High Oxidation Potential Research Articles

The oxidative potential of airborne particulate matter in two urban areas of Chile: More than meets the eye

Oxidative potential (OP) has gained attention as a parameter that can reveal the ability of different properties of particulate matter (PM) to generate reactive oxygen species (ROS) as one single value. Moreover, OP is also believed to be a predictor of toxicity and hence the health effects of PM. This study evaluated the OP of PM10, PM2.5,and PM1.0samples using dithiothreitol assays in two cities of Chile (Santiago and Chillán). The results showed that the OP was different between cities, PM size fractions, and seasons. Additionally, OP was strongly correlated with certain metals and meteorological variables. Higher mass-normalized OP was observed during cold periods in Chillán and warm periods in Santiago and was associated with PM2.5 and PM1. On the other hand, volume-normalized OP was higher during winter in both cities and for PM10. Additionally, we compared the OP values to the Air Quality Index (AQI) scale and found cases of days that were classified as having “good” air quality (supposed to be less harmful to health) showing extremely high OP values that were similar to those on days that were classified as “unhealthy”. Based on these results,we suggest using the OP as a complementary measure to the PM mass concentration because it includes important new information related to PM properties and compositions that could help improvecurrent air quality management tools.

Accumulation of nitrite after reclaimed water recharge due to the disinfection byproduct chlorite

Due to its toxicity, the disinfection byproduct chlorite in drinking water is strictly regulated to be ≤ 1.0 mg/L, but in reclaimed, non-drinking water chlorite is unregulated and rarely considered. However, chlorite is cytotoxic and has a high oxidation potential. Therefore, as reclaimed water infiltrates soil and groundwater, it may alter the soil environment and microbial community, which may affect the degradation of organic matter and the transformation of the N element. In this study, the effects of reclaimed water containing chlorite on soil microorganisms were investigated by simulating subsurface infiltration. It was found that chlorite improved the conversion of nitrate nitrogen to nitrite nitrogen, but inhibited further conversion of nitrite nitrogen. The nitrite nitrogen in the effluent reached 4.61 mg/L when chlorite was present, while only 0.16 mg/L was found in the control system. The chlorite produced obvious oxidative stress reactions in cells, inhibited the EPSs production, in which the contents of polysaccharides and proteins reduced by nearly 41% and 62%, respectively. Besides, chlorite resulted in the enrichment of efflux resistance genes in the microbial community, mainly adeF and cmlB1. Self-protection against chlorite is achieved mainly using efflux pump related genes. Metagenomics data analysis showed that Delftia became the dominant genus when exposed to chlorite, with the greatest abundance at 17.9%. Chlorite also resulted in the upregulated expression of nar genes (by more than 149%) and downregulation of nir gene expression (by more than 62%). This study reveals the effects of the disinfection byproduct chlorite on a soil microecosystem, providing important information for the management and reuse of reclaimed water.

Investigation of the Effectiveness of Tetracycline Antibiotic Removal from Aqueous Solutions by Photo-Fenton Process using Biosynthesized Silver Nanoparticles

Introduction: Tetracycline is an antibiotic that is widely used around the world. Advanced oxidation processes are used for the degradation of resistant organic pollutants in aqueous solutions due to their high oxidation potential. This study aimed to estimate the performance of the ultraviolet rays/hydrogen peroxide/silver nanoparticles (UV/Ag/H2O2) in removing tetracycline antibiotics. Method: In this study, the degradation of tetracycline by the UV/Ag/H2O2 process was investigated under various conditions. The effects of different parameters, such as silver nanoparticles (1, 2, 4, and 6 mM), hydrogen peroxide concentration (10, 30, 50, 80, and 100 mM), pH (4, 7, and 10), and initial antibiotic concentration (15, 30, 45, and 60 mg/L) were investigated in the degradation of tetracycline. Finally, the antibacterial property of the synthesized nanoparticle was determined. Results: Under optimal conditions, within 90 min, the efficiency of tetracycline removal reached above 85% following pseudo-first-order kinetics. The obtained optimum conditions were as follows: tetracycline concentration (15 mg/L), oxidant concentration (80 mM), silver catalyst concentration (4 mM), and pH equal to 4. The size and morphological properties of nanoparticles were assessed by TEM, which showed that particles had a spherical shape with a diameter of about 1-50nm. The biosynthesized nanoparticle had high antibacterial properties. Conclusion: The results of this study showed that green synthesized silver nanoparticles with ultraviolet waves had great catalytic properties for oxidant activation and could also be used to inhibit and destroy resistant bacterial strains

Oxygen recovery from ozone generators by adsorption processes

As a triatomic allotrope of oxygen, ozone has many industrial and consumer applications because of its high oxidation potential and disinfectant properties. Most of the ozone is currently produced by corona discharge reactors using high-purity oxygen as the feed gas, where the conversion to ozone is typically 6−15 wt%. Given the high operating costs associated with the unreacted oxygen, it is essential to recover the oxygen for recycling to the ozone generator. This paper aims for the first time to design, simulate and assess cyclic adsorption processes for recovering oxygen from a mixture of ozone and oxygen (O3:O2 = 10:90 wt%) produced by a commercial ozone generator. A 2-bed, 2-step cycle was first investigated in which ozone is selectively adsorbed at high pressure and then desorbed by dry air used as a sweep gas. However, it was found that the O2 purity in the recycle stream was too low because of the nitrogen build up from air. Thus, two additional cycles, namely a 3-bed, 3-step cycle incorporating an oxygen purge step and a 3-bed, 4-step cycle incorporating a vacuum blowdown step, were evaluated with the purpose of removing nitrogen from the bed after the desorption step. Both adsorption cycles achieved a satisfactory O2 purity of 98+% in the recycle stream with a sacrifice of O2 recovery and an increase in energy consumption, respectively. As a result, the adsorption processes devised in this study could serve to significantly reduce the oxygen consumption in industrial ozone generators.

Green and efficient electrosynthesis of poly-3,4-ethylenedioxythiophene in aqueous micellar solution of zwitterionic surfactant

In this work, a biocompatible and biodegradable zwitterionic surfactant SB3-14 (n-tetradecyl-N, N-dimethyl-3-ammonio-1-propanesulfonate) was chosen to replace nonionic surfactant polyoxyethylene-10-laurylether (C12E10) to solubilize the poorly water-soluble monomer 3,4-ethylenedioxythiophene (EDOT), and in the micellar solution of SB3-14, the anodic polymerization of EDOT was studied to demonstrate the advantage of the zwitterionic surfactant over the nonionic surfactant. Compared with C12E10, SB3-14 is neither adsorbed on the glassy carbon electrode (GCE) over −0.2～1.0 V vs SCE, nor oxidized at the high oxidative polymerization potential for EDOT. These unique properties are favorable not only for the enhancement of the electropolymerization rate, but also for the improvement of the current efficiency. A comparative study on the electropolymerization modes, i.e., the constant potential mode and the pulsed potential mode, indicates that at high oxidative polymerization potential, the EDOT electropolymerization reaction is limited by the diffusion mass transfer of the electroactive monomer, and the growth rate of the polymer PEDOT can be significantly increased by prolonging the duration time of the pulse lower limit potential. At low oxidative polymerization potential, however, the EDOT polymerization reaction is basically controlled by the heterogeneous charge transfer process, and the electropolymerization modes have little effect on the growth rate of the PEDOT film. The XPS data of the PEDOT films demonstrate that SB3-14 is not doped (encapsulated) into the PEDOT film, and ClO4− is the only doping species. The doping level of the PEDOT film is determined by the oxidative polymerization potential and the electropolymerization mode. At high oxidative polymerization potential, the pulsed potential mode results in a PEDOT film with higher doping level than the constant potential mode does due to the periodic relaxation of the monomer concentration gradient as well as the full doping of the polymer in the duration time of the pulse lower limit potential. The above studies demonstrate that this new strategy is helpful for the green and efficient electrosynthesis of high quality PEDOT.

Revisiting the Reaction of IPr with Tritylium: An Alternative Mechanistic Pathway.

Despite a recent proposal on the mechanism of a single-electron transfer (SET) process between tritylium and 2,6-bis(diisopropylphenyl)imidazol-2-ylidene (IPr) based on evidence of transient IPr radical cation intermediate ([IPr]⋅+ ) formation, such oxidation is still contentious because of the high oxidation potential of N-heterocyclic carbenes. Our experimental analysis indicates that the appearance of deep purple color, previously considered to be from transient [IPr]⋅+ , originates from a zwitterionic intermediate (3 a), not a radical cation. Here, we propose an alternative mechanism for the reaction involving tritylium and IPr. This mechanism is noteworthy for explaining how [NHC-H]+ can be generated without the formation of transient [NHC]⋅+ , which has been frequently proposed as an intermediate for the reaction between NHC and oxidants. These results also show that a transient strong single-electron donor (3 a) could be generated by the alternative mechanism for oxidants using NHCs, which is a more feasible explanation for the reactivity of NHCs with oxidants.

Promoted electron transfer in Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction for efficient photo-Fenton oxidation of antibiotics

A Fe2+/Fe3+ co-doped BiVO4/Ag3PO4 S-scheme heterojunction catalyst was synthesized by a simple hydrothermal method and applied to achieve efficient photo-Fenton for antibiotics degradation (99.70 %). The co-doping of Fe3+/Fe2+ highlighted red shift of optical absorption edge (535–800 nm) and adjustable band structure of BiVO4/Ag3PO4. The collaborative system of photocatalytic and Fenton could maintain high catalytic activity and stability in the treat of simulated actual water and high efficiency within wide pH conditions (3–7). The degradation experiments were employed to show removal efficiency on tetracyclines and quinolones antibiotics including tetracycline (TC), ciprofloxacin (CIP), doxycycline (DO), levofloxacin (LEV), norfloxacin (NOR), and enrofloxacin (ENR). Mechanism exploration elaborated that the m-FBVO/APO composites with dominant Fe2+ preserved both high oxidation potential (<−0.33 eV vs NHE) and reduction potential (>2.45 eV vs NHE) through the constructed BiVO4/Ag3PO4 S-scheme heterojunction. Efficient e−/h+ pairs separation was further achieved through Fe3+/Fe2+ pairs cycling. And degradation pathway of TC was mainly investigated to verify its mineralization. This work provides a new sight towards catalytic mechanisms in heterogeneous photo-Fenton degradation systems.

Oxygen Vacancy Defect Engineering of Heterophase Junction TiO2: Interfacial/Surface Oxygen Vacancies Coadjust the Photocatalytic ROS Production

In this study, TiO2 samples are synthesized through two stages including hydrolysis and calcination. It is found that the addition of HCl in the hydrolysis stage could facilitate the formation of heterophase junction TiO2. By annealing at 300 °C in an argon atmosphere, interfacial oxygen vacancies (Vo) and surface Vo (distributed in the anatase phase) can be constructed in the heterophase junction TiO2. After photocatalytic experiments, it can be found that surface Vo and interface Vo have a synergistic effect in the production of photocatalytic reactive oxygen species (ROSs). Surface Vo can enrich O2 and transmit electrons to O2 on the surface of anatase. Therefore, the enriched O2 can be converted into •O2– and 1O2 easily. The interfacial Vo not only facilitate the electron transmission between the two phases but also change the electron transfer mode from I-scheme to Z-scheme. Thus, interfacial Vo make photogenerated electrons transfer to anatase and photogenerated holes leave in the rutile. These holes in the rutile part have high oxidation potential and can better oxidize H2O (or OH–) molecules to •OH. They can also oxidize •O2– to 1O2. This work promotes the further development of defect design and application in photocatalytic materials.

Homogeneous and Heterogeneous Catalytic Ozonation of Textile Wastewater: Application and Mechanism

This paper presents an overview of textile wastewater treatment by catalytic ozonation, highlighting the parameters of the process and accompanying mechanisms. Since more than 800,000 tons of dyes are produced annually and thousands of cubic meters of highly polluted textile wastewater have been emitted into the environment every day, this issue has become an environmental concern. Due to the high oxidative potential of ozone (2.08 V) and hydroxyl radical (2.80 V), the main reactive species in catalytic ozonation, the burdensome organic pollutants, including textile dyes, can be successfully decomposed. The paper shows the main groups of catalysts, emphasizing novel structural, nano-structured, and functionalized materials. The examples of catalytic ozonation in the industrial application for real textile wastewater were specially highlighted.

High Voltage and Capacity Dual-Ion Battery Using Acetonitrile-Aqueous Hybrid Electrolyte with Concentrated LiFSI-LiTFSI

Water-acetonitrile (AN) hybrid electrolyte with high concentration of bis(trifluoromethanesulfonyl) imide (LiTFSI) and Lithium bis(fluorosulfonyl) imide (LiFSI) (LiTFSI-LiFSI=3:1, molar ratio) supporting salts are studied for the high potential and large capacity rechargeable dual-ion battery. Water-acetonitrile hybrid electrolyte (WA) shows a wide electrochemical stability window of 3.1 V in 20 m aqueous electrolyte and 3.6 V in 20 m 9LiFSI-1LiTFSI in water: AN=1:3 molar ratio electrolyte. In particular, high oxidation potential, which can be assigned to the strong solvated ionic cluster formed between AN, water and LiTFSI-LiFSI supporting salts. The dual-ion battery is assembled using the graphitic carbon (KS6) and the activated carbon (AC) as cathode and anode, respectively, and 20 m LiTFSI-LiFSI in hybrid AN-water as electrolyte. It is found that the reasonably large capacity, coulombic efficiency and cycle stability were achieved. The KS6/AC cell shows 86 mAh g−1 at the initial cycle and 50 mAh g−1 at 100th cycle in a voltage range of 0–3.25 V, and the average coulombic efficiency of 85% is sustained over 200 cycles. The solvated structure of water to Li+ is strengthened by addition of AN from ATR-IR and NMR spectrums analysis and this change in the solvated structure is the main reason for the increased performance of the aqueous dual-ion battery.

Theoretical insights into the hydrogen oxidation reaction on single metal atoms anchored on the edge of MoS2 nanosheets

The application of alkaline fuel cells (AFCs) is seriously limited by the sluggish kinetics of the anodic hydrogen oxidation reaction (HOR), so it is urgent to develop efficient and stable non-noble metal HOR catalysts. In this work, we explored the HOR performance of single 3d metal atoms anchored at the edge of MoS2 nanosheets (MSA-MoS2, MSA = Fe, Co, and Ni) by the density functional theory calculations. The results suggested that the tetra-coordinated MSA and penta-coordinated meta-Mo atoms at the MoS2 edge could form the dual-active sites for the H* and OH* adsorption. The interaction between MSA and MoS2 supports can efficiently optimize the adsorption free energy of H* (ΔGH*) and OH* (ΔGOH*) by tuning the d band center of the activity sites. The calculated activation energy, rate constant, and exchange current density indicate that among the MSA-MoS2 catalysts, NiSA-MoS2 exhibits the highest activity for HOR, which is attributed to the optimal ΔGH* and ΔGOH*. Moreover, the thermodynamic and electrochemical stability of NiSA-MoS2 is confirmed by the strong formation energy and high oxidation potential. Therefore, NiSA-MoS2 can be considered as a promising candidate for HOR at the anode of AFCs.

Different reaction mechanisms of SO4•− and •OH with organic compound interpreted at molecular orbital level in Co(II)/peroxymonosulfate catalytic activation system

Hydroxyl radical (•OH) and sulfate radical (SO4•−) produced in advanced oxidation processes (AOPs) have been widely studied for organic contaminants degradation, however, the different radical characteristics and reaction mechanisms on organics degradation are still needed. In this study, a homogeneous Co(II)/peroxymonosulfate activation system was established for caffeine (CAF) degradation, and pH was controlled to regulate the radicals production. The different attack routes driven by SO4•− and •OH were deeply explored by transformation products (TPs) identification and theoretical calculations. Specifically, a method on dynamic electronic structure analysis of reactants (R), transition state (TS) and intermediates (IMs) during reaction was proposed, which was applied to elucidate the underlying mechanism of CAF oxidation by •OH and SO4•− at the molecular orbital level. In total, SO4•− is kinetically more likely to attack CAF than •OH due to its higher oxidation potential and electrophilicity index. Single electron transfer reaction (SET) is only favorable for SO4•−due to its higher electron affinity than •OH, while only •OH can react with CAF via hydrogen atom abstraction (HAA) route. Radical adduct formation (RAF) is the most favorable route for both •OH and SO4•− attack according to both kinetics and thermodynamics results. These findings can significantly promote the understanding on the degradation mechanism of organic pollutants driven by •OH and SO4•− in AOPs.

Life cycle assessment of novel biogeochemical cover versus conventional soil cover

The aim of this study is to evaluate the functional performance and environmental impacts of recently proposed biogeochemical cover (BGCC) system at a municipal solid waste landfill and compare with the conventional soil cover (SC) system. The functional performance of the cover systems was assessed through infiltration, methane emissions and slope stability analyses. In addition, life cycle assessment (LCA) was performed to evaluate the environmental impacts of the cover systems. The study also assessed the effect of various factors such as biochar manufacturing process, mode of transportation (fossil fuel powered vehicles versus electric powered vehicles), and transportation distance for raw materials supply on the environmental impacts. The results showed that the BGCC can significantly reduce the greenhouse gas emissions and global warming in comparison to the SC due to the use of biochar amended soil and basic oxygen furnace (BOF) slag. BGCC had 69 times more reduction in global warming impacts than SC which was attributed to the high methane oxidation potential of the biochar amended soil and carbon dioxide sequestration capacity of BOF slag. Moreover, BGCC had lesser environmental impacts than SC, mainly in the categories of eutrophication, carcinogens, non-carcinogens, respiratory effects, and ecotoxicity. Reducing transportation distance for biochar supply led to further reduction of the environmental impacts associated with the BGCC. For example, reducing the biochar procurement distance from 300 km to 100 km reduced the impacts from smog, acidification, eutrophication, and fossil fuel depletion by 14%, 13%, 5% and 14%, respectively. In addition, switching the vehicle from diesel powered to electric powered for transportation of raw materials led to significant reduction in fossil fuel depletion, smog, acidification and ecotoxicity in both BGCC and SC. For example, the fossil fuel depletion reduced by 97% and 39% in BGCC and SC, respectively by switching the fuel source. In addition, BGCC had overall positive impact on the human health and ecosystem whereas SC showed potential damage to human health. Overall, BGCC system proves to be an environmentally sustainable alternative to landfill cover system with significant potential for mitigation of greenhouse gases and odor from MSW landfills.

State-of-the-Art on the Sulfate Radical-Advanced Oxidation Coupled with Nanomaterials: Biological and Environmental Applications.

Sulfate radicals (SO4-·) play important biological roles in biomedical and environmental engineering, such as antimicrobial, antitumor, and disinfection. Compared with other common free radicals, it has the advantages of a longer half-life and higher oxidation potential, which could bring unexpected effects. These properties have prompted researchers to make great contributions to biology and environmental engineering by exploiting their properties. Peroxymonosulfate (PMS) and peroxydisulfate (PDS) are the main raw materials for SO4-· formation. Due to the remarkable progress in nanotechnology, a large number of nanomaterials have been explored that can efficiently activate PMS/PDS, which have been used to generate SO4-· for biological applications. Based on the superior properties and application potential of SO4-·, it is of great significance to review its chemical mechanism, biological effect, and application field. Therefore, in this review, we summarize the latest design of nanomaterials that can effectually activate PMS/PDS to create SO4-·, including metal-based nanomaterials, metal-free nanomaterials, and nanocomposites. Furthermore, we discuss the underlying mechanism of the activation of PMS/PDS using these nanomaterials and the application of SO4-· in the fields of environmental remediation and biomedicine, liberating the application potential of SO4-·. Finally, this review provides the existing problems and prospects of nanomaterials being used to generate SO4-· in the future, providing new ideas and possibilities for the development of biomedicine and environmental remediation.

A cascade protection strategy from cathode to anode with high air stability for ultralong life Li-air batteries in ambient conditions

Li-air batteries (LABs) possess an ultrahigh theoretical energy density exceeding 3500 Wh/kg, but to date, only pure O2 is applied as the operating environment in most literature, which seriously limits its application potential. Under ambient air, water molecules would easily induce Li anode pulverization and electrolyte decomposition, which eventually lead to battery failure. Apart from the above issues, water will also cause the discharge product to convert into LiOH, which would decompose at a higher oxidation potential. Herein, to enable aprotic LABs to work in an actual air environment, a cascade cathode to anode protection strategy is developed. Generally, a highly water repulsive and controllable passivation layer on the Li surface is elaborated by D4, D4H and MM interaction, which serves as the first shield to prevent Li reaction with permeated water. Meanwhile, the second shield is constructed at the cathode side with non-polar D4 molecules to tolerate the penetration of polar water. As a consequence, the LABs exhibit extralong cycling life up to 375 cycles (1400 h) in ambient conditions with relative humidity (RH) of 60% after constructing the cascade protection from cathode to anode. The cycle life is 12 times higher than the pristine unprotected LABs. To the best of our knowledge, this is the first LABs with a cycle life exceeding 1400 h in an air environment of 60% RH, which provides new insight into LABs' practicability. As an example, the decorative lamps with the above LABs continuously illuminate up to 100 h in ambient conditions.

Novel MoSSe/Bi2WO6 S-scheme heterojunction photocatalysts for significantly improved photoelectrochemical and photocatalytic performance

Two-dimensional MoSSe nanoplates demonstrate low internal resistance and outstanding reduction potential, while Bi2WO6 nanoparticles exhibit zero-dimensional appearance and high oxidation potential. Herein, novel MoSSe/Bi2WO6 step-scheme (S-scheme) heterojunction photocatalysts (MSSB) were prepared to combine the properties of those two materials. These catalysts were confirmed to have lower internal resistance (as low as 0.07 kΩ), and higher carriers’ separation efficiency due to the well-contacted two-dimensional/zero-dimensional structure. More importantly, the heterojunction catalysts displayed both good oxidation and reduction performance which have been confirmed by the conducted catalytic tests. With an optimized Bi2WO6 loading ratio, degradation rates (k) and photocurrent density of the MSSB2 sample were 2.09, and 8.31 times more than that of MoSSe, as well as 1.77, and 26.27 times more than that of Bi2WO6. Active species (superoxide radical •O2− and hydroxyl radical •OH) were detected by the electron spin resonance tool which could infer that a S-scheme heterojunction has already constructed between the Bi2WO6 and MoSSe. Driven by the MoSSe and band edge bending, the e– on the conduction band of Bi2WO6 readily slid toward MoSSe and recombines with the h+ on the valence band of MoSSe, while retaining the powerful e– and h+ with high redox potential on the CB of MoSSe and VB of Bi2WO6. This work further provided a novel strategy for developing S-scheme nano-heterojunction catalysts and revealed their prospects in photoelectrochemistry and photocatalysis.

Bayesian optimization of dynamic Ce(III) electrooxidation

AbstractCerium(III/IV) is a redox couple with promising applications in redox flow batteries and redox‐mediated water electrolyzers, but due to its high oxidation potential, parasitic oxygen evolution can occur and decrease the Faradaic efficiency (FE) of the oxidation reaction. Dynamic potential dosing can help balance the transport limitations and the electrooxidation rates, allowing for control over the cerium(III) concentration near the electrode, enhancing FE. Due to the large number of possible pulsing operating conditions, Bayesian optimization (BO) was used to rapidly identify the optimal potential pulses. With an active pulse voltage of 2.5 V vs. Ag/AgCl, the maximum FE achieved was 0.91 (active pulse time = 5 ms, resting pulse time = 136 ms), underscoring the need for long inactive times for cerium(III) diffusion to the electrode. Furthermore, a multiobjective BO was performed to identify optimal trade‐offs between FE and the partial current density to achieve improvements over constant current operation.

Application of single-atom Fe implanted N-doped carbon material as co-catalyst in the Fenton-like reaction and exploration of its enhanced activity

Due to slow recovery of Fe2+ and a narrow pH range of the Fenton and Fenton-like reactions, a single-atom Fe implanted N-doped carbon material (rGO@NC/SA-Fe) was used as the co-catalyst in the Fe3+/H2O2 system in this paper. This material greatly accelerated the Fe3+/Fe2+ cycle and thus promoted Rhodamine B (RhB) degradation. RhB was almost completely removed even at pH= 7. A systematic comparison was conducted between rGO@NC/SA-Fe and rGO@NC (without Fe). The results proved the vital importance of Fe single atoms, which not only improved the electron conductivity of rGO@NC/SA-Fe, but also promoted the combination of carbon materials and Fe3+ with a higher oxidation potential. Moreover, the enhanced H2O2 adsorption on single-atom Fe sites facilitated the participation of H2O2 in the reaction. In addition, rGO@NC/SA-Fe exhibits excellent catalytic activity in various water bodies. The material still possessed good re-usability and stability after five catalytic cycles, which demonstrated its great application potential in wastewater treatment.

Preparation and solar thermochemical properties analysis of NiFe2O4@SiC/ @Si3N4 for high-performance CO2-splitting

The solar-driven thermochemical CO2-to-CO conversion is an effective way to achieve the mission of carbon peaking and carbon neutrality. However, synthesizing porous reacting materials with excellent thermal stability, hardness and long-term cyclic stability, oxygen exchange capacity, and higher CO2-to-CO conversion are the most important challenges associated with the thermochemical CO2-splitting approach and technological upscaling to large-scale applications. This study presented the development of NiFe2O4 oxygen carriers, the synthesis method of SiC and Si3N4 supports, and solar-to-fuel processing of the newly prepared materials through CO2-splitting under a highly concentrated solar radiative heat flux. The newly synthesized NiFe2O4@SiC porous redox material resulted in higher solar energy absorption and CO2 conversion capability with an instantaneous CO production of 410 μmol/g and direct CO2-to-CO conversion rate of 18.1 % at 1073–1273 K reaction temperature. The media composite of NiFe2O4@SiC exhibited high-temperature thermal changes, good thermochemical reaction stability, and a higher CO production rate through six redox cycles compared to NiFe2O4@Si3N4 porous reacting material. The high oxidation potential and remarkably solar radiative heat flux absorption and thermochemical CO2-splitting capacities of the newly developed materials were demonstrated through experimental analysis. The synergistic effect of the oxygen carriers (NiFe2O4) and substrate materials including SiC and Si3N4 skeletons for CO2-splitting is highlighted. This study provided comprehensive and novel experimental insights that can be used as guidance for theoretical research and application in CO2 conversion into high-value-added energy products.

(Digital Presentation) A Polymerized-Ionic-Liquid-Based Polymer Electrolyte for >4 V Class Solid-State Lithium Metal Batteries

Polymer solid electrolytes for solid-state batteries typically suffer from low ionic conductivity and low oxidative stability. We report a polymer electrolyte based on a polymerized ionic liquid and an ionic liquid plasticizer offering simultaneously a high room-temperature ionic conductivity of 0.8 mS cm-1 and a high oxidative stability > 5.0 V vs Li+/Li. The electrolyte is compatible with lithium metal, exhibits high thermal stability up to 300 °C, is non-flammable upon direct flame exposure, shows decent lithium-ion transference number of 0.44, and possesses a low gravimetric density of only 1.6 g cm-3, important when targeting batteries with high gravimetric energy density. In symmetric lithium metal cells, the electrolyte enables stable lithium plating and stripping at 0.1 mA cm−2 with a capacity of 1 mAh cm−2 per half cycle for over 1700 h at 25 °C. Cells with a lithium metal anode cycled against a state-of-the-art high-energy uncoated layered LiNi0.8Mn0.1Co0.1O2cathode achieve an initial capacity of 162 mA h g-1 and a capacity retention of 72% after 600 cycles to an upper cut-off voltage of 4.4 V at 0.1 mA cm-2 and 25 °C. Cells with a high-voltage spinel LiMn1.5Ni0.5O4 cathode reach an initial capacity of 132 mAh g-1 and a capacity retention of 76% after 300 cycles to an upper cut-off voltage of 5 V at 0.1 mA cm-2 and 25 °C, confirming the high oxidative stability and technological potential of this electrolyte for high-voltage solid-state lithium metal batteries.