Charge Separation Effects Research Articles

Efficient degradation of organic dyes and reduced Cr(VI) in environmental water purification by in-situ deposition of silver nanoparticles on polydopamine-modified M-ATP/PCN

This paper presents the synthesis of Ag@PDA/M-ATP/PCN photocatalysts for the removal of heavy metals and organic dyes via the in-situ reduction method. According to the photoluminescence (PL) spectra, time-resolved fluorescence spectra, UV–vis absorption spectra, transient photocurrent response spectra, and the EIS results, the composite of M-ATP, PDA coating, and single-atom Ag doping further promotes the separation of the photogenerated carriers, reduces the band-gap, improves the photocatalytic performance, and promotes the synergistic effect of charge separation and transfer to enhance the photocatalytic performance. The catalysts prepared by this composite strategy exhibit high charge separation efficiency, higher catalytic efficiency, and better stability than the conventional single-method modified polymeric carbon nitride catalysts.

Engineering Heterostructures of Layered Double Hydroxides and Metal Nanoparticles for Plasmon-Enhanced Catalysis

Artificially designed heterostructures formed by close conjunctions of plasmonic metal nanoparticles (PNPs) and non-plasmonic (2D) lamellar nanostructures are receiving extensive interest. The synergistic interactions of the nanounits induce the manifestation of localized surface plasmon resonance (LSPR) in plasmonic metals in the specific environment of the 2D-light absorbing matrix, impacting their potential in plasmon enhanced catalysis. Specifically, layered double hydroxides (LDH) with the advantages of their unique 2D-layered structure, tuned optical absorption, ease of preparation, composition diversity, and high surface area, have emerged as very promising candidates for obtaining versatile and robust catalysts. In this review, we cover the available PNPs/LDH heterostructures, from the most used noble-metals plasmonic of Au and Ag to the novel non-noble-metals plasmonic of Cu and Ni, mainly focusing on their synthesis strategies toward establishing a synergistic response in the coupled nanounits and relevant applications in plasmonic catalysis. First, the structure–properties relationship in LDH, establishing the desirable features of the 2D-layered matrix facilitating photocatalysis, is shortly described. Then, we address the recent research interests toward fabrication strategies for PNPs/support heterostructures as plasmonic catalysts. Next, we highlight the synthesis strategies for available PNPs/LDH heterostructures, how these are entangled with characteristics that enable the manifestation of the plasmon-induced charge separation effect (PICS), co-catalytic effect, or nanoantenna effect in plasmonic catalysis with applications in energy related and environmental photocatalysis. Finally, some perspectives on the challenges and future directions of PNPs/LDHs heterostructures to improve their performance as plasmonic catalysts are discussed.

Synergistic Effect of Charge Separation and Multiple Reactive Oxygen Species Generation on Boosting Photocatalytic Degradation of Fluvastatin by ZnIn2S4/Bi2WO6 Z-Scheme Heterostructured Photocatalytst.

The application of semiconductor photocatalysts with narrow band gaps is hindered by the rapid recombination of electron–hole pairs and limitation of multiple reactive oxygen species (ROS) synchronous generation. A n–n-type direct Z-scheme heterostructured photocatalyst was constructed based on the staggered band alignment of bismuth tungstate (Bi2WO6) and indium zinc sulfide (ZnIn2S4) to reveal the synergistic effect of charge separation and multiple ROS synchronous generation on boosting photocatalytic performance. Under irradiation, electrons in the conduction band (CB) of Bi2WO6 and holes in the valence band (VB) of ZnIn2S4 recombined at interface to prolong the lifetime of electrons in the CB of ZnIn2S4 and holes in the VB of Bi2WO6. Meanwhile, the multiple ROS synchronously generated to oxidize pollutant due to the strong redox ability of electrons of ZnIn2S4 and holes of Bi2WO6, which was determined by the CB potential of ZnIn2S4 and VB potential of Bi2WO6. The results provided valuable insights for the application of photocatalysts with a narrow band gap in the field of water pollution control.

RETRACTED: Highly operative NiO/ZnO nanocomposites for photocatalytic removal of azo dye

The far-reaching technology of semiconductors in treating water pollutants reduces serious health hazards to humans and other eco-systems. With this interpretation, this work is attempted for the first time to synthesize nanosized pristine NiO and ZnO materials, and NiO/ZnO (70:30, 50:50) composites by co-precipitation method. The synthesized materials were then portrayed for their properties using various instrumental techniques such as X-ray diffraction (XRD), Transmission electron microscope (TEM), Energy dispersive X-ray spectrum (EDXS), Fourier transform Infrared spectrum (FT-IR). The main approach of this work is connected with the ultra violet (UV) photocatalytic degradation of MO (methyl orange) by employing the synthesized nanomaterials as catalysts. In view of results, the photocatalytic degradation of NiO/ZnO (70:30) has reported the greatest efficiency than the other catalysts. This outcome lies with the consideration of higher content of NiO present in the composite than ZnO. Further, there was the existence of higher surface area analysed from the BET result. Also, the NiO/ZnO (50:50) sample showed lower degradation efficiency in terms of formed agglomeration when surveyed through TEM. Besides, the positive mechanism of photocatalysis reaction forms the essential hydroxyl radicals which correspond to MO degradation. Moreover, the highly efficient NiO/ZnO (70:30) sample has been trialled for photocatalytic repetition process to observe the stability of degradation. It has accounted with good efficiency for 5 repeated cycles. Finally for UV degradation, the recognized photocatalytic aspect was due to the surface morphology enhanced surface area, synergistic effects of metal oxides and electron-hole charge separation.

Efficient charge separation in sulfur doped AgFeO2 photocatalyst for enhanced photocatalytic U(VI) reduction: The role of doping and mechanism insights

Photocatalytic reduction of U(VI) in aqueous solutions has been considered as an efficient and promising technology to solve radioactive U pollution. In this work, density functional theory (DFT) calculations were firstly employed to optimize and compare the adsorption configurations combined uranium with four given photocatalysts, then their adsorption energies were − 0.97 eV for AgFeO2, − 1.15 eV for Zn doped AgFeO2, − 1.73 eV for Cu doped AgFeO2 and − 2.66 eV for S doped AgFeO2, respectively, indicating the sulfur doping plays a major role in U(VI) photoreduction. Herein, a visible light responsive efficient sulfur doped AgFeO2 photocatalyst (S doped AgFeO2) was synthesized and utilized to photocatalytic reduction of U(VI) in aqueous solutions. According to XRD, XPS and TEM analysis, the sulfur was successfully doped in AgFeO2 via the hydrothermal method. The batch experimental showed that S doping enhanced the U(VI) photoreduction activity of AgFeO2, and the S-AFO-3 photocatalyst exhibited the highest photocatalytic activity (92.57%), which was 1.5 times than that of pure AgFeO2. ESR, PL and DFT results demonstrated that the enhancement of adsorbed U(VI) photoreduction was attributed to the own unique effect of oxygen vacancy defects and efficient charge separation of S doped AgFeO2 photocatalyst. Due to its higher adsorption energies, fast-U(VI) photoreduction rate and superior chemical stability, the sulfur doped AgFeO2 photocatalyst is hoped for water remediation containing U(VI) wastewater.

Magnetosonic Shocks and Solitons in Fermi Plasma With Quasiperiodic Perturbation

In this article, we consider a dense stellar plasma consisting of predominantly electrons, positrons, and ions under the action of the magnetic field of the star. We derived the Korteweg–de Vries Burgers (KdV-Burgers) equations by using the reductive perturbation technique and obtained shock and solitary profiles for magnetoacoustic waves. We further studied the self-interaction of such stationary formations and the amplitude modulated envelope solitons. The possibility of a rogue wave-like structure is also discussed. To understand the physical problem in greater detail, we studied the Hamiltonian formulation to study stability. We studied how modulational instability can lead to the formation of rogue waves by investigating the nonlinear Schrodinger equation. In addition, drift-like instability showing the density and charge separation effects in plasma has been studied. The results will be helpful to interpret magnetoacoustic wave formations in solar corona or other stellar entities and can help in the study of inhomogeneous plasmas in laboratory and fusion reactors. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PACS</i> —52.35.Fp, 03.50.De, 41.20.-q, 52.30.Cv, 47.85.Dh, 52.35.Hr, 52.27.Ep, 52.30.-q, 52.35.Tc, and 52.35.Sb.

Eliminating finite-grid instabilities in gyrokinetic particle-in-cell simulations

Finite-grid (aliasing) instabilities are known to place severe limitations on momentum-conserving particle-in-cell (PIC) methods applied to models including charge separation effects by requiring the resolution of the Debye length. Gyrokinetic models, on the other hand, generally enforce quasi-neutrality thereby removing the Debye length analytically. Recent studies with momentum-conserving PIC applied to gyrokinetic models, however, show that a manifestation of this instability exists in certain physical parameter regimes for arbitrary spatial resolution. In this paper, we show that a simple reformulation of the discrete equations, making use of a co-located discretization of the continuity equation, eliminates this instability for all practical purposes. We perform numerical dispersion analyses for both the original and reformulated schemes, including the effects of finite mean parallel velocity and finite β. We demonstrate that the reformulated scheme is numerically stable for stationary plasmas at any spatial resolution and for plasmas in which the electron mean parallel velocity is smaller than the electron thermal velocity (generally ensured by ambipolarity in plasmas of interest). This reformulation may be particularly useful for codes with complicated meshes, where high-order shape functions or energy-conserving schemes are difficult to implement. The analysis presented here may also be useful for explaining the success of previously considered methods to remove particle instabilities, such as the split-weight scheme.

Tip-induced directional charge separation on one-dimensional BiVO4 nanocones for asymmetric light absorption

One dimensional (1D) semiconductor is a class of extensively attractive materials for many emerging solar energy conversion technologies. However, it is still of shortage to assess the impact of 1D structural symmetry on spatial charge separation and understand its underlying mechanism. Here we take controllably-synthesized 1D BiVO4 nanocones and nanorods as prototypes to study the influence of 1D symmetry on charge separation. It is found that the asymmetric BiVO4 nanocones enable more effective charge separation compared with the symmetric nanorods. The unexpected spatial charge separation on the nanocones is mainly ascribed to uneven light absorption induced diffusion-controllable charge separation due to symmetry breaking of 1D nanostructure, as evidenced by spatial and temporal resolved spectroscopy. Moreover, the promotion effect of charge separation on the nanocones was quantitatively evaluated to be over 20 times higher than that in BiVO4 nanorods. This work gives the first demonstration of the influence of 1D structural symmetry on the charge separation behavior, providing new insights to design and fabricate semiconductor materials for efficient solar energy conversion.

Charge separation effect in the nanocomposites of Co3O4-QDs: visible light photocatalytic dye degradation in aqueous solutions.

Photo-treatment of water is a promising environmentally friendly process that provides clean water and makes wastewater reusable in industry. Thus, efforts toward finding highly efficient photocatalysts have gained a huge attention to remove the organic contaminants in water. Quantum dots (QDs) are extensively utilized for photocatalytic remediation regarding their prominent optical, electrical, and chemical properties. Herein, we report the highly efficient and environmentally friendly synthesis of Co3O4-QDs-based graphene quantum dots (GQDs) and infinite coordination polymer comprising Zn nodes (Zn-ICP) nanocomposites as active and robust photocatalysts for photo-assisted water treatment. The pristine Co3O4-QDs, GQDs, and Zn-ICP showed lower activity under visible light. However, after functionalization of GQDs and Zn-ICP with Co3O4-QDs, the activity increased, and more photocatalytic efficiency was achieved. For instance, Zn-ICP, GQDs, Co3O4-QDs, Co3O4-QDs/Zn-ICP, and Co3O4-QDs/GQD degraded 21, 19, 52, 73, and 83% of rhodamine B (RhB) and 34, 46, 50, 73, and 76% of methylene blue (MB) after 60min. The high photocatalytic efficiency was ascribed to the conjugation of Co3O4-QDs with GQDs and Zn-ICP which causes efficient absorption of visible light. The existence of Co3O4-QDs was found to be essential not only for effective charge separation but also widening the region of light absorption followed by increase in photocatalytic performances. Charge separation in photocatalytic reactions, energy levels of nanocomposites, and mechanism of the photocatalytic process were investigated by photoluminescence spectra (PL), Mott-Schottky, electrochemical impedance (EIS), and diffuse reflectance UV-Vis spectroscopy (DRS).

Construction of a ternary WO3/CsPbBr3/ZIF-67 heterostructure for enhanced photocatalytic carbon dioxide reduction

Using halide perovskite nanomaterials for solar-to-fuel conversion has recently attracted a lot of attention due to their excellent photoelectric properties. However, severe photogenerated charge carrier recombinations and poor reaction kinetics greatly restrict their photocatalytic performance. In this study, a ternary WO3/CsPbBr3/ZIF-67 heterostructure was designed for efficient CO2 photoreduction. The results indicate that the Z-scheme charge transfer pathway constructed between WO3 and CsPbBr3 ensures the effective transfer and separation of photogenerated charge carriers. Meanwhile, the subsequent surface modification of zeolitic imidazolate frameworks (ZIF-67) with active Co centers further benefits CO2 adsorption and activation. Accordingly, the synergistic effects of charge separation and CO2 uptake greatly promote the photocatalytic activity. The optimal WO3/CsPbBr3/ZIF-67 heterostructure yields a CO production of 99.38 μmol g−1 in 3 h, which is 6.8 times of that produced by CsPbBr3. This work will inspire new insights in developing efficient photocatalysts for CO2 reduction and even more challenging photocatalytic reactions by elaborately regulating the functional ingredient.

Fe2 O3 /FePO4 /FeOOH Ternary Stepped Energy Band Heterojunction Photoanode with Cascade-Driven Charge Transfer and Enhanced Photoelectrochemical Performance.

Controlling the charge transfer pathway in semiconductors is an important method to improve charge separation efficiency and enhance photoelectrochemical activity. In this work, a Fe2 O3 /FePO4 /FeOOH nanorod photoanode with stepped energy band structure is prepared by a hydrothermal and water bath method. The charge separation efficiency of the ternary heterojunction is higher than that of the traditional type II heterojunction, which might be due to the efficient cascade charge transfer and separation effect of the ternary stepped energy band heterojunction. The H2 and O2 evolution rates for photoelectrochemical water splitting of Fe2 O3 /FePO4 /FeOOH photoanode are 0.247 and 0.111 μmol min-1 , which is 2.15 and 1.95 times that of the Fe2 O3 /FePO4 photoanode, respectively. The incident photocurrent efficiency (IPCE) of Fe2 O3 /FePO4 /FeOOH photoanode under 365 nm light irradiation is 1.5 and 1.8 times that of Fe2 O3 /FePO4 and Fe2 O3 /FeOOH photoanodes, respectively. This work provides an attractive strategy for solar energy conversion to construct efficient photoelectrochemical photoanode materials.

Ultrathin Bi2Se3/CdS composite for efficient photocatalytic hydrogen evolutionviahigh interfacial charge separation and photothermal effect

Ultrathin Bi2Se3nanosheets/CdS nanoparticles were prepared, which display excellent photocatalytic H2activity, ascribed to the synergistic mechanism of the unusual transfer process of high-energy electrons and the photothermal effect.

Synergistic Effect of Charge Separation and Multiple Reactive Oxygen Species Generation on Boost Photocatalytic Performance of the Direct Z-Scheme Heterostructured Photocatalytst

Synergistic Effect of Charge Separation and Multiple Reactive Oxygen Species Generation on Boost Photocatalytic Performance of the Direct Z-Scheme Heterostructured Photocatalytst

Uncovering the systematical charge separation effect of boron nitride quantum dots on photocatalytic performance of BiFeO3 perovskite towards degradation of tetracycline antibiotic

In this study, metal-free boron nitride quantum dots (BNQDs) were incorporated into the perovskite type BiFeO3 (BFO) structure by facile impregnation technique, which preserved promoted photo-Fenton catalytic activity towards tetracycline hydrochloride (TC-HCl) degradation under visible light irradiation. TEM images represented that BNQDs were uniformly loaded on the perovskite structure as dark dots with the average size of 3 nm, leading formation of BFO@BNQDs heterojunction catalyst. The diffractogram confirmed that the heterojunction sample crystallized well without deviation in the original cubic structure. The optical and photo-electrochemical analyses indicated that modifying perovskite structure with BNQDs significantly facilitated rapid charge transport due to the hole extracting ability of BNQDs yielding enhanced catalytic activity. In photo-Fenton catalytic experiments, 88% of TC-HCl was removed in BFO@BNQDs/1 system while it was 64% for raw BFO and the reaction rate constant of BFO@BNQDs was calculated 1.95 times higher than that of pure BFO. The catalytic activities of as-synthesized catalysts were also examined under different conditions namely solution pH, co-existing anion and water matrix. The high degradation rate (74.5%) was obtained in the sea water suggested a tremendous potential of BFO@BNQDs in practical utilization. The catalytic removal degree of 72% was still achieved at the end of the fourth cycle indicating great durability of heterojunction. After degradation, the mass spectra showed the possible degradation pathway of TC-HCl and the by-products were defined as less toxic after degradation for 120 min. These findings highlight the potential of boron nitride quantum dots in the development of efficient heterojunction photocatalysts.

Improved photocatalytic CO2 and epoxides cycloaddition via the synergistic effect of Lewis acidity and charge separation over Zn modified UiO-bpydc

CO2 cycloaddition reaction from propylene oxide and CO2 to cyclic carbonates is a desirable process to become carbon neutral. Photo energy can decrease the temperature and pressure needed for this reaction according to our previous results. However, the relationship between Lewis acidity and the photophysical process needs to be clarified and optimized. Hence, in this work, Zn is introduced into UiO-bpydc via the coordination of Zn with the bipyridyl group in bpydc. It is found that the introduction of Zn not only effectively activate propylene oxide, but also promote ligand to metal charge transfer (LMCT) process, which ultimately is beneficial for CO2 activation. However, Ce plays a negative effect under light irradiation. namely, the presence of Ce facilitates the energy transfer process rather than the LMCT process.

Synergetic intimate interface contacts of 2D/1D S-g-C3N4/Co-NiS heterojunction with spatial charge separation for boosting photodegradation of MB and inactivation of pathogens under visible light irradiation

The constricted visible light harvesting and undesirable rapid recombination of photogenerated e- and h+ set enormously hinder the activity of the photocatalysts. In this work, we design and develop two-dimensional/one-dimensional (2D/1D) S-g-C3N4/Co-NiS heterojunction with intimate heterointerface contact by self-assembly technique. The fast electron transportation of 2D S-g-C3N4 nanosheets (NSs) and the well-matched energy levels of bare S-g-C3N4 and 5% Co-NiS nanorods (NRs) cooperative support the transportation and separation of photo-carriers at the heterointerface of S-g-C3N4/Co-NiS. The as-fabricated samples were evaluated EDX, SEM, UV–vis, XRD, TEM, FTIR, XPS, BET, PL and transient photocurrent. Moreover, this well-defined construction boosts sunlight harvesting and exhibits a large surface area. Benefiting from the intimate coupling and structural features, the 20% S-g-C3N4/Co-NiS heterojunction attains a noteworthy photocatalytic methylene blue (MB) degradation rate of 100%, considerably improved than that of bare NiS (34%), 5% Co-NiS (57%) and pristine S-g-C3N4 (31%). Concurrently, the photocorrosion of bare S-g-C3N4 was suppressed by simultaneous integrating with NiS and engineering with cobalt, which was demonstrated through a chemical stability test with 6 consecutive experimental tests. Such outstanding enrichment in photocatalytic activity and chemical stability was primarily attributed to boosting spatial charge separation and synergistic effects of the 20% 2D/1D S-g-C3N4/Co-NiS nanocomposites (NCs). Antibacterial performance of 20% 2D/1D S-g-C3N4/Co-NiSNCs against 4 infectious species was evaluated in visible light radiance. Our results emphasize the great importance of the efficacious heterointerface blend of 2D/1D S-g-C3N4/Co-NiS NCs as a promising photocatalyst scheme for enhanced photocatalytic degradation of dye and disinfection of pathogens.

Emerging of Ag particles on ZnO nanowire arrays for blue-ray hologram storage

Noble-metal/metal-oxide-semiconductor nanostructures as an important material platform have been applied in massive data storage. ZnO exhibits excellent optical modulation ability. However, plasmon induced charge separation effect in Ag/ZnO systems is very weak due to the low chemical activity on surface of the oxide. Herein, we prepare ZnO nanowire arrays via the hydrothermal method, and measure their absorption spectra, photoluminescence spectra and electron paramagnetic resonance, proving the existence of oxygen defects in ZnO. Accordingly, an idea of “electron reverse transfer” is proposed such that blue-ray (403.4 nm) induces reduction of Ag+ ions through the excitation of ZnO. Rod-like and spherical silver nanoparticles emerge on the surface and in the gap of ZnO nanowire arrays, respectively, after the visible light stimulus. It is found that nanowire density, oxygen defects and surface roughness are dependent on hydrothermal time. The optimized diffraction efficiency of 0.08% is obtained for reconstructing hologram in the nanocomposite film. This work provides a bright way for construction of ZnO-based optoelectronic integrated devices.

Effect of Hydrophobicity and Charge Separation on the Antifouling Properties of Surface-Tethered Zwitterionic Peptides.

Zwitterionic peptides emerge as a class of highly effective antifouling material in a wide range of applications such as biosensors, biomedical devices, and implants. We incorporated neutral amino acid spacers with different hydrophobicities, including serine (Ser), glycine (Gly), and leucine (Leu), into zwitterionic peptides with lysine-glutamic acid repeating units and investigated the structure and antifouling performance of the zwitterionic peptide brushes by surface plasma resonance, surface force apparatus (SFA), and all-atomistic molecular dynamics (MD) simulation techniques. Our results demonstrate that the hydrophilicity of neutral spacers alters the structure and antifouling performance of the peptide-modified surface. Hydrophilic Ser-inserted peptides reduced the interaction between the peptide monolayer and protein foulants, while hydrophobic Leu significantly increased the protein adhesion. SFA force measurements show that the presence of more spacers would increase the adhesion between the peptide monolayer and the modeling foulant lysozyme, especially for the hydrophobic spacers. MD simulations reveal that hydrophilic Ser spacers retain the hydrophilicity of the peptide monolayer and improve the antifouling performance, and Gly spacers give rise to more interchain cross-links. Leu spacers result in a more hydrophobic peptide monolayer, which leads to dehydration of the peptide monolayer and reduces the antifouling performances.

Morphology dependent effective charge separation process in nanostructured MoS2 thin films for enhanced photodegradation behavior

2D-layered nanostructure-based advanced coatings are the most recent advancement in the field of advanced oxidation processes. Effective charge separation is one of the key parameters in enhancing the photodegradation ability of 2D-layered nanostructures. We report the cost-effective hydrothermal synthesis of MoS2 thin films on conductive ITO substrates with tunable morphology. Scanning electron microscopy studies manifested the modulation in the morphology of MoS2 thin films and confirmed the presence of spherical, thread, and sheet-like nanostructures under the evolution of precursor concentration. UV–visible absorption spectroscopy revealed the modulation in the optical absorption and effective bandgap narrowing with the changes in the surface morphology. The estimated bandgap value of MoS2 thin film samples varies from 1.82 to 1.69 eV. PL spectroscopy and electrochemical studies display the morphology-dependent charge separation behavior and confirm that the lowest recombination rate is attained by thread-like MoS2 nanostructures. Raman spectroscopy and x-ray photoelectron spectroscopy confirms the 2H phase of MoS2 thin films. MoS2 thin films with thread-like structures are found to be the most efficient for sunlight-induced photodegradation activity as compared to other MoS2 samples. Thread-like MoS2 structures containing MoS2 thin film with the highest charge transport properties decompose 85% of 5 µM methylene blue molecules and 90.4% of 5 µM rhodamine B molecule solution in 40 min and 80 min, respectively, under natural sunlight. The prominent charge separation effects on the enhanced photodegradation capabilities of MoS2 thin films due to distinct variations in morphology, which have not been reported till now, are explored precisely.

Direct evidence of gradient drift instability being the origin of a rotating spoke in a crossed field plasma

A plasma rotating spoke in a crossed field discharge is studied using 2D radial-azimuthal fully kinetic particle-in-cell Monte Carlo collision simulations. The kinetic model reveals the whole perturbation spectrum of the gradient drift instability in the linear stage: Simon–Hoh, lower hybrid, and ion sound modes, providing direct evidence of the spoke of gradient drift instability nature. The two-fluid dispersion relation of gradient drift instability was utilized to analyze the linear development of instabilities in the simulations. The charge separation effect was incorporated in the fluid linear theory and a super-resolution signal processing method (multiple signal classification) was applied to obtain the numerical frequency spectrum. The simulated spectrum and growth rate show excellent agreement with the theoretical dispersion relation (real frequency and imaginary frequency) in the investigated cases. The most linearly unstable mode was found to be the lower hybrid instability and the mode transition into the m = 1 macroscopic rotating structure after saturation of the linear phase is accompanied by an inverse energy cascade. In the nonlinear stage, pronounced spoke phenomena can occur when the heating of E θ × B electron flow channeled in the spoke front passage suffices to provide enhanced ionization.