Electron Storage Research Articles

Community ecological study on the reduction of soil antimony bioavailability by SRB-based remediation technologies

Sulfate-reducing bacteria (SRB) were effective in stabilizing Sb. However, the influence of electron donors and acceptors during SRB remediation, as well as the ecological principles involved, remained unclear. In this study, Desulfovibrio desulfuricans ATCC 7757 was utilized to stabilize soil Sb within microcosm. Humic acid (HA) or sodium sulfate (Na2SO4) were employed to enhance SRB capacity. The SRB+HA treatment exhibited the highest Sb stabilization rate, achieving 58.40%. Bacterial community analysis revealed that SRB altered soil bacterial diversity, community composition, and assembly processes, with homogeneous selection as the predominant assembly processes. When HA and Na2SO4 significantly modified the stimulated microbial community succession trajectories, shaped the taxonomic composition and interactions of the bacterial community, they showed converse effect in shaping bacterial community which were both helpful for promoting dissimilatory sulfate reduction. Na2SO4 facilitated SRB-mediated anaerobic reduction and promoted interactions between SRB and bacteria involved in nitrogen and sulfur cycling. The HA stimulated electron generation and storage, and enhanced the interactions between SRB and bacteria possessing heavy metal tolerance or carbohydrate degradation capabilities.

Decoupled Artificial Photosynthesis via a Catalysis-Redox Coupled COF||BiVO4 Photoelectrochemical Device.

Artificial photosynthesis is an attractive approach to direct fuel production from sunlight. However, the simultaneous O2 evolution reaction (OER) and CO2 reduction reaction (CDRR) present challenges for product separation and safety. Herein, we propose a strategy to temporally decouple artificial photosynthesis through photoelectrochemical energy storage. We utilized a covalent organic framework (DTCo-COF) with redox-active electron donors (-C-OH moieties) and catalytically active electron acceptors (cobalt-porphyrin) to enable reversible -C-OH/-C═O redox reaction and redox-promoted CO2-to-CO photoreduction. Integrating the COF photocathode with an OER photoanode in a photoelectrochemical device allows the effective storage of OER-generated electrons and protons by -C═O groups. These stored charges can be later employed for CDRR while regenerating -C═O to complete the loop, thus enabling on-demand and separate production of O2 or solar fuels. Our work sets the stage for advancements in decoupled artificial photosynthesis and the development of more efficient solar fuel production technologies.

Degradation of organic compounds in the dark using pre-illuminated Ag/TiO2 as a reusable Fenton-like material

Organic compounds were successfully degraded using silver-deposited titanium dioxide (Ag/TiO2) and hydrogen peroxide (H2O2). Electrons accumulate in Ag deposits on the surface of TiO2 under UV light (λ > 320 nm) illumination; therefore, pre-illuminated Ag/TiO2 activates H2O2 to hydroxyl radicals (•OH) and induces the degradation of 4-chlorophenol (4-CP) under dark conditions. In the presence of pre-illuminated Ag/TiO2 and H2O2 at [4-CP] = 50 μM, [H2O2] = 1 mM, and [pre-illuminated Ag(3.0 wt%)/TiO2] = 0.5 g/L, 64% of 4-CP was degraded after 90 min. The UV light-induced electron storage in Ag deposits and the electron transfer from the Ag deposits to H2O2 in the dark were confirmed by measuring the UV-visible absorption spectra of Ag/TiO2 before and after UV light illumination and the addition of H2O2. The verification of •OH production via a pre-illuminated Ag/TiO2-mediated Fenton reaction was performed using fluorescence spectroscopy, and coumarin was used as a chemical probe. Experiments conducted under various conditions suggest that the optimal conditions for maximum degradation are [H2O2] = 1.0 mM, [Ag/TiO2] = 0.5 g/L, and [Ag content] = 5.0 wt%. The H2O2 activation ability of the used Ag/TiO2 was completely restored through UV light illumination. Additionally, all the tested organic compounds, including 4-CP, 2-chlorophenol, 2,4-dimethylphenol, bisphenol A, sulfisoxazole, sulfamethoxazole, and furfuryl alcohol, were efficiently degraded in a suspension of pre-illuminated Ag/TiO2 and H2O2. Pre-illuminated Ag/TiO2 can be proposed as a practical Fenton-like material for water treatment owing to its high stability and reusability.

Modeling of intrinsic photon-stimulated desorption yields under readsorption effect

In synchrotron radiation and electron storage rings, photon-stimulated gas desorption is a major contributor to gas load, leading to vacuum degradation and compromising the stability and quality of the beamline. Therefore, it is imperative to investigate the underlying mechanisms of photon-stimulated gas desorption to enhance the reliability of the experiments. In this paper, a theoretical model for analyzing the process of photon-stimulated desorption is presented, and the equations are solved numerically by considering the evacuation, bulk diffusion, thermal outgassing, adsorption, and desorption of surface gas molecules. The modified model can predict the yield of H2 gas desorption induced by photon stimulation when synchrotron radiation is directed vertically onto various sample surfaces, utilizing the coupled multi-physics solution. The calculated results are consistent with the experimental measurements obtained from the Shanghai Synchrotron Radiation Facility. The results show that the photodesorption yield is related to the amount of surface-adsorbed molecules, which explains the observed decrease in the photodesorption yield with increasing accumulated photon dose. Furthermore, the study provides a theoretical approach to predicting the pressure evolution of photon-stimulated desorption.

Sulfonate-Based Triazine Multiple-Electron Anolyte for Aqueous Organic Flow Batteries.

A new highly soluble triazine derivative (SPr)34TpyTz showing three reversible redox processes with fast kinetics and high diffusion coefficients has been synthesized using an efficient, low-cost, and straightforward synthetic route. Concentrated single cell tests and DFT studies reveal a tendency of the reduced triazine species to form aggregates which could be avoided by tuning the supporting electrolyte concentration. Under the right conditions, (SPr)34TpyTz shows no capacity decay and good Coulombic, voltage, and energy efficiencies for the storage of two electrons. The storage of further electrons leads to a higher capacity decay and an increase of the electrolyte pH, suggesting the irreversible protonation of the generated species. So, a plausible mechanism has been proposed. A higher concentration of (SPr)34TpyTz shows slightly higher capacity decay and lower efficiencies due to the aggregate formation.

Manipulating electron extraction efficiency in microbial electrochemical carbon fixation via single-atom engineering

Microbial electrochemical carbon fixation can directly convert CO2 to renewable fuels, holding the promise of reducing greenhouse gas emissions. Whereas its further development is largely shadowed by the unclear correlation between the coordination environment and carbon-fixation biohybrids. Here, we report a single-atom engineering approach to control extracellular and interspecies charge exchange pathways for high electron efficiency via synergistic effects of Co-N4 coordination and microbiome biohybrids in the electro-methanogenesis system. Optimized carbon-fixation microbial community structures composed of electroactive methanogens and boosted extracellular polymeric substance-mediated charge exchange achieved a 21.49 times methane production rate of 568.7 mmol/m2/day (up to a maximum value of 1014 mmol/m2/day at −1.0 V vs. Ag/AgCl) and a 4.76 times faradic efficiency of 90.1% at −0.9 V vs. Ag/AgCl compared to control groups. Density functional theory calculations indicate that high Co-N/Co-C incorporation promotes the conversion of redox electron carriers for CO2 reduction, and Co-N/Co-C reduced the energy barrier of conductive substances and facilitated the electron storage at the bio/abiotic interface. The synergistic effect between Co-N4 structure and microbiome biohybrids facilitates an effective electron transfer, serving as reliable guiding principles for other microbial electrochemical systems to synthesize sustainable and value-added products.

Synthesis and Characterization of Titania Nanotubes with Au Nanoparticles

TiO2 nanotubes were prepared by hydrothermal synthesis and modified with different amounts of gold nanoparticles by deposition-precipitation with urea. The catalysts were characterized to determine the effect of the presence of Au nanoparticles on the physico-chemical characteristics of the materials and their electron storage capability. Raman spectroscopy revealed the transformation of the trititanate structure into the titania anatase domains upon gold deposition. This transformation was enhanced by an increase in Au loading and the thermal treatment of the materials. The size of Au nanoparticles increased upon the reduction treatment. The presence of Au nanoparticles produced a slight narrowing of the energy bandgap of the titania nanotubular material and had an important effect on its photoluminescence properties, important for some practical applications. Photoluminescence spectroscopy showed that the presence of Au nanoparticles on the surface of titania nanotubes significantly delayed electron-hole recombination and increased the ability of materials for charge separation. Superior performance of Au-containing titania nanotubes was illustrated by the evaluation of their photocatalytic activity. Au-containing titania nanotubes showed enhanced photocatalytic activity in the degradation of methylene blue dye in aqueous solutions upon UV irradiation compared to the pristine nanotubes and the titania Degussa P25.

Rapid degradation of organic pollutants by enhanced persulfate activation using CeO2-MnFe2O4 nanostructures: A polymetallic synergistic effect

Persulfate-based advanced oxidation processes (AOPs) have attracted considerable attention in the treatment of organic wastewater with high performance and long lifetime. The construction of efficient, environmentally-friend, and stable nanocatalysts has been recognized as a promising approach to activate persulfate. Herein, magnetic CeO2-MnFe2O4 nanomaterials fabricated via a simple sol-gel method were used for the first time to enhanced activate persulfate (PS) for the removal of the organic pollutant enrofloxacin (ENR). It was demonstrated that 97.2% of ENR (10 mg L−1) was efficiently degraded. 63.3% of TOC decreased within 35 min under a neutral solution (pH 6.81) in the PS+CeO2-0.2MnFe2O4 system using a catalyst dosage of 0.25 g L−1 and 0.18 mM PS. The magnetic CeO2-MnFe2O4 nanostructures maintained excellent recovery as well as recyclability ENR removal efficiency was 90% after recycling five times. EPR and quenching tests indicated that sulfate radicals (SO4•−) and hydroxyl radicals (•OH) significantly contributed to ENR removal. XPS analysis showed that the synergistic redox cycles of Ce3+/Ce4+, Mn2+/Mn3+, and Fe2+/Fe3+ are essential to activate PS for ENR degradation. DFT calculations also revealed that PS molecules preferred to adsorb to and dissociate on CeO2-MnFe2O4 surfaces rather than just CeO2 and MnFe2O4 surfaces. CeO2 plays a dual role in the charge transfer from CeO2-MnFe2O4 to PS molecules, i.e., both electron storage and donor. This work also provides a new interpretation to explain the activation mechanism of PS. The developed CeO2-MnFe2O4 nanostructures with rapid removal efficiency, high degradation efficiency and good recyclability may provide potential guidance for the design of polymetallic oxide nanocatalysts in PS-based AOPs.

Estimation of Absorbed Dose due to Gas Bremsstrahlung Based on Residual Gas in Electron Storage Rings

Gas bremsstrahlung, generated by the interaction between stored electrons and residual gas in electron storage rings, is an important radiation source for the shielding of synchrotron radiation (SR) facilities. In recent SR facilities, hydrogen was found dominant in the residual gas of the vacuum chambers of the electron storage rings, although air has been conventionally assumed as the bremsstrahlung target for the shielding designs of SR beamlines extended from the electron storage ring. To study the effect of residual gas composition on the dose rate outside shields, we calculated the intensity of gas bremsstrahlung based on the gas composition for both the air and the residual gas expected in the recent electron storage rings using an analytical formula and general-purpose Monte Carlo codes for particle transport calculations. The analytical shielding calculation with a realistic gas composition was found to well reproduce the energy spectra of gas bremsstrahlung simulated by the Monte Carlo codes. The correction factors between the air and the realistic gas compositions are applied to the conventional analytical formulas for dose estimation of secondary radiations generated by the interaction between the bremsstrahlung from air and beamline components.

Starvation combined with constant anode potential triggers intracellular electron storage in electro-active biofilms

The accumulation of electrons in the form of Extracellular Polymeric Substances (EPS) and poly-hydroxyalkanoates (PHA) has been studied in anaerobic processes by adjusting the access of microorganisms to the electron donor and final electron acceptor. In Bio-electrochemical systems (BESs), intermittent anode potential regimes have also recently been used to study electron storage in anodic electro-active biofilms (EABfs), but the effect of electron donor feeding mode on electron storage has not been explored. Therefore, in this study, the accumulation of electrons in the form of EPS and PHA was studied as a function of the operating conditions. EABfs were grown under both constant and intermittent anode potential regimes and fed with acetate (electron donor) continuously or in batch. Confocal Laser Scanning Microscopy (CLSM) and Fourier-Transform Infrared Spectroscopy (FTIR) were used to assess electron storage. The range of Coulombic efficiencies, from 25 to 82%, and the biomass yields, between 10 and 20%, indicate that storage could have been an alternative electron consuming process. From image processing, a 0.92 pixel ratio of poly-hydroxybutyrate (PHB) and amount of cells was found in the batch fed EABf grown under a constant anode potential. This storage was linked to the presence of living Geobacter and shows that energy gain and carbon source starvation were the triggers for intracellular electron storage. The highest EPS content (extracellular storage) was observed in the continuously fed EABf under an intermittent anode potential, showing that constant access to electron donor and intermittent access to the electron acceptor leads to the formation of EPS from the excess energy gained. Tailoring operating conditions can thus steer the microbial community and result in a trained EABf to perform a desired biological conversion, which can be beneficial for a more efficient and optimized BES.

Bi2MoO6 nanoflower-like microsphere photocatalyst modified by boron doped carbon quantum dots: Improving the photocatalytic degradation performance of BPA in all directions

Bi-based semiconductor photocatalyst represented by Bi2MoO6 (BMO) has obvious advantages in the degradation of bisphenol A (BPA), but three prominent problems that restrict the improvement of photocatalytic performance, namely, insufficient solar absorption, less active sites and serious photogenerated carrier recombination, need to be solved urgently. For this reason, we specially designed a simple structure of B-doped carbon quantum dots (BCQDs) modified BMO nanoflower-like microsphere composite to improve the photocatalytic performance of the system from the above three dimensions. The optimized BCQDs/BMO sample completely degraded BPA within 120 min under simulated sunlight, corresponding to an apparent constant of 0.03453 min−1, while the control sample of CQDs/BMO without B doping only degraded about 84 % of BPA within 160 min, with an apparent coefficient of 0.01138 min−1. Even after filtering out UV components below 400 nm, the degradation performance of the optimal composite catalyst did not decrease. The improved catalytic performance comes from the excellent up-conversion luminescence performance and good electron storage capacity of CQDs on the one hand, and the introduction of B on the other hand can adjust the surface structure of CQDs to generate more active sites and functional interfaces to further promote the catalytic reaction. Free radical trapping and electron spin resonance (ESR) tests have shown that·OH and·O2- are the main active substances in the degradation of BPA. The current BCQDs/BMO catalysts, despite their simple structure, can simultaneously improve the catalytic performance from the three important aspects mentioned above, which will guide the design of others semiconductor based photocatalysts.

Combined experimental and theoretical investigation on SONOS pFLASH switch

In this paper, a new push–pull pFLASH switch is designed and fabricated based on a 110 nm eFLASH process, which includes two 2 T-pFLASH transistors and one signal transmission transistor. The pFLASH transistors are programmed and erased by band-to-band tunneling-induced hot electron and Fowler–Nordheim tunneling to realize its ‘on/off’ function, and the current of the signal transmission transistor can be effectively tuned by the drain voltage of the 2 T-pFLASH. In order to clarify the degradation mechanism of the electronic properties, first principles calculations are performed from the atomic scale. Nitrogen vacancies have been proven to play a crucial role in nitrides. In addition, the effects of vacancies on the charge retention are investigated in terms of electronic structure. The nitrogen vacancies have proven to be detrimental to the electron storage by the simulated localization energies. Therefore, this study will provide a newly designed field-programmable gate array configuration unit, whose electrical mechanisms are revealed by theoretical simulations, which can also become the design foundation for future FLASH switches.

Giant enhancement of a long afterglow and optically stimulated luminescence phosphor BaCaSiO4: Eu2+ via Pr3+ codoping for optical data storage

The need for data storage is growing in modern society, and optical data storage (ODS) is considered one of the most promising storage techniques. However, significant challenges must be overcome, including improving the performance of volatile memory and expanding its storage capacity. In this study, we report a novel ortho-silicate phosphor, BaCaSiO4, doped with Eu2+, which exhibits sustained luminescence and optically stimulated luminescence (OSL). Following the Pr3+ co-doping, the long afterglow and OSL performance of BaCaSiO4: Eu2+ significantly improved owing to the substantial increase in trap density. Owing to numerous trapped and released electrons, the optical storage capacity of the OSL material significantly increased. As a proof-of-concept, ODS flexible media were fabricated using the obtained OSL material, based on which reversible information write-in and read-out were implemented using ultraviolet irradiation and optical/thermal stimulation, respectively. Furthermore, the OSL-based ODS mechanism was revealed through a comprehensive study of electron trapping, storage, and release kinetics.

Nanoscale spectromicroscopy with the full-field X-ray microscope at the BESSY II electron storage ring in the soft and tender X-ray range

In this paper, we give an overview of the nanoscale spectromicroscopy studies performed with the full-field X-ray microscope at the BESSY II electron storage ring. We do not consider spectromicroscopy studies performed with X-ray microscopes operated at other synchrotron sources. Such studies can be found in the literature. To our knowledge, the full-field X-ray microscope at the BESSY II storage ring is the first one operating with both a plane-grating-monochromator (PGM) beamline equipped with multi-layer optics for the tender X-ray range, as well as with standard optical elements for the soft X-ray range. We discuss how this instrument has been used in various published NEXAFS-TXM studies to probe low dimensional nanostructures. This research work paves the way for understanding electronic structures approaching the atomic scale, and will thereby help in the design of tailored functional systems.

A Mo doping WO3/CdZnS heterojunction photoelectrode for boosting electron storage capacity

Most of the photoelectrodes for photoelectrochemical cathodic protection (PECCP) technology reported at present cannot store electrons, leading to the inability to protect metals in the absence of light, which becomes the main defect that limits the practical application of PECCP. In this work, a Mo doping WO3/CdZnS heterojunction photoelectrode with electrons storage capability was prepared, by which the PECCP can be kept running in the absence of light. The result of theoretical calculation of density functional validates that Mo doping can introduce new doping levels into WO3, leading to modifications in the intrinsic electronic structure associated with increasing capacitance and conductivity. The compounding of CdZnS can not only broaden the light absorption threshold of the photoelectrode, but also charge the Mo-WO3. Besides, the construction of heterojunction also facilitates the oriented separation and migration of photogenerated carriers. The 0.3%Mo-WO3/CdZnS-2 composite photoelectrode with desirable capacity of electron storage can store the quantity of electric charge about 1.87 × 10−3 C after 100 s illumination, which is about 1.5 times of WO3/CdZnS-2 without Mo doping. In the meanwhile, the persistent PECCP performance in the absence of light was also prolonged from 481 s to 584 s.

Modulation of p- and n-Type Transitions in Co3- x Nix O4 Nanoparticles for Enhanced Supercapacitor Electrochemical Performance.

The efficient storage of electrons and the type of conduction in semiconductor materials are important factors in determining their electrochemical performance. However, the interaction between these two factors is often overlooked by researchers. In this study, the effects of Ni doping at Co3- x Nix O4 nanoparticles on the electronic storage form of the material and resulting changes in the conduction p/n-type are reported. Theoretical calculations demonstrate that n-type conduction with high effective mass of electrons contributes significantly to the redox reaction of electrode materials and is beneficial for improving electrochemical performance. The specific capacitance of Co3- x Nix O4 (x=0.67) electrode material is 10 times larger than that of Co3 O4 due to enhanced orbital hybridization caused by Ni atom doping. The findings provide new directions for exploring the mechanism of conductive type conversion of materials and offer insights beyond the traditional approach of considering doping content alone.

Revealing the formation process of extra capacitance in Fe3O4/Li batteries with the first-principles study

The formation of extra capacitance in Fe3O4/Li batteries can be comprehended by utilizing the in situ magnetometry method. Nevertheless, the precise mechanism behind this phenomenon remains elusive. In this study, we adopt Li x O8/Fe to investigate the formation process of extra capacitance in Fe3O4/Li batteries from a microscopic and quantitative viewpoint. The Fe0 atoms exhibit an enhanced capability to store extra charge during the Li16O8/Fe process, and has significantly contributes to the magnetization of the batteries. Furthermore, we provide an accurate description of the process from the storage of excess electrons to the formation of polymer films. The outcomes of our research could potentially facilitate better control over the generation of additional capacitance.

Increase and enrichment of active electrons by carbon dots induced to improve TiO2 photocatalytic hydrogen production activity

Recombination of photogenerated carriers severely reduces the efficiency of photocatalytic reactions. Herein, Bio-CDs/TiO2 were produced using the hydrothermal method to tightly load biomass-based carbon dots (Bio-CDs) onto the surface of TiO2via Ti-O-C bonds. Finite-difference time-domain (FDTD) simulations showed that the Bio-CDs act as electron storage pools in the Bio-CDs/TiO2, enhancing optical absorption and promoting the transfer and storage of photogenerated electrons from TiO2 to the Bio-CDs, and thus effectively inhibiting the recombination of electron-hole pairs. Photocatalytic hydrogen production by the Bio-CDs/TiO2 was significantly improved compared with that by pristine TiO2 (603.92 μmol h−1 g−1vs 94.18 μmol h−1 g−1) and, importantly, the Bio-CDs/TiO2 performed well over several cycles. Surprisingly, Bio-CDs/TiO2 also exhibits nice catalytic performance for hydrogen production under the combined action of photoelectricity, and its Tafel slope was significantly lower than that of pristine TiO2, which confirmed that the same research potential of Bio-CDs/TiO2 in the field of photoelectrocatalysis. This work introduces new ways to study the synergistic effects of multiple mechanisms (enhanced optical absorption, increased separation of photogenerated carriers and promotion of transfer and storage of photogenerated electrons) in the enhancement of photocatalytic and photoelectrocatalytic activity of semiconductors by carbon dots.

Lithium Ferrocyanide Catholyte for High‐Energy and Low‐cost Aqueous Redox Flow Batteries**

AbstractAqueous redox flow batteries (ARFBs) are a promising technology for grid‐scale energy storage, however, their commercial success relies on redox‐active materials (RAM) with high electron storage capacity and cost competitiveness. Herein, a redox‐active material lithium ferrocyanide (Li4[Fe(CN)6]) is designed. Li+ ions not only greatly boost the solubility of [Fe(CN)6]4− to 2.32 M at room temperature due to weak intermolecular interactions, but also improves the electrochemical performance of [Fe(CN)6]4−/3−. By coupling with Zn, ZIRFBs were built, and the capacity of the batteries was as high as 61.64 Ah L−1 (pH‐neutral) and 56.28 Ah L−1 (alkaline) at a [Fe(CN)6]4− concentration of 2.30 M and 2.10 M. These represent unprecedentedly high [Fe(CN)6]4− concentrations and battery energy densities reported to date. Moreover, benefiting from the low cost of Li4[Fe(CN)6], the overall chemical cost of alkaline ZIRFB is as low as $11 per kWh, which is one‐twentieth that of the state‐of‐the‐art VFB ($211.54 per kWh). This work breaks through the limitations of traditional electrolyte composition optimization and will strongly promote the development of economical [Fe(CN)6]4−/3−‐based RFBs in the future.

Lithium Ferrocyanide Catholyte for High-Energy and Low-cost Aqueous Redox Flow Batteries.

Aqueous redox flow batteries (ARFBs) are a promising technology for grid-scale energy storage, however, their commercial success relies on redox-active materials (RAM) with high electron storage capacity and cost competitiveness. Herein, a redox-active material lithium ferrocyanide (Li4 [Fe(CN)6 ]) is designed. Li+ ions not only greatly boost the solubility of [Fe(CN)6 ]4- to 2.32 M at room temperature due to weak intermolecular interactions, but also improves the electrochemical performance of [Fe(CN)6 ]4-/3- . By coupling with Zn, ZIRFBs were built, and the capacity of the batteries was as high as 61.64 Ah L-1 (pH-neutral) and 56.28 Ah L-1 (alkaline) at a [Fe(CN)6 ]4- concentration of 2.30 M and 2.10 M. These represent unprecedentedly high [Fe(CN)6 ]4- concentrations and battery energy densities reported to date. Moreover, benefiting from the low cost of Li4 [Fe(CN)6 ], the overall chemical cost of alkaline ZIRFB is as low as $11 per kWh, which is one-twentieth that of the state-of-the-art VFB ($211.54 per kWh). This work breaks through the limitations of traditional electrolyte composition optimization and will strongly promote the development of economical [Fe(CN)6 ]4-/3- -based RFBs in the future.