Oxygen Functionalities Research Articles

The allylic oxidation of tigliane esters

As part of a study on the structure-activity relationships of the anticancer agent tigilanol tiglate (EBC-46, 2), the allylic oxidation of phorbol triacetate (1c) and of the acetonide of its 3αH-dihydroderivative (5) was investigated. The aim was to introduce an oxygen function at C-5 en route to point-like analogues of 2, but functionalization of C-10 was instead observed. This was followed by oxidative fragmentation of ring B to the 9,10-secotigliane derivative 6 and oxidation of the endocyclic Δ6 double bond to the C-6/C-10 oxygen bridged 7-oxotigliane 7. Despite the over-functionalization of ring B, these observations suggest the possibility to modify positions overlooked in the oxidase phase of tigliane biosynthesis and explore novel areas of the phorbol chemical space.

Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals.

With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.

The effect of augmentation of biochar and hydrochar in anaerobic digestion of a model substrate

The augmentation of biochar produced at 450 and 600–650 °C and hydrochar produced at 250 °C has been investigated using biochemical methane potential experiments of cellulose. The feedstocks used for the char production included the lignocellulosic (oak wood), macroalgae (Fucus serratus) and aquatic plant (water hyacinth). Biomethane production was improved with the addition of lower-temperature biochars from oak wood (285 mL CH4/g VS) and water hyacinth (294 mL CH4/g VS), corresponding to 7 and 11% more than the control. The addition of these two biochars increased the methane production rate of 2.4 and 2.3 times the control, respectively. Higher temperature biochars showed no difference. Conversely, all hydrochars and macroalgae biochars augmentation reduced methane generation by 57–86 %. The chemical and structural composition of each of the chars differed significantly. Surface oxygen functionality appears to be the most important property of the biochars that improved digestion performance.

Energy efficient functionalization of graphene for tunable fluorescence

Multifunctionality of Carbon-Based Nano Materials, Graphene in particular is gaining more relevance in their diversified applications. Today, the fabrication of luminescent graphene materials is significant for the field of bioimaging of healthy and malignant cells due to their biocompatible tunable fluorescence. In this aspect there is a need for a simple, energy efficient process for the introduction of hetero atoms of Oxygen and Sulphur into the graphene structure to explore the enhancement of fluorescence. The present study aims at the optimization of processing temperature and other experimental parameters for doping hetero atoms of Oxygen and Sulphur in the graphene structure for tuning their luminescence properties. The method involved hydrothermal carbonization of simple precursor of glucose at lower temperatures of 180°C and 220°C and alkaline pH followed by the analytical characterization of the product samples. The introduction of hetero atoms, the presence of sp2 Carbon, band gap energy, microstructure along with layer structureswere ascertained in the as-synthesized graphene samples. The influence of processing temperature, oxygen functionality and defect structures upon emission wavelength range of graphene in the visible region was well correlated. Ultimately, the study provided the fundamental aspects of fabricating graphene structures suitable for tunable fluorescence of graphene aimed at bio imaging technique.

Pulmonary Function Status After Implementing Chest Physiotherapy for Extubated Cardiothoracic Surgery Patients

AbstractChest physiotherapy considered basic nursing interventions for patients undergoing cardiothoracic surgery to improve breathing efficiency, oxygenation and pulmonary functions. Aim of the study: to evaluate the pulmonary function status after implementing chest physiotherapy for extubated cardiothoracic surgery patients. Design: Quasi experimental research design (study and control) was used in this study. Setting: cardiothoracic intensive care unit and cardiothoracic department at cardiothoracic hospital that belongs to Minia University Hospitals, Egypt. Two tools: 1. Socio demographic and medical Assessment sheet. 2. Oxygenation level assessment sheet. Results: mean age of study and control groups were (38.4±5.4) & (37.2±4.8) year respectively. (40%) from the study group suffered myocardial infarction and did coronary angioplasty, (43.3%) of the control suffered coronary artery stenosis (33.3%) among them did coronary angioplasty. Regarding breathing sound, and pulmonary function test there is statistical significant difference between both groups presented by p value <0.05, also there were significant difference between both groups related to all items of the arterial blood gases test presented by P value with (.031*, .004**, .020*, .013* & .003**). Conclusion: This study concluded that chest physiotherapy had a positive effect on patient's pulmonary function status which reflected on the patients outcomes post cardiothoracic surgery. Recommendations: All cardiac surgery patients should receive an explanation about chest physiotherapy before their operations.

Solid-phase extraction cartridges with multi-walled carbon nanotubes and effect of the oxygen functionalities on the recovery efficiency of organic micropollutants

Pristine and functionalized multi-walled carbon nanotubes (MWCNTs) were investigated as adsorbent materials inside solid-phase extraction (SPE) cartridges for extraction and preconcentration of 8 EU-relevant organic micropollutants (with different pKa and polarity) before chromatographic analysis of surface water. The recoveries obtained were > 60% for 5/8 target pollutants (acetamiprid, atrazine, carbamazepine, diclofenac, and isoproturon) using a low amount of this reusable adsorbent (50 mg) and an eco-friendly solvent (ethanol) for both conditioning and elution steps. The introduction of oxygenated surface groups in the carbon nanotubes by using a controlled HNO3 hydrothermal oxidation method, considerably improved the recoveries obtained for PFOS (perfluorooctanesulfonic acid) and methiocarb, which was ascribed to the hydrogen bond adsorption mechanism, but decreased those observed for the pesticide acetamiprid and for two pharmaceuticals (carbamazepine and diclofenac), suggesting π–π dispersive interactions. Moreover, a good correlation was found between the recovery obtained for methiocarb and the amount of oxygenated surface groups on functionalized MWCNTs, which was mainly attributed to the increase of phenols and carbonyl and quinone groups. Thus, the HNO3 hydrothermal oxidation method can be used to finely tune the surface chemistry (and texture) of MWCNTs according to the specific micropollutants to be extracted and quantified in real water samples.

Evaluation of a quaternized polyethersulfone membrane enhanced with amine functionalized carbon nanotubes for forward osmosis application

Multiwall carbon nanotubes (CNTs) were quaternized with trimethylamine to form an anionic conductive CNTS (QCNTs) then blended with quaternized polyethersulfone membrane (QPES) by phase invasion method to obtain a composite membrane with higher permeation, improved rejection and enhanced antifouling properties for forward osmosis application. The membranes and QCNTs were characterized using SEM, TGA, NMR, Raman and FTIR. The fabricated composite membranes showed that addition of QCNTs can improve membrane basic properties when compared to commercial polyethersulfone membranes. This observed improvement could be attributed to the incorporated oxygen and amine functionalities in the CNTs. The 0.1 wt % QCNTs showed a contact angle of 64, reverse solute flux of 7.4 and 6.2 Lm-2h-1 for NaCl and MgSO4 respectively compared to an original pure water flux of 8.058 Lm-2h-1. Humic acid was used as a foulant, when the composited was fouled using humic acid, the 0.1wt.% QCNTs showed a reverse solute flux of 5.7 and 5.0 Lm-2h-1 respectively at room temperature.

Role of Renal Replacement Therapy During the Peri-Transplant Period of Heart Transplantation.

BackgroundHeart transplantation (HT) is the most useful treatment modality for heart failure. Although several studies have reported the impact of acute kidney injury (AKI) on clinical outcomes after transplantation, little is known about the impact of peri-transplant renal replacement therapy (RRT) on clinical outcomes. We compared the clinical outcomes according to RRT use status among patients with AKI during the peri-transplant period.Material/MethodsThe medical records of 21 patients who underwent HT from January 2006 to May 2019 were reviewed. We assessed the heart failure cause, comorbidities, immunosuppressant type, requirement for extracorporeal membrane oxygenation, AKI incidence, and cardiac and renal functions over time. The patients were divided into 3 groups: those without AKI (non-AKI group, n=6), those who underwent perioperative RRT (RRT group, n=10), and those who did not undergo RRT (non-RRT group, n=5).ResultsThe most common cause of HT was dilated cardiomyopathy (52.4%). Fifteen patients (71.4%) experienced AKI during the peri-transplant period. Among them, 9 (90%) in the RRT group underwent continuous RRT and only 1 (10%) underwent intermittent hemodialysis. Until 6 months after HT, the renal function of the RRT group was worse than that of the non-RRT group (estimated glomerular filtration rate 44.2 vs. 69.2 mL/min/1.73 m2, P=0.015), but the differences dissipated by 9 months. Finally, all patients, even in the RRT group, withdrew from dialysis.ConclusionsRRT during the peri-transplant period in HT may be a good bridge therapy for renal function recovery in patients with cardiorenal AKI.

A New Glass Forming Electrolyte Based on Lithium Glycerolate

The study of the interplay between structure and conductivity in lithium-conducting electrolytes is a pivotal point for the development of future secondary batteries [1]. The use of Glycerol as a low molecular weight component in electrolytes is particularly interesting due to its glass-forming behavior and low glass transition temperature (-78.5°C). In addition, a high flexibility of the alkyl backbone chain and the well-known capability of oxygen functionalities to coordinate lithium cations make Glycerol very appealing as ion-conducting media as well as building block to obtain hybrid polymer electrolytes [2].On this basis a family of eleven electrolytes based on Lithium Glycerolate with general formula C3H8-xO3Lix, where 0 ≤ x ≤ 1, is prepared and investigated [3]. In these electrolytes the Glycerolate (C3H8-xO3 x-) component acts as a large and flexible macro-anion which is able to provide a high single-ion conductivity to the material (8.36∙10-5 S∙cm-1 at 20°C and 1.55∙10-2 S∙cm-1 at 150°C for x = 0.25).Finally, the Glycerol∙∙∙Li+ interactions in these electrolytes are studied on T and x, with a particular reference to the detection of: a) macro-anion coordination sites; and b) the secondary structure of Glycerol chains. Insights on the long-range charge transfer mechanism and Glycerol relaxation events are also discussed.These studies are carried out by Inductively-Coupled Plasma Atomic Emission Spectroscopy, IR and Raman spectroscopies, DSC, TGA, and Broadband Electrical Spectroscopy.

Analytical modeling of graphene oxide based memristor

Nowadays, carbon–based materials like graphene and its derivatives consume great nano-technological applications worldwide. Graphene, due to its attractive properties such as its unusual charge transport, mechanical and thermal capabilities, is in the nano-scaling research spotlight. Additionally, to overcome the scaling limitations of large-scale charge-storage-based memories, the Memristor is focused upon as a nonvolatile memory. In the present work, the modeling of a Memristor based on graphene oxide as an active layer is considered. The drift-diffusion formalism as an electron transport mechanism, derived from ion immigration, is explored. It is concluded that by increasing the voltage between two metalelectrodes, the carrier concentration is increased, and the carrier mobility on the sandwiched layer (graphene oxide) is decreased. The conductive path by the redox of graphene oxide (GO) atoms, due to the conversion of sp3 to sp2 oxygen functionalities, is formed, which can be modeled by degenerate mode (the low resistance switching or ON state). This path is ruptured by decreasing the voltage into the reset voltage, which is modeled by the non-degenerate mode (the high resistance switching or OFF state). Finally, the model in comparison with the experimental data numerically is simulated, and acceptable results for metal and graphene–like path formation are observed.

Role of oxygen functionalities of GO in corrosion protection of metallic Fe

We demonstrated the mechanism that makes Graphene Oxide (GO) a superior material for corrosion protection over reduced graphene oxide (rGO) and nitrogen doped reduced graphene oxide (N-rGO). According to the results of our electrochemical study, supported by a host of characterization methods and density functional theory (DFT) based calculations, reduction of GO to synthesize rGO or doping of foreign heteroatoms like nitrogen to synthesize N-rGO, exposes and/or creates the defects/pores on the basal carbon plane of GO. Through these defects/pores of rGO and N-rGO, the corrodants react with the metal-surface and corrode it. A subnanometric layer of GO adhered to carbonyl iron (CI) surface through grafting by a thin Glycine (Gly) layer, repels the corrodants and shows robust corrosion protection performance in 1 M KCl solution, over a similar layer of rGO or N-rGO. Hence, our work demonstrate that a coating of GO on metallic Fe surface, grafted via a thin glycine layer, is the economical solution and has the robust performance for its direct industrial application for corrosion protection.

Regulation of redox processes in biological systems with the participation of the Keap1/Nrf2/ARE signaling pathway, biogenic selenium nanoparticles as Nrf2 activators

The article is devoted to the mechanisms of regulation of redox processes in cells, a review of the Keap1 / Nrf2 / ARE redox-sensitive signaling system as a fundamental pathway that plays a key role in maintaining cellular redox homeostasis under stressful, inflammatory, carcinogenic and proapoptotic conditions. The structure of the cysteine-rich repressor protein Keap1, which is responsible for sensory perception of electrophiles and reactive oxygen species, the structure and functions of the transcription factor Nrf2, mechanisms of Nrf2 activation through the Keap1 / Nrf2 / ARE signaling system, which regulates the transcription and expression of cellular cytoprotective and antioxidant proteins, are described. Published data on the specificity of the interaction of the components of this cellular signaling pathway, the mechanisms of Keap1 dependent and independent adaptive response to the action of inductors, the role of biogenic selenium nanoparticles synthesized by green chemistry with the participation of bacteria in these processes are analyzed; features of Nrf2 induction depending on the type of bacteria and the stabilizing shell. It has been shown that biogenic selenium nanoparticles (BNSe), synthesized by different types of bacteria, activate the transcription factor Nrf2 using the Keap1-independent activation pathway through mitogen-protein kinases (MAPK): p38, ERK1 / 2 and AKT-mediated phosphorylation of Nrf2, protect the intestinal epithelial barrier function from the effects of oxidative damage, normalize mitochondrial function. A detailed understanding of thiol-dependent and independent redox signaling mechanisms under physiological and pathological conditions will lead to a deeper understanding of the redox component in human and animal diseases. The use of biogenic nanoselen, synthesized with the participation of various bacterial species, has been demonstrated to activate the Keap1 / Nrf2 / ARE signaling pathway, which may be of practical interest as a therapeutic target for many redox-mediated diseases.

The assessment of lung function and residual hypoxemia after balloon pulmonary angioplasty for patients with chronic thromboembolic hypertension

Abstract Background It has been reported that balloon pulmonary angioplasty (BPA) could dramatically improve hemodynamics in patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients have shown poor response in oxygenation and lung function even after BPA. The aim of our study was to evaluate the efficacy of BPA using clinical indicators and to investigate lung function and residual hypoxemia. Method Consecutive 103 patients who underwent BPA from September 2011 to August 2018 were enrolled. We evaluated hemodynamics with right heart catheterization, respiratory function test, arterial blood gas examination, and exercise capacity with 6 minute-walk-distance (6MWD). Result At the median 12-month follow-up after the final BPA session, following examination findings were significantly improved. Mean pulmonary artery pressure (39.0±8.2mmHg, 23.2±8.4mmHg, p&amp;lt;0.001), Pulmonary vascular resistance (782±378 dynes / sec / cm-5, 331±187 dynes / sec / cm-5, p&amp;lt;0.001), 6 MWD (310±94 m, 363±119 m, p&amp;lt;0.001), PaO2 (63.1±15.8 mmHg, 68.5±13.6 mmHg, p=0.044),%VC (88.5±17.1, 91±16.3, p=0.036). However, the following examination findings did not improve after BPA. Oxygen desaturation during 6MWD test (−11.9±6.3, 12±7.9, p=0.65), %DLCO (64.2 17.1, 61.3 16.8, p=0.147). Conclusion BPA could dramatically improve hemodynamics and exercise tolerance. However, arterial oxygenation was not normalized after BPA. Moreover, oxygen desaturation in exercise, and %DLCO were almost unchanged. These observations might suggest the remaining arteriopathy in capillary level of pulmonary artery, but further research is needed. Funding Acknowledgement Type of funding source: None

Full recycling of spent lithium ion batteries with production of core-shell nanowires//exfoliated graphite asymmetric supercapacitor

Electrodic powder coming from real waste spent lithium ion batteries was employed as raw material for the production of asymmetric supercapacitor allowing the full recycling of the electrodic powder components. A novel process is reported which produces an asymmetric supercapacitor through the complete recycling of end-of-life lithium ion batteries. The electrodic powder recovered by industrial scale mechanical treatment of spent batteries was leached and the dissolved metals were precipitated as mixed metals carbonates. Nanowires battery-type positive electrodes were produced by electrodeposition into nanoporous alumina templates from the electrolytic baths prepared by dissolution of the precipitated carbonates. The impact of the different metals contained in the electrodic powder was evaluated by benchmarking the electrochemical performances of the recovered nanowires-based electrodes against electrodes produced by using high-purity salts. Presence of inactive Cu in the nanowires lowered the final capacitance of the electrodes while Ni showed a synergistic effect with cobalt providing a higher capacitance with respect to synthetic Co electrodes. The carbonaceous solid recovered after leaching was in-depth characterized and tested as negative electrode. Both the chemical and electrochemical characterization indicate that the recovered graphite is characterized by the presence of oxygen functionalities introduced by the leaching treatment. This has led to the obtainment of a recovered graphite characterized by an XPS C/O ratio, Raman spectrum and morphology close to literature reports for reduced graphene oxide. The asymmetric supercapacitor assembled using the recovered nanowires-based positive electrodes and graphite as negative electrodes has shown a specific capacitance of 42 F g −1 , computed including the whole weight of the positive electrode and recovered graphite, providing a maximum energy density of ~9 Wh kg −1 and a power density of 416 W kg −1 at 2.5 mA cm −2 .

Unraveling the mechanisms of lead adsorption and ageing process on high‐temperature biochar

AbstractBACKGROUNDThe synthesis gas or hydrogen‐rich gas, at longer residence times and higher temperatures, is frequently the target of pyrolysis biomass. Biochars obtained at such conditions contain less functional groups but they are more effective for longer‐term soil C storage. The aim of this study was to elucidate the adsorption mechanisms and the effect of the ageing process on high‐temperature biochar towards lead adsorption. The biochars under study were produced from the pyrolysis of almond wood and olive tree pruning.RESULTSThe almond hardwood biochar was the most susceptible to the oxidation process. This biochar exhibited higher carbon loss than the olive biochar, 22.07% and 11.76%, respectively. The adsorption process was better described by the Langmuir model and pseudo‐second order kinetics. The maximum adsorption capacity decreased from 40.3 to 24.8 mg g–1 after the oxidation process for almond‐derived biochar and remained unchanged for the olive‐biochar. Analyses demonstrated that 67% of the adsorbed Pb2+ was removed through complexation by oxygen functionalities and phosphorous compounds. After the oxidation process, this fraction accounted for only 45% of the adsorbed Pb2+, ion exchange and cation‐π being the most prominent mechanisms for the adsorption.CONCLUSIONBiochar oxidation could cause the mobilization of 30% of the adsorbed lead under acid conditions. Special attention should be given to biochar's intrinsic properties, such as O/C and H/C ratio, for the application of these materials in the treatment of contaminated soil. High‐temperature biochars would offer the additional advantage of managing the remediation of scenarios with low pH. © 2020 Society of Chemical Industry (SCI)

Reversible synthesis of GO: Role of differential bond structure transformation in fine-tuning photodetector response

The controlled modification of graphene’s electronic band structure poses serious challenges. In the present work, we study the effect of sp 2 cluster size variation on the electronic band gap and photoconductive properties of reduced graphene oxide (RGO). This is achieved by performing reversible functionalization of RGO with oxygen species. The reversible functionalization of RGO results in its partial transformation to graphene oxide (GO) so that the size of the sp 2 clusters within the sp 3 matrix varies, thereby affecting the π-π* band structure and photoconductive properties. The study reveals: (1) incremental creation/elimination of oxygenated surface bonds’ related energy states within the π-π* band; (2) customized tuning of the sp 2/sp 3 ratio; (3) the presence/absence of oxygenated states impacts the optical transition processes both from band-to-band and oxygenated states; and (4) the incremental addition/depletion of surface states in a tunable manner directly influences the carrier transport in the photoconductive device. Experiments show a two-stage transformation of RGO electronic properties with changing oxygen functionalities: oxidation (Stage I) and decomposition or erosion (Stage II). Sp 2 cluster size variation induced bandgap change was analyzed by Raman and photoluminescence studies, indicating the possibility for photodetection in a specific band encompassing NIR to UV, depending on the sp 2/sp 3 ratio. Energy-dispersive x-ray spectroscopy and Fourier transform infrared studies confirm the surface oxygenation/de-oxygenation during plasma treatment, and XRD confirms partial transformation of RGO to GO and its amorphization at higher plasma exposure times. In addition, the photodetector performance is optimized in terms of carrier generation-recombination and carrier-lattice scattering. Thus, manipulating better photoconductive response is possible through suitable handling of the parameters involved in the plasma treatment process. This is the first study on the influence of the sp 2/sp 3 ratio-induced lattice structure evolution on photodetection.

Elucidating hydrochar morphology and oxygen functionality change with hydrothermal treatment temperature ranging from subcritical to supercritical conditions

Hydrochar, used for numerous applications including solid fuel, adsorbent medium, anode material, and soil amendment, is the major solid product or unwanted byproduct resulting when biomass undergoes for subcritical or supercritical water treatment, respectively. Regardless of the reaction temperature, hydrochar forms from biomasses at different reaction kinetics. Our hypothesis in this study is morphology and oxygen functionality of hydrochar change with reaction temperature, especially from a subcritical to supercritical region. To test this hypothesis, hydrochar was produced from microcrystalline cellulose at 220 °C–420 °C with 40 °C interval with a reaction time of 30 min. The effects of subcritical and supercritical conditions of the hydrochar characteristics were investigated using a series of analytical tools including ultimate and proximate analyses, Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM), X-Ray Diffraction (XRD) analysis, Fourier-transform infrared spectroscopy (FTIR), and Boehm Titration. Results showed that oxygen-containing acidic functional groups reached the highest (1495 ± 25 μmol/g) at 260 °C and reduced afterward with an increase of temperature, although the elemental oxygen was reduced with the increase of reaction temperature. The particle size of hydrochar increases with the increase of temperature in the subcritical region but decreases in the supercritical region.

Blue M–Healing with Oxygen

Studies reveal that, world’s two-third of population suffers from chronic form of oral diseases and wounds.The principle etiological factor behind is a polymicrobial complex, which initiates the increase in theformation of reactive oxygen species e.g. per hydroxyl radicals, peroxyl radicals, aryl peroxyl radicalsetc. These ROS may cause damage to protein, lipid and DNA at sub molecular level. To combat thesemicrocosmic reactions, a revolutionary inventiveness for optimum oral health was carried out by a Europeanbased company in the form of a product, Blue-M. This acts as a continuous supplier of oxygen and byperfusion of this oxygen, it enhances healing of wound. It further aids in collagen synthesis, angiogenesisand is comprehensively Osseo inductive as well as anti-inflammatory in nature. Thus, this review aims atunderstanding the obligatory functions of oxygen and the biology behind neutralization of inflammation aswell as to recognize the essential benefits of this novel product, which in near future, after numerous studies,may even be used as an effective anti-microbial agent without developing resistance.

Surface modification of polyethylene microplastic particles during the aqueous-phase ozonation process

Microplastics coexist with the chemical reactive oxygen species in natural waters, however, there is still a lack to elucidate the effect of these radicals on the microplastic surficial oxidation. In this study, the ozonation of polyethylene microplastics was carried out under varying ozone dosages ranging from 4 to 7 mg/min for 60, 120 and 180 min, where its ozone uptake was iodometrically compared and surficial modification was spectroscopically analyzed using FTIR and XPS. For that, the lowest ozone uptake was 16% at 4 mg/min ozone supplied for 60 min whereas the highest was observed of 44% at 7 mg/min ozone added for 180 min. Moreover, in the FTIR analysis, carbonyl (1,600-1,800 cm&lt;sup&gt;-1&lt;/sup&gt;) and hydroxyl (3,200-3,600 cm&lt;sup&gt;-1&lt;/sup&gt;) indices were improved more than 20% and 13% when they were ozonized at 7 mg/min for 180 min compared to 4 mg/min for 60 min, respectively. XPS also revealed that 7 mg/min of ozone supplied for 180 min provided the highest of oxygen functionalities, but while there was no significant change in C-C bond. It can be concluded that the surficial modification of PE including formation of oxygen functionalities could be more preferably influenced by the reaction time than ozone dosages.

Oxygen-induced electrode activation and modulation essence towards enhanced anode redox chemistry for vanadium flow batteries

The vanadium flow battery (VFB) has seen a promising potential for use in large-scale energy storage. However, the sluggish anode redox chemistry still greatly limits the cycling performance of the VFBs. Herein, we realize an enhanced anode redox chemistry for the VFBs by tailoring the oxygen functional groups on carbon felts via a facile ozone-accelerated acid oxidation method, and more importantly uncover the modulation essence of p-band center in activated carbon felts. By introducing oxygen functional groups, the activated carbon felts exhibit both increased specific surface area and improved hydrophilicity over pristine carbon felts. Material and electrochemical characterizations indicate that an increased oxygen content in the carbon felts can substantially facilitate the V2+/V3+ redox kinetics. Benefiting from the enhanced V2+/V3+ kinetics, the VFB full cell delivers a superior energy efficiency of 72.8 % at 300 mA cm−2, and a long-term cycling stability is also achieved over 600 consecutive charge-discharge cycles at 150 mA cm−2 with only a 6.5% decay in energy efficiency. Most importantly, first principle calculations uncover that the oxygen function groups, especially carboxyl, can enhance the adsorption process but meanwhile to a certain extent suppress the charge transfer process for the V2+/V3+ redox reactions, which highlights the significance of delicate modulation of oxygen function groups on carbon felts to enhancing anode redox chemistry and full cell performance for the VFBs.