Potential Drop Research Articles

Development of Semi-Empirical and Machine Learning Models for Photoelectrochemical Cells

We introduce a theoretical model for the photocurrent-voltage (I-V) characteristics designed to elucidate the interfacial phenomena in photoelectrochemical cells (PECs). This model investigates the sources of voltage losses and the distribution of photocurrent across the semiconductor–electrolyte interface (SEI). It calculates the whole exchange current parameter to derive cell polarization data at the SEI and visualizes the potential drop across n-type cells. The I-V model’s simulation outcomes are utilized to distinguish between the impacts of bulk recombination and space charge region (SCR) recombination within semiconductor cells. Furthermore, we develop an advanced deep neural network model to analyze the electron–hole transfer dynamics using the I-V characteristic curve. The model’s robustness is evaluated and validated with real-time experimental data, demonstrating a high degree of concordance with observed results.

Drainage gradient versus seasonal cycles: Differential response of microbial community composition to variations in soil moisture

AbstractThe variation in the soil microbial community composition over time was assessed at monthly time steps for 1 year in three neighboring Mollisols spanning a drainage gradient. This was done to distinguish between natural oscillations in the community composition versus lasting adaptations to environmental factors such as soil water availability. To isolate soil water availability as a controlling factor, we selected three soils sharing the same soil order (fine‐silty, superactive Argixerolls/Argialbolls); slope (0%–1%); temperature regime (mesic); moisture regime (xeric); and land use history (continuous grassland for the past 10 years) but differing in drainage class (well‐drained vs. moderately well‐drained vs. poorly drained). Changes in microbial diversity were quantified by monitoring the bacterial community at monthly intervals for 1 year. Within individual soils, α‐diversity varied little with season and drainage classes. Despite the three soils experiencing the same climate regime and vegetation/land use, they exhibited distinct community composition and turnover, which we attribute to differences in moisture availability across drainage and seasons. We posit that a seasonal recurring drop in soil redox potential induced by seasonal water saturation in the poorly drained soil is the most probable cause setting the microbial community of that soil apart from those in the better drained soils. Our investigation suggests that not all indicators of microbial diversity share the same sensitivity to seasonal and drainage‐related soil moisture variations.

Psychiatric Health, Life Skills, and Opportunities for Wellness Program: Addressing psychiatric need through integrated consultation, collaboration, and brief episodes of care.

Integrated behavioral health programs bring strong benefits to patients and health organizations including reductions in overall costs. However, obstacles to funding prevent the implementation and maintenance of these programs across the country. The Psychiatric Health, Life Skills and Opportunities for Wellness (PHLOW) Program is based on the collaborative care model and seeks to provide psychiatric care through an integrated model that is financially sustainable for the organization. This pilot observational study included patients who received psychiatric care indirectly via consultations with primary care providers and directly through brief episodes of care. Patient outcomes were demonstrated by score changes on the nine-item Patient Health Questionnaire and Generalized Anxiety Disorder 7 before and after participation in brief episodes of care. Overall cost of care savings was demonstrated through change over time in risk-adjusted per-member-per-month. Patients participating in the PHLOW program showed potential drops in anxiety and depression ratings, coinciding with a reduction in mental health claims. In addition, participation in the program involved a small number of patient visits and prevented referrals to long-term psychiatry, preserving access for higher acuity presentations. This demonstration of the value of the PHLOW program has led to additional financial support of the program through the primary regional Medicaid payor, enhancing sustainability, and potentially modeling a collaboration that may be feasible for other organizations implementing integrated behavioral health programs. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Insights into the pore structure effect on the mass transfer of fuel cell catalyst layer via combining machine learning and multiphysics simulation

Analysis of the catalytic layer (CL) pore structure and three-phase (electron phase, proton phase, and reactant phase) mass transfer in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) is critical for improving concentration polarization and optimizing performance. However, there is a lack of studies on the pore structure’s impact on the catalytic layer three-phase mass transfer. In this work, the influence of pore structure on catalytic layer three-phase mass transfer and multiphysics distribution was investigated by combining machine learning and multiphysics simulation. Among many key factors investigated by machine learning that impact the performance of catalytic layer, porosity emerges as the primary influencing factor. Porosity accounts for 32.7 % of the electric potential drop, with macro/micro porosity contributing 27.6 % and 5.1 %, and 32.8 % of the current density, with macro/micro porosity contributing 15.6 % and 17.2 %. Furthermore, the macropore structure has a much greater influence on the performance of the catalytic layer compared to the micropore structure. Moreover, the simulation results demonstrated that porosity has a great influence on three-phase mass transfer, the oxygen molarity increases with increasing porosity. The electric potential difference increases exponentially as porosity increases. The relationship between current density and porosity is a volcanic relationship, which can be expressed as a quadratic polynomial function. The mesoscopic pore-scale model (PSM) with an εeff of 0.502 (εmic of 0.2 and εmac of 0.378) exhibits the highest mean current density at 619.526 mA/cm2@0.5 V, attributed to a more uniform and efficient three-phase transfer path. The accuracy of the mesoscopic pore-scale model and the polynomial equation is further confirmed through corresponding experiments. The experiment results show that the current density decreased as the εeff increased from 0.682 to 0.702, which aligns with the theoretical predictions of the PSM model and polynomial equation. These studies are valuable for comprehending the internal three-phase mass transfer behavior and optimizing the catalytic layer pore structure to enhance HT-PEMFC performance.

Understanding the Impact of SAM Fermi Levels on High Efficiency p-i-n Perovskite Solar Cells.

Completing the picture of the underlying physics of perovskite solar cell interfaces that incorporate self-assembled molecular layers (SAMs) will accelerate further progress in p-i-n devices. In this work, we modified the Fermi level of a nickel oxide-perovskite interface by utilizing SAM layers with a range of dipole strengths to establish the link between the resulting shift of the built-in potential of the solar cell and the device parameters. To achieve this, we fabricated a series of high-efficiency perovskite solar cells with no hysteresis and characterized them through stabilize and pulse (SaP), JV curve, and time-resolved photoluminescence (TRPL) measurements. Our results unambiguously show that the potential drop across the perovskite layer (in the range of 0.6-1 V) exceeds the work function difference at the device's electrodes. These extracted potential drop values directly correlate to work function differences in the adjacent transport layers, thus demonstrating that their Fermi level difference entirely drives the built-in potential in this device configuration. Additionally, we find that selecting a SAM with a deep HOMO level can result in charge accumulation at the interface, leading to reduced current flow. Our findings provide insights into the device physics of p-i-n perovskite solar cells, highlighting the importance of interfacial energetics on device performance.

An Improved Drift Theorem for Balanced Allocations

In the balanced allocations framework, there are \(m\) jobs (balls) to be allocated to \(n\) servers (bins). The goal is to minimize the gap , the difference between the maximum and the average load. In 2015, Peres, Talwar and Wieder used the hyperbolic cosine potential function to analyze the challenging case where \(m\gg n\) , for a large family of processes, including the \((1+\beta)\) -process and graphical balanced allocations. The key ingredient was to prove that the potential drops in every step, i.e., a drift inequality . In this work, we improve the drift inequality so that (i) it is asymptotically tight (leading to tighter gap bounds), (ii) it assumes weaker preconditions (thereby resolving an open problem regarding weighted graphical allocations), (iii) it applies not only to processes allocating to more than one bin in a single step but also (iv) to processes allocating a varying number of balls depending on the sampled bin. Our applications include the aforementioned large family of processes, and also several new processes and settings, including outdated information and memory. We hope that our techniques can be used to analyze further interesting settings and processes.

Voltage-Driven Molecular Photoelectrocatalysis of Water Oxidation.

Molecular photocatalysis and photoelectrocatalysis have been widely used to conduct oxidation-reduction processes ranging from fuel generation to electroorganic synthesis. We recently showed that an electrostatic potential drop across the double layer contributes to the driving force for electron transfer (ET) between a dissolved reactant and a molecular catalyst immobilized directly on the electrode surface. In this article, we report voltage-driven molecular photoelectrocatalysis with a prevalent homogeneous water oxidation catalyst, (bpy)Cu (II), which was covalently attached to the carbon surface and exhibited photocatalytic activity. The strong potential dependence of the photooxidation current suggests that the electrostatic potential drop across the double layer contributes to the driving force for ET between a water molecule and the excited state of surface-bound (bpy)Cu (II). Scanning electrochemical microscopy (SECM) was used to analyze the products and determine the faradaic efficiencies for the generation of oxygen and hydrogen peroxide. Unlike electrocatalytic water oxidation by (bpy)Cu (II) in the dark, which produces only O2, the voltage-driven photooxidation includes an additional 2e- pathway generating H2O2. DFT calculations show that the applied voltage and the presence of light can alter the activation energy for the rate-determining water nucleophilic attack steps, thereby increasing the reaction rate of photo-oxidation of water and opening the 2e- pathway. These results suggest a new route for designing next-generation hybrid molecular photo(electro)catalysts for water oxidation and other processes.

Calibrated the direct current potential drop method for fatigue crack propagation testing of nickel-based superalloy with film cooling hole

Turbine blades in aviation engines commonly feature a nickel-based superalloy structure integrated with film cooling holes to enhance inlet gas temperature. However, the presence of these film cooling holes often results in frequent occurrences of fracture failures nearby. The direct current potential drop (DCPD) method, renowned for its exceptional crack sensitivity, is frequently utilized for crack length monitoring. This study establishes a FEM model of the film cooling hole plate specimen to determine the optimal probe point location. Subsequently, a mapping relationship is derived to calibrate Johnson’s formula, accounting for the unequal crack lengths at the edges of film cooling holes. It is confirmed that the crack length measured by the DCPD method represents the cumulative crack lengths on both sides of the hole. Fatigue crack propagation experiments are then conducted, with crack length monitored using a microscope. The results affirm the successful application of the calibrated formula to the film cooling hole plate specimen, exhibiting an average error within 0.1 mm.

Characterization of Mn3O4/(x)Nb2O5 thin films as a promising material for supercapacitors

The thin films of Mn3O4/(x)Nb2O5 oxides (x = 0, 2, 4, and 6 %) were prepared by the electron beam evaporation method and then annealed at 400 °C. The structural analysis showed a tetragonal phase of Mn3O4, according to X-ray diffraction results. The quantitative elemental analysis of films confirms the stoichiometry of the Mn3O4, while the Nb2O5 couldn’t be recognized using energy dispersive X-ray fluorescence. The chemical speciation of the films was investigated using X-ray photoelectron spectroscopy. Three oxidation states of Mn were recognized at average binding energies of 645.70±0.35, 642.99±0.40, and 641.58±0.48 eV that correlated to Mn4+, Mn3+, and Mn2+, respectively. As the Nb2O5 increases, a slight decrease in the binding energy of Mn4+ is recognized, whereas it is nearly constant for the deconvoluted Mn3+ and Mn2+. Two electronic transitions (Eg1 and Eg2) of the optical band gap showed an increase with increasing Nb2O5 dopant from 2 % to 6 %. The optical parameters such as Eosc, the single oscillator energy, Edis, the dispersion energy, both moments (M−1) and (M−3), the ratio of carrier concentration/effective mass (N/m*), and the lattice dielectric constant (εL) were determined. From electrochemical measurements of pure Mn3O4 films, it is found that the voltammetric current density is directly proportional to the scan rates of cyclic voltammetry CV, with good cyclic stability, and by increasing the scan rates, the values of specific capacitance decrease while the values of specific power increase. In doped thin films, no potential drop is observed in the discharging process, which indicates good interfacial contact between the active material and the substrate during the charge/discharge process. These results suggest that the obtained Mn3O4 nanoparticles are a better candidate for supercapacitor applications.

Plasma potential and ion energy characteristics in BP-HiPIMS discharge with double layer

Abstract As an emerging ion acceleration plasma source, the bipolar-pulse high power impulse magnetron sputtering (BP-HiPIMS) discharge has been widely studied by academia and industry due to its ability to adjust the ion kinetic energy. Formation of the double layer (DL) potential structure during the BP-HiPIMS positive pulse is vital for accelerating ions, but its structural characteristics are still unclear. In this work, to understand the DL characteristics affected by various discharge parameters, the evolution of plasma potential V p and ion energy in BP-HiPIMS discharge with copper target has been investigated systematically using an emissive probe and mass spectrometer together. Spatial plasma potential measurements show that the DL is established in front of the target during the positive pulse, whose boundary potential drop U DL to accelerate ions can be increased to ∼60 V at a lower operating gas pressure (p= 0.6 Pa) and a higher applied positive pulse voltage (U + = 200 V). The ignition onset time of DL after applying the positive pulse can be shortened to ∼25 μs by decreasing the gas pressure and increasing the positive pulse voltage or negative pulse duration. After DL ignition, a group of high-energy copper ions with energy higher than the surrounding plasma potential can be recognized in the ion energy distribution function curves in the downstream plasma. This result illustrates that the copper ions can be ionized in the high-potential plasma region and be accelerated by the DL boundary potential drop. In addition, a global current balance model of the DL in BP-HiPIMS is developed, which suggests that the U DL can be well adjusted by increasing the positive pulse voltage U + especially for U + > 200 V as verified by the experimental potential measurements. All results suggest that the copper particles play an important role in the formation of DL and the DL plays an important role in accelerating copper ions.

Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted‐V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc

AbstractWe present an event based on Reimei satellite observations in the low‐altitude midnight auroral region, showing that intense and clear energy‐dispersed electron precipitations, repetitively generated by field‐aligned accelerations due to dispersive Alfvén waves, were modulating inverted‐V electrons. These Alfvénic electrons had peak energies equal to or slightly larger than those of the inverted‐Vs and were associated with the filamentary auroral forms rapidly streaming at the poleward edge of a broad discrete arc. This arc was caused by the inverted‐V accompanied by ion depletions produced by quasi‐electrostatic parallel potential drop. Assuming instantaneous electron accelerations over a wide energy range in a single location and a simple time‐of‐flight effect for the energy‐time dispersions, the Alfvénic source distances were estimated 1,500 ± 500 km above the satellite altitude of ∼676 km, a lower bound since the interaction locations are realistically distributed in altitudinally extended regions. The electron characteristics in detailed energy‐pitch angle distributions obtained at high time resolution can be categorized into: (a) original inverted‐V fluxes energized by quasi‐electrostatic upward electric field, (b) accelerated and decelerated/reduced inverted‐V fluxes, (c) field‐aligned energy‐dispersed precipitations accelerated by dispersive Alfvén waves, and (d) upwelling secondary components effectively produced by the field‐aligned precipitations particularly at energies of a few tens of eV. This event is useful to reveal the interactions between the inverted‐V and Alfvénic electrons and their related ionospheric effects in the magnetosphere‐ionosphere coupling processes. The detailed energy‐pitch angle distributions presented here provide constraints for models of these interactions and processes.

Analysis of electroviscous effects in electrolyte liquid flow through a heterogeneously charged uniform microfluidic device

Charge-heterogeneity (i.e., surface charge variation in the axial direction of the device) introduces non-uniformity in flow characteristics in the microfluidic device. Thus, it can be used for controlling practical microfluidic applications, such as mixing, mass, and heat transfer processes. This study has numerically investigated the charge-heterogeneity effects in the electroviscous (EV) flow of symmetric (1:1) electrolyte liquid through a uniform slit microfluidic device. The Poisson’s, Nernst-Planck (N-P), and Navier–Stokes (N-S) equations are numerically solved using the finite element method (FEM) to obtain the flow fields, such as total electrical potential (U), excess charge (n *), induced electric field strength (E x), and pressure (P) fields for following ranges of governing parameters: inverse Debye length (2 ≤ K ≤ 20), surface charge density (4 ≤ S 1 ≤ 16), and surface charge-heterogeneity ratio (0 ≤ S rh ≤ 2). Results have shown that the total potential (∣ΔU∣) and pressure (∣ΔP∣) drop maximally increase by 99.09% (from 0.1413 to 0.2812) (at K = 20, S 1 = 4) and 12.77% (from 5.4132 to 6.1045) (at K = 2, S 1 = 8), respectively with overall charge-heterogeneity (0 ≤ S rh ≤ 2). Electroviscous correction factor (Y, i.e., ratio of effective to physical viscosity) maximally enhances by 12.77% (from 1.2040 to 1.3577) (at K = 2, S 1 = 8), 40.98% (from 1.0026 to 1.4135) (at S 1 = 16, S rh = 1.50), and 41.35% (from 1 to 1.4135) (at K = 2, S rh = 1.50), with the variation of S rh (from 0 to 2), K (from 20 to 2), and S 1 (from 0 to 16), respectively. Further, a simple pseudo-analytical model is developed to estimate the pressure drop in EV flow, accounting for the influence of charge-heterogeneity based on the Poiseuille flow in a uniform channel. This model predicts the pressure drop ± 2%–4% within the numerical results. The robustness and simplicity of this model enable the present numerical results for engineering and design aspects of microfluidic applications.

ANT-Mediated Inhibition of the Permeability Transition Pore Alleviates Palmitate-Induced Mitochondrial Dysfunction and Lipotoxicity.

Hyperlipidemia is a major risk factor for vascular lesions in diabetes mellitus and other metabolic disorders, although its basis remains poorly understood. One of the key pathogenetic events in this condition is mitochondrial dysfunction associated with the opening of the mitochondrial permeability transition (MPT) pore, a drop in the membrane potential, and ROS overproduction. Here, we investigated the effects of bongkrekic acid and carboxyatractyloside, a potent blocker and activator of the MPT pore opening, respectively, acting through direct interaction with the adenine nucleotide translocator, on the progression of mitochondrial dysfunction in mouse primary lung endothelial cells exposed to elevated levels of palmitic acid. Palmitate treatment (0.75 mM palmitate/BSA for 6 days) resulted in an 80% decrease in the viability index of endothelial cells, which was accompanied by mitochondrial depolarization, ROS hyperproduction, and increased colocalization of mitochondria with lysosomes. Bongkrekic acid (25 µM) attenuated palmitate-induced lipotoxicity and all the signs of mitochondrial damage, including increased spontaneous formation of the MPT pore. In contrast, carboxyatractyloside (10 μM) stimulated cell death and failed to prevent the progression of mitochondrial dysfunction under hyperlipidemic stress conditions. Silencing of gene expression of the predominate isoform ANT2, similar to the action of carboxyatractyloside, led to increased ROS generation and cell death under conditions of palmitate-induced lipotoxicity in a stably transfected HEK293T cell line. Altogether, these results suggest that targeted manipulation of the permeability transition pore through inhibition of ANT may represent an alternative approach to alleviate mitochondrial dysfunction and cell death in cell culture models of fatty acid overload.

Development and Testing of a Helicon Plasma Thruster Based on a Magnetically Enhanced Inductively Coupled Plasma Reactor Operating in a Multi-Mode Regime

A disruptive Electric Propulsion system is proposed for next-generation Low-Earth-Orbit (LEO) small satellite constellations, utilizing an RF-powered Helicon Plasma Thruster (HPT). This system is built around a Magnetically Enhanced Inductively Coupled Plasma (MEICP) reactor, which enables acceleration of quasi-neutral plasma through a magnetic nozzle. The MEICP reactor features an innovative design with a multi-dipole magnetic confinement system, generated by neodymium iron boron (NdFeB) permanent magnets, combined with an azimuthally asymmetric half-wavelength right (HWRH) antenna and a variable-section ionization chamber. The plasma reactor is followed by a solenoid-free magnetic nozzle (MN), which facilitates the formation of an ambipolar potential drop, enabling the conversion of electron thermal energy into ion beam energy. This study explores the impact of an inhomogeneous magnetic field on the heating mechanism of the HPT and highlights its multi-mode operation within a pulsed power range of 200 to 500 W of RF. The discharge state, characterized by high-energy electron-excited ions and low-energy excited neutral particles in the plasma plume, was analyzed using optical emission spectroscopy (OES). The experimental testing campaign, conducted under pulsed power excitation, reveals that, as RF input power increases, the MEICP reactor transitions from inductive (H-mode) to wave coupling (W-mode) discharge modes. Spectrograms, electron temperature, and plasma density measurements were obtained for the Helicon Plasma Thruster within its operational envelope. Based on OES data, the ideal specific impulse was estimated to exceed 1000 s, highlighting the significant potential of this technology for future LEO/VLEO space missions.

Linear dependence of potential drop at the passive film/solution interface on film-formation potential and pH: Combining first-principles calculations with experiments

Potential drop at the oxide film/solution interface plays a critical part in numerous electrochemical processes, especially for the passivated metal-electrolyte system, affecting the passive film breakdown and the pitting initiation. There are still some controversies over the dependence of potential drop at the passive film/solution interface (φf/s) on potential and pH of electrolyte. Herein, we develop a model presenting the linear dependence of φf/s on both potential and pH, as represented by φf/s=φf/s(V=0,pH=0)0+αV+βpH. By analyzing the surface charge (i.e., point of zero charge, pHpzc) and performing first-principles calculations, we provide the insights into the effect of potential and pH on the φf/s, and into the linear relation between φf/s with pH beyond the Nernst relation that is attributed to the role of point defects in pHpzc of passive film on iron. In addition, two methods, e.g., a combination of Mott-Schottky measurement with first-principles, contact angle titration, are suggested to determine the values of α, β and φf/s(V=0,pH=0)0, respectively. The study of passivity of iron in borate buffer solutions validates our model.

Tunable electronic and optical properties of a Type-ⅡViolet Phosphorus/MoS2 heterojunction: First-principles calculation

Photodetectors based on heterostructures have garnered significant research interest due to their superior self-powering and responsiveness capabilities. In this work, the optoelectronic properties of a violet phosphorus (VP/MoS2)/MoS2 heterojunction are investigated through first-principles calculations. The results reveal that the VP/MoS2 heterojunction possesses an indirect bandgap and a type-II band alignment. The interface potential drop (Ep) of the VP/MoS2 heterojunction is 5.45 eV by studying the interfacial interaction, suggesting the formation of a large in-built electric field and an excellent self-powering capability. The absorption coefficient of VP/MoS2 heterojunction are significantly higher in the UV and visible regions. Under biaxial strain, the VP/MoS2 heterostructure can undergo transformations from a semiconductor to a metal, from an indirect to a direct bandgap, and from a type-II to a type-I energy band structure. Moreover, the light trapping ability in the near-infrared region is significantly enhanced. These findings underscore the broader potential application of VP/MoS2 heterostructures in high-performance optoelectronic devices.

Полевая электронная спектроскопия молекулярно-напыленного оксидного термокатода

The results of a study of the emission characteristics of a molecular-sprayed oxide thermocathode based on triple carbonate of alkaline earth metals with an emission layer thickness of ~1 µm in the operating temperature range of 590-730 °C. are presented. The results are in good agreement with those obtained earlier for a serial oxide thermocathode with an emission layer thickness of ~100 µm applied by pulverization, and correspond to the model of a "spotted cathode" - a superposition of emission spots at different stages of activation. An idea of the activation phenomenon occurring at a given temperature in a certain range of values of the electric field strength on the surface of emission spots is detailed both with an increase and a decrease in the anode voltage. The energy spectra of the emitted electrons of a separate emission spot with a half-height width of ~100 meV have been obtained. The values of the potential change of the emitting surface of the cathode within the probed region of 0.9 V and the potential drop on the emission layer under the probed region of 4.1 V were measured.

A life prediction model for P110S steel in deep-well environments with H2S/CO2 coexistence based on multi-factor chemometric drive

A mechanistic-chemometrics model for life prediction of P110S steel in deep-well environments with H₂S/CO₂ coexistence was proposed. The model was developed by considering the interaction mechanism between uniform and pitting corrosion, then modified using a multi-factor chemometric drive incorporating temperature/pressure, flow velocity, stress. Finally, the pit-to-crack transition was modeled using finite element design and direct current potential drop measurements, completing the life prediction process. The model predicts a lifespan of 2.28–5.25 years at different well depths, and this result was validated with on-site data, indicating the model’s accuracy. The knowledge paradigm provided herein will assist in corrosion prediction.

Semi-analytical modeling of prompt redeposition in a steady-state plasma

Abstract A steady-state, 1D semi-analytical model for prompt redeposition based on the separation between redeposition caused by the electric field in the sheath and redeposition related to gyromotion is here described. The model allows for the estimation of not only the fraction of promptly redeposited flux but also the energy and angular distribution of the non-promptly redeposited population, along with their average charge state. Thus, the temperature and mean parallel-to-B velocity of the non-promptly redeposited flux are also available. The semi-analytical model was validated against equivalent Monte Carlo simulations across a broad range of input parameters. In this paper the eroded material under exam was tungsten (W) for which the code demonstrated consistent agreement with respect to numerical results, within its defined validity limits. The model can theoretically provide a solution for any material, temperature and electron density profile in the sheath, monotonic potential drop profile, and sputtered particles energy and angular distribution at the wall. As such, this code emerges as a potential tool for addressing the boundary redeposition phenomenon in fluid impurity transport simulations.

Theoretical Study on Photocatalytic Reduction of CO2 on Anatase/Rutile Mixed-Phase TiO2.

The construction of anatase/rutile heterojunctions in TiO2 is an effective way of improving the CO2 photoreduction activity. Yet, the origin of the superior photocatalytic performance is still unclear. To solve this issue, the band edges between anatase and rutile phases were theoretically determined based on the three-phase atomic model of (112)A/II/(101)R, and simultaneously the CO2 reduction processes were meticulously investigated. Our calculations show that photogenerated holes can move readily from anatase to rutile via the thin intermediated II phase, while photoelectrons flowing in the opposite direction may be impeded due to the electron trapping sites at the II phase. However, the large potential drop across the anatase/rutile interface and the strong built-in electric field can provide an effective driving force for photoelectrons' migration to anatase. In addition, the II phase can better enhance the solar light utilization of (112)A/(100)II, including a wide light response range and an intensive optical absorption coefficient. Meanwhile, the mixed-phase TiO2 possesses negligible hydrogenation energy (CO2 to COOH*) and lower rate-limiting energy (HCOOH* to HCO*), which greatly facilitate CH3OH generation. The efficient charge separation, strengthened light absorption, and facile CO2 reduction successfully demonstrate that the anatase/rutile mixed-phase TiO2 is an efficient photocatalyst utilized for CO2 conversion.