOx catalyst selectively oxidizes the intermediates to COx/H2O and decomposes the ozone into oxygen.

While catalyst morphology plays an essential role in traditional thermal catalysis, the specific effects in plasma catalysis deserve further in-depth study. In the present study, hollow NiO nanospheres with a rambutan-like structure were successfully prepared by MOFs-derived method involving morphology modulation, and employed for the in-plasma catalytic oxidation of benzene. The results show an enhancement of 60 % for benzene removal, while CO2 selectivity was increased by 20 %. The energy consumption for 95 % benzene removal ef-ficiency (RE95%) was also reduced from 3600 J/L to 1100 J/L. Specifically, the hollow spherical shell structure is more abundant in surface oxygen species, including chemisorbed oxygen and surface lattice oxygen, which can be activated by plasma; the hollow structure also modulates the plasma discharge by shielding effect. The plasma field in turn also excites the oxidation activity of NiO, thus achieving the synergistic effect. In addition, a more comprehensive benzene decomposition pathway is proposed by analysis of the gaseous and non-gaseous in-termediates (tar), where the plasma non-selectively breaks the chemical bonds of reactants and the catalyst selectively oxidizes the organic intermediates to CO2, and they promote each other to achieve synergistic effects.

In this paper, aiming at PM 1, namely submicron particles which are the most difficult to remove in traditional purification technologies, it tries to improve their removal efficiency depending on collision enhancement and agglomeration effect. The effect of electric field and plate structure on collision enhancement is studied. Besides, a novel structure of corrugated plate is put forward and its removal performance is compared with parallel plate. Results show that it confirms the key function of the external electric field on the enhancement of particle collision through the trajectory visualization of particle streams with different polarity charging types. The intense turbulence quickens the particle collision and agglomeration in corrugated plate, and the enhancement of electric field around the bend can bring a quick capture firstly, and then the nonuniformity of electric field also leads to the positive effect of particle collision. Corrugated plate can achieve a 12% improvement of removal efficiency for PM 1 compared with traditional parallel plate, under consideration of collision enhancement brought by the airflow arrangement and agglomeration effect under Coulomb force between positive and negative particles.

For the low concentration and intractable VOCs and CO2, plasma-coupled catalysis has superior advantages and development potential to deal with them. However, there are critical issues such as efficiency to be further improved and unclear coupling mechanism to reveal. In this review, various types of catalysts are categorized and evaluated by exploring their enhancement effect in plasma-catalytic system to indicate their synergistic excellence and application limitation. Besides, the detailed research of synergistic mechanism between plasma and catalysis is given more attention, which is rapidly progressing due to the development of in-situ experimental techniques and kinetic analysis approach. In our view, the future direction of plasma catalysis is to reveal the synergistic mechanism more deeply for efficiency improvement with efficient catalysts, and pave the way for practical application.

In this work, a spike-tubular electrostatic device was developed for effectively removing particulate matter (PM) and VOCs, based on multi-stage electric field enhancement and expanded arc interface ratio of corona discharge. In the experiment, it was equipped with a portable 12 V D.C. power supply module and a fan module; PM from moxa smoke, mainly composed of submicron particles with a high penetrate rate, and HCHO were employed to test its electrostatic precipitation and oxidation ability, respectively. Additionally, CFD numerical simulation was adopted to investigate the characteristics of the electric field, the flow field, and the ozone generation. Experi-mental results showed that the electrostatic device could remove 99% of the fine particles at 2 m/s. Meanwhile, it could also remove HCHO of 2.14 x 103-1.07 x 104 mu g/m(3) concentration with 100% efficiency. By comparison, its oxidation capacity could be about 80 times that of ozone oxidation, revealing the enhanced oxidation ability of other short-living reactive species. Simulation results proved that the promising purification performance resulted from the locally enhanced electric field strength, up to 2 x 10(7) V/m in the central region, and sufficient contact between pollutants and the corona discharge region. Finally, as verified by the airtight chamber cycle experiment and case comparison, the device owns feasible purification ability and promising energy yield (0.79 g/kWh) in the application. Moreover, prospects and strategies for the device's practical application in air pu-rification and disinfection were proposed, which may provide helpful enlightenment for air purification.

In this work, a laboratory-scale charger, with a single wire electrode of one charging unit for effective ozone control, and collector with a 300 mm length and 5 mm plate-plate distance extremely short for high-efficient capture of noxious particles, was designed and assembled as a two-stage ESP to study the effect of collection length for removal of PM2.5, in particular to these sub-micron particles which had the highest penetration rate during the electrostatic capture process. The influence factors, including the current density of charger, the electric field strength of collector, and gas velocity, were investigated in detail. Multiple channels of the collector were chosen to thoroughly compare the performance difference by detecting the particle concentration in the electric field directly. Besides, the ozone concentration test was carried out in various parameters to explore the influence degree simultaneously. Experimental results showed that the collection efficiency based on the number concentration could reach up to be 92.9%, 96.7%, and 97.7% for 0.25 mu m, 0.35 mu m, and 0.45 mu m diameter particles at 4 m/s gas velocity, respectively, which benefited from the advantages of long collection plate and short migration distance. Compared with the influence factors of charger current density and gas velocity, electric field strength occupied the middle position in effecting the collection efficiency, whose most massive index factor was about 18 at a collection length of 30 cm. While the maximum index factor of current density was 3.7 at a collection length of 15 cm and of gas velocity was 27.5 at a collection length of 10 cm. The ozone concentration test suggested that charger current, gas velocity, collection length, and electric field strength could affect the ozone concentration from strong to weak in sequence.

The high-voltage electric field can effectively capture charged aerosols and has the effect of killing microbial aerosols simultaneously. In this article, an innovative visualization method for investigating the dynamic characteristic of submicron-scale aerosol particles in the high-voltage electric field is developed. Based on reasonable working principles and reliable experimental schemes, the movement of submicron-scale aerosol particles is observed and visualization images in different working conditions are photographed. Besides, with the aid of numerical method and solution of related equations, simulation researches on flow field distribution, electrostatic field characteristics, particle charging and motion behavior characteristics are also carried out. Visualization results prove the linear motion law of aerosol particles in an electric field of 0-3 kV/cm unit. As for 1 µm diameter particle, its migration velocity in 1 kV/cm electric field is measured as 0.016 m/s and 0.019 m/s after positive and negative charging of 1.5 kV voltage, respectively. A reliable calculation formula (η=(VjqpLj)/(3πμD2uxdp)) for predicting collection efficiency is derived and established based on actual particle migration velocity. The researches on the migration and capture law of submicron-scale aerosol in the high voltage electric field gives a key reference for the development and design of efficient removal of microbial aerosol and air purification equipment.

In this work, an integrated two-stage electrostatic precipitator (ESP) is developed to efficiently remove PM2.5 based on actual demand for air purification. It includes a power supply module, a charging module, a collection module, and a fan module. In the application test, the typical PM2.5, from the indoor combustion of mosquito coil, was selected as the removal target. At the same time, influence factors related to the developed prototype in the application which includes collector channel, gas velocity, Z-direction position, and collector electric field were investigated systematically with the CFD numerical simulation method. Notably, the collection efficiency of the two-stage ESP prototype for PM2.5 can be up to more than 99% at 3 m/s gas velocity, even in 4 m/s gas velocity, it can also reach more than 98%, which proved the application feasibility of the device. Moreover, the issue of the collector's efficiency limitation is also analyzed in-depth, which provides guidance and suggestions for the secondary entrainment suppression and application strategies in different places after compared with the air quality guidelines (AQG).

In this paper, a novel approach based on the Lagrangian particle tracking method which adopted the accumulated displacement of particles as judgment standard was proposed to investigate the particle collision mechanism under the influence of non-contact external forces in a typical wire-plate electrostatic precipitator. The accumulated displacement of different diameter particles could reflect the range of particle motion and the collision probability inside the ESP, which was obtained from the calculated trajectory coordinates of particles under the influence of Brownian force and electric force. Results showed that the electric force controlled the particle?s trajectory direction while the Brownian force only made particles fluctuate along with the main track. The binary collision models with the determination of the dominant force were developed, which can be divided into two areas respectively called the electric force dominant region and the Brownian force dominant region. The total accumulated displacement of the submicron particle presented a U-shape curve, which matched well with the grade collection efficiency of fine particles in various experiments and demonstrated the validity of the proposed method. Also, the approach had good expansibility in investigating the role of other external forces in particle collision and could provide references for the design and working condition selection of ESP. ? 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. In this paper, a novel approach based on the Lagrangian particle tracking method which adopted the accumulated displacement of particles as judgment standard was proposed to investigate the particle collision mechanism under the influence of non-contact external forces in a typical wire-plate electrostatic precipitator. The accumulated displacement of different diameter particles could reflect the range of particle motion and the collision probability inside the ESP, which was obtained from the calculated trajectory coordinates of particles under the influence of Brownian force and electric force. Results showed that the electric force controlled the particle?s trajectory direction while the Brownian force only made particles fluctuate along with the main track. The binary collision models with the determination of the dominant force were developed, which can be divided into two areas respectively called the electric force dominant region and the Brownian force dominant region. The total accumulated displacement of the submicron particle presented a U-shape curve, which matched well with the grade collection efficiency of fine particles in various experiments and demonstrated the validity of the proposed method. Also, the approach had good expansibility in investigating the role of other external forces in particle collision and could provide references for the design and working condition selection of ESP.

This paper develops a novel approach for evaluating charged particles' collision probability in the external electric field of a regular two-stage electrostatic precipitator based on Lagrangian particle tracking method, which overcomes itself difficulties and that of the Eulerian method. The numerical simulation aims to obtain the particles' accumulated displacement which is a parameter to reflect the efficiency of particle collision. The effect factors of frequency, gas velocity, plate spacing and applied voltage are also considered. Results indicate that the external electric field of R-AC is more beneficial to particle collision compared to the other waveforms of AC. Besides, frequency and plate spacing are not found to have obvious or regular effect on collision probability, but the promotion effect of applied voltage on it was obtained. The dimensionless coefficient analysis provides extremely useful information for the optimization of working conditions in different types of the external electric field.