Oxygen Oxidation Reactions Research Articles

Ex Situ Synthesis of Ti3C2@Fe-Ni-NC Heterostructure Towards an Efficient Bifunctional Electrocatalyst for High-Performance Zinc-Air Batteries

Zinc-air batteries (ZABs) with sustainable electrocatalysts have seen a lot of efforts to address oxygen reaction challenges to increase their lifespan and energy efficiency. Metal-organic frameworks (MOFs) and their derived materials are potential bifunctional electrocatalysts for addressing the oxygen reactions kinetics. However, under operational circumstances, MOFs and derived materials typically exhibit subpar electrochemical and conductivity. In this study, embedding MOF derived FeNi-N-C porous material in a few layer MXene nanosheets was effective strategy, enabling adequate conductivity, stability, and exposure number of active sites with better electrocatalytic activity towards oxygen reduction and oxidation reactions (ORR and OER). The resulting FeNi-NC@Ti3C2 hybrid exhibits notable bifunctional activities with a half-wave potential of 0.85 V and a low overpotential of 1.56 V, remarkable long-term cycle durability, as well as strong alcohol tolerance in an alkaline electrolyte. In addition, there is conductive MXene scaffold to achieve the highest ORR and OER activities with an ΔE value of 0.70 V. Furthermore, the FeNi-NC@Ti3C2 air-cathode-based assembled ZAB exhibits remarkable long-term cycling stability at 10 mA cm-2, a peak power density of 201 mW cm-2, and a high open circuit voltage (OCV) of 1.5 V. Ti3C2 MXene nanosheets provide a synergistic effect between two different materials in addition to protecting the surfaces of composite. This work provides a useful technique for enhancing ZAB's oxygen redox reactions, which could be used to aid in the development of efficient MOF@MXene based catalysts for electrochemical energy reactions.

Evaluation of low-temperature oxidation analysis and the development effect of high-pressure air injection in low-permeability reservoirs

In order to solve the problems of conventional water injection development difficulties and low recovery factor in low-permeability reservoirs, the method of high-pressure air drive is adopted to achieve the purpose of reservoir energy enhancement and efficiency improvement. This paper conducted an experimental study on the mechanism of low-temperature oxidation (LTO) for crude oil in the process of high-pressure air flooding, elaborated the relationship between the LTO properties of crude oil and the temperature, pressure, and water saturation of the reservoir, and analyzed the differences in LTO oxygen consumption and oil components under different reaction conditions. In addition, combined with the air flooding physical simulation experiment, the dynamic evolution law of recovery rate in the air flooding process was revealed. Findings from this inquiry indicate that an escalation in the oxidation temperature significantly amplifies the oxygen incorporation reaction within the crude oil matrix. This augmentation in oxidative conditions leads to an uptick in oxygen consumption, which subsequently precipitates a reduction in the lighter fractions of the oxidized oil while enriching its heavier components. Elevated pressures were found to enhance the propensity for the amalgamation of unstable hydrocarbons with oxygen, fostering comprehensive and heterogeneous oxidation reactions. Notably, an excessive presence of water was observed to detrimentally affect the thermal efficacy of crude oil oxidation processes. In the context of low-permeability reservoirs, air injection techniques have emerged as superior in effectuating oil displacement, although an increase in injection pressures has been associated with the phenomenon of gas channeling. Interestingly, adopting a sequential strategy of initiating water flooding before air flooding facilitated the conveyance of high-pressure air via established flushing channels, although it appeared to attenuate the intensity of crude oil oxidation, culminating in an oil recovery efficiency peaking at 51%.

New Design PdNi Heterogeneous Nanocatalysts for the Direct Synthesis of Hydrogen Peroxide

Hydrogen peroxide (H2O2) is a widely used chemical as an eco-friendly oxidizing agent, with water being the only byproduct of oxidation in applications like bleaching pulp and paper, making electronic semiconductors, chemical and detergent synthesis, and wastewater treatment. The direct synthesis approach is preferred to provide the environmentally friendly production of H2O2 for market requirements. Bimetallic PdNi nanocatalysts were chosen for this study because of their catalytic activity and the structural characteristics of the material system. First, for the development of order-structured bimetallic PdNi nanocatalysts based on mesoporous carbon template after hydrogen-assisted heat treatment at 750∘C. The transformation of the disordered structure into ordered intermetallically structured PdNi alloys with higher alloying extents was confirmed by X-ray absorption spectroscopy (XAS) and high-resolution transition electron microscopy (HR-TEM). Then, to improve the oxygen oxidation reaction, two-electron pathway selectivity was used by TiO2-C as a support-ordered structure material to facilitate strong metal-support interactions. XAS and X-ray photoelectron spectra (XPS) techniques show more clear evidence of metal-support interactions with electron transfer from defects in the TiO2-C support to the ordered alloyed PdNi nanocatalysts, resulting in record productivity and selectivity of H2O2 production at ambient conditions. The results demonstrated in this study will enlighten a reliable design of new heterogeneous nanocatalysts with ordered structure. Electron transfer between hybrid support and active sites can clarify the catalytic behavior and prompt further research during the direct synthesis of hydrogen peroxide.
 Keywords: hydrogen peroxide, direct synthesis, heterogeneous nanocatalysts PdNi, TiO2-C

Phthalocyanine-based bifunctional soluble hybrid catalyst for rechargeable lithium-oxygen batteries

A mixture of tetrabutylammonium lithium phthalocyanine (TBA-LiPc) and dilithium phthalocyanine (Li2Pc) (2:1 mol ratio) functions as a bifunctional soluble hybrid catalyst in tetraethylene glycol dimethyl ether (TEGDME) for a rechargeable lithium-oxygen cell. Cyclic voltammetry (CV) measurements of the hybrid catalyst in TEGDME show highly symmetrical peaks at 2.54 V and 3.22 V vs Li/Li+ corresponding to oxygen reduction and oxygen oxidation reactions, respectively. Long-term cycling of cells with PVP-modified graphene nanosheets (GNSs) coated hierarchical porous carbons (HPC) cathodes at a fixed capacity of 1200 mAh/g (carbon) exhibits 402 and 379 cycles in oxygen and dry-air, respectively.

Gold oxide formation on Au(111) under CO oxidation conditions at room temperature.

Although gold-based catalysts are promising candidates for selective low-temperature CO oxidation, the reaction mechanism is not fully understood. On a Au(111) model catalyst, we observe the formation of gold oxide islands under exposure to atmospheric pressures of oxygen or CO oxidation reaction conditions in an in situ scanning tunneling microscope. The gold oxide formation is interpreted in line with the water-enabled dissociation of O2 on the step edges of Au(111). Contaminants on the gold surface can strongly promote the gold oxide formation even on the terraces. On the other hand, TiO2 nanoparticles on the Au(111) do not show any influence on the formation of the gold oxide and are thus not providing a significant amount of atomic oxygen to the gold at room temperature. Overall, the presence of gold oxide is likely under industrial conditions.

A kinetic study on oxygen redox reaction of a double-perovskite reversible oxygen electrode—Part I: Experimental analysis

The carbon-free energy transition requires the spread of advanced technologies based on high-performing materials. In this framework and particularly referring to electrochemical energy converting systems, double perovskites are arousing more and more interest as mixed ionic electronic conductors with flexible manufacturing, appropriate tailoring for many tasks and high chemical stability. Among their possible applications, they form excellent oxygen electrodes in solid oxide cell technology used as fuel cells, steam/CO2 electrolysis cells and electrochemical air separation units. In view of the encouraging results shown by SmBa1−x Ca x Co2O5+δ co-doped double perovskite, this research work aims at a detailed analysis of SmBa0.8Ca0.2Co2O5+δ performance and the identification of kinetic paths for oxygen reduction and oxidation reactions. The electrochemical characterization was performed over a wide range of operation conditions to evaluate the electrode reversible behaviour and the interplay of the recognized phenomena governing the overall electrode kinetics.

Selective furfural conversion via parallel hydrogenation–oxidation on MOF-derived CuO/RuO2/C electrocatalysts via pulsed laser

Herein, Cu-metal–organic framework-derived CuO/C and CuO/RuO2/C were fabricated via pulsed laser ablation and calcination, demonstrating multifunctional electrocatalytic performances toward hydrogen and oxygen evolution, furfural hydrogenation, and oxidation reactions (HER, OER, FHR, and FOR) in alkaline solution. CuO/RuO2/C showed a high HER activity with 127-mV overpotential and 98.4-mV/dec Tafel slope. In contrast, during FHR, CuO/C converted 14.93-mM furfural to furfuryl alcohol (FFA) in 120-min with a Faradaic efficiency (FE) of 80.12 %, demonstrating a high yield. Similarly, CuO/RuO2/C showed a high OER activity with lowest overpotential ∼346-mV; subsequently, adding 50-mM furfural reduced that to 1.536 V vs. RHE. Furthermore, during FOR, furfural conversion was highly-favorable to achieve furoic acid (FA) upto 13.28-mM with a FE ∼77.56 % and C-balance of ∼77.56 %. Moreover, CuO/C‖CuO/RuO2/C electrolyzer was fabricated to simultaneously convert furfural into FA and FFA, saving-energy with enhanced-efficiency. Finally, in situ/operando electrochemical-Raman spectroscopy revealed the surface reorientation and MIII–O intermediate formation during HER and OER.

Practical Aspects in the Study of Biological Photosensitization Including Reaction Mechanisms and Product Analyses: A Do's and Don'ts Guide†.

The interaction of light with natural matter leads to a plethora of photosensitized reactions. These reactions cause the degradation of biomolecules, such as DNA, lipids, proteins, being therefore detrimental to the living organisms, or they can also be beneficial by allowing the treatment of several diseases by photomedicine. Based on the molecular mechanistic understanding of the photosensitization reactions, we propose to classify them in four processes: oxygen-dependent (type I and type II processes) and oxygen-independent [triplet-triplet energy transfer (TTET) and photoadduct formation]. In here, these processes are discussed by considering a wide variety of approaches including time-resolved and steady-state techniques, together with solvent, quencher, and scavenger effects. The main aim of this survey is to provide a description of general techniques and approaches that can be used to investigate photosensitization reactions of biomolecules together with basic recommendations on good practices. Illustration of the suitability of these approaches is provided by the measurement of key biomarkers of singlet oxygen and one-electron oxidation reactions in both isolated and cellular DNA. Our work is an educational review that is mostly addressed to students and beginners.

Development of a Novel Mild Depolymerization Method of Coal by Combining Oxygen Oxidation and Formic Acid Reduction Reactions.

Depolymerization of coal increases the tar yield in coal pyrolysis and enhances the thermoplasticity of the coal, which makes coal more favorable for producing coke and other value-added products like graphite electrodes, carbon fiber, aromatic chemicals, etc. In this study, the authors have proposed a novel coal depolymerization method that combines the oxidation reactions by molecular oxygen and the following reduction reactions by the coexisting gaseous formic acid to upgrade a bituminous coal at 90-150 °C under atmospheric pressure. The softening and melting performance of the treated coals was enhanced when oxygen and formic acid coexisted in gas phase at 90-130 °C. The amount of low-molecular-weight compounds in the coal treated at 90 °C in air containing formic acid vapor significantly increased by 29.0% of the amount of low-molecular-weight compounds in the raw coal measured by the solvent extraction method. Thus, the authors have succeeded in depolymerizing coal by the treatment under mild conditions, which is expected to contribute to coal's efficient utilization such as increasing the coal extracts and tar yield in the extraction and pyrolysis process, upgrading coal to be more suitable for the raw materials of coke, etc.

Oxidation and degradation of (epi)gallocatechin gallate (EGCG/GCG) and (epi)catechin gallate (ECG/CG) in alkali solution

The oxidative decomposition/degradation of two main tea flavanols, EGCG/GCG and ECG/CG, was studied in alkaline solution under ultrasonic-assisted thermal conditions. The study employed HPLC–ESI-ToF-MS to identify the products generated by atmospheric oxygen oxidation and various base-catalyzed reactions. Strong basic condition led to accelerated hydrolysis and oxidation of EGCG/GCG and ECG/CG and yielded gallic acid, de-galloyl flavanols and corresponding o-quinone derivatives. Meanwhile, peroxidation or base-catalyzed cleavage and rearrangement occurred extensively on C- and B-rings of flavanol and generated various simpler aldehydes or acids. Besides, a number of dimers/trimers were produced. This contribution provides empirical proof of oxidative degradation of flavanols under strong alkaline condition. Meanwhile, detailed reaction mechanisms of C-/B-ring degradation and dimerization/polymerization phenomena are proposed to help understand the structural changes of flavanols under strong alkaline conditions.

Study on mechanism of spray-mist-assisted laser processing of carbon fiber reinforced plastic

Carbon fiber reinforced plastic (CFRP) have wide application prospects due to its excellent mechanical properties. However, laser processing of CFRP will lead to a series of thermal damages, resulting in the mechanical properties being eroded. In this study, a method of spray mist to impact the wall to form a flowing and thin water film to assist laser low thermal damage processing for CFRP is carried out. Based on the oxidation reaction of oxygen to accelerate the etching efficiency of CFRP, a mixture of nitrogen and oxygen is used to assist the siphon nozzle to generate spray mist.The design of experiments (DOE) is used to study the influence of process parameters on machining, and the process parameters were optimized. The loss characteristics of spray mist on laser energy transmission were studied by the beam analyzer and the laser power meter. The dynamic ablation process of CFRP was photographed in situ by a high-speed camera, and the mechanism of spray mist-assisted laser processing of CFRP was studied by X-ray diffraction. The results show that the offset distance determines the machining quality, and the machining quality is significantly affected by laser power and cutting speed. When the oxygen content is 30%, a relative balance of cold and heat can be achieved, and a higher processing quality can be obtained. Spray mist causes laser scattering; the irradiated area and the energy loss increase; the smaller the offset distance, the larger the laser energy loss and the irradiated area. Most importantly, compared to the direct impact of the spray, the directional flow of the water film is beneficial to ensuring the quality and continuity of the laser processing.

Detonation process of high-speed flowing multiphase energetic mixture under high temperature and high pressure

The detonation process of high-speed flowing multiphase energetic cloud in a high-temperature and high-pressure semi-confined environment has extensive engineering backgrounds, and is a common form of energy output. A two-dimensional combustor model is established to numerically study the process and propagation laws of hexogen/air explosion, isopropyl nitrate/air explosion and hexogen/isopropyl nitrate/air explosion under 600 m/s flow. The results show that the high-speed flowing multiphase cloud will be subject to a first and second explosion under high temperature and high pressure. Under different concentrations of hexogen/air, the first explosion pressure of mixture is about 1.32 MPa; the second explosion pressure is 1.68–3.11 MPa and the peak temperature is 2732–4084 K, which first increase and then flatten with the increase of hexogen concentration. Under different concentrations of isopropyl nitrate/air, the first explosion pressure is about 1.28 MPa; the second explosion pressure is 1.59–6.49 MPa and two peak temperatures appear obviously during the explosion process, which increase with the increasing isopropyl nitrate concentration. For the three-phase mixture under hexogen: isopropyl nitrate=1:1, the detonation pressure and temperature increase with the increase of mixture concentration. Compared with hexogen/air, hexogen/isopropyl nitrate/air mixture has better detonation performance at high concentration (>1800 g/m3). The detonation performance of hexogen/isopropyl nitrate/air mixture at hexogen ratio ≤30% is similar to that of pure hexogen/air, and at proportion ≥40% is close to that of pure isopropyl nitrate/air. As the hexogen ratio increases, the explosion pressure and temperature of three-phase cloud present an inverted 'V' shape and reach the maximum when the hexogen ratio accounts for 90% of the multiphase mixture, which indicates that the detonation process of the three-phase hexogen/isopropyl nitrate/air mixture is the mutual coupling of decomposition exothermic reaction of hexogen and oxidation reaction of isopropyl nitrate and oxygen.

Electronic Metal-Support Interactions Between CuxO and ZnO for CuxO/ZnO Catalysts With Enhanced CO Oxidation Activity.

Metal-support interaction has been one of the main topics of research on supported catalysts all the time. However, many other factors including the particle size, shape and chemical composition can have significant influences on the catalytic performance when considering the role of metal-support interaction. Herein, we have designed a series of CuxO/ZnO catalysts as examples to quantitatively investigate how the metal-support interaction influences the catalytic performance. The electronic metal-support interactions between CuxO and ZnO were regulated successfully without altering the structure of CuxO/ZnO catalyst. Due to the lower work function of ZnO, electrons would transfer from ZnO to CuO, which is favorable for the formation of higher active Cu species. Combined experimental and theoretical calculations revealed that electron-rich interface result from interaction was favorable for the adsorption of oxygen and CO oxidation reaction. Such strategy represents a new direction to boost the catalytic activity of supported catalysts in various applications.

Tailoring Competitive Adsorption Sites by Oxygen-Vacancy on Cobalt Oxides to Enhance the Electrooxidation of Biomass.

The electrooxidation of 5-hydroxymethylfurfural (HMF) offers a promising green route to attain high-value chemicals from biomass. The HMF electrooxidation reaction (HMFOR) is a complicated process involving the combined adsorption and coupling of organic molecules and OH- on the electrode surface. An in-depth understanding of these adsorption sites and reaction processes on electrocatalysts is fundamentally important. Herein, the adsorption behavior of HMF and OH- , and the role of oxygen vacancy on Co3 O4 are initially unraveled. Correspondingly, instead of the competitive adsorption of OH- and HMF on the metal sites, it is observed that the OH- can fill into oxygen vacancy (Vo) prior to couple with organic molecules through lattice oxygen oxidation reaction process, which could accelerate the rate-determining step of the dehydrogenation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) intermediates. With the modulated adsorption sites, the as-designed Vo-Co3 O4 shows excellent activity for HMFOR with the earlier potential of 90 and 120mV at 10mA cm-2 in 1 m KOH and 1 m PBS solution. This work sheds insight on the catalytic mechanism of oxygen vacancy, which benefits designing a novel electrocatalysts to modulate the multi-molecules combined adsorption behaviors.

Thermal Behavior of Oil Shale Pyrolysis under Low-Temperature Co-Current Oxidizing Conditions.

The thermal behavior of the Huadian oil shale during low-temperature co-current oxidizing pyrolysis was studied by lab-scale experiments under different basic pyrolysis temperatures and input gas flow rates. The results showed that, in the process of oil shale co-current oxidizing pyrolysis, the increasing input gas flow rates under the same basic pyrolysis temperatures can significantly enhance the heat generation of oil shale. Meanwhile, it can be seen from the temperature variation characteristics of oil shale that the heat released by the oxidation reaction of semicoke and oxygen is enough to support the thermal decomposition of organic matter without supplemental heating. Moreover, it can be concluded from the 92.06% effective recovery of shale oil that a high yield of oil without a significant loss can be achieved. Finally, compared with increasing basic pyrolysis temperatures, the increased input gas flow rates have a more obvious effect on improving the effective recovery of shale oil.

Effect of Ni Content on Anionic Redox Activity in Ru-Containing Li-Rich Cathode Material

The high energy density of Li-rich layered oxides is associated with anionic redox reaction as it can deliver extra capacity. Herein, using first-principles calculations, we do a contrastive study of anionic redox mechanism in two Li-rich layered oxides, i.e., Li1.167Ni0.167Ru0.667O2 (Li7NiRu4O12) and Li1.167Ni0.333Ru0.5O2 (Li7Ni2Ru3O12), which are marked as LNR4O and LN2R3O, respectively. Our results reveal that the anionic oxidation potential is observed at around 3.95 V in LN2R3O, while, at around 4.31 V, oxygen oxidation reaction can only be achieved in LNR4O. The difference of anionic redox activity can be attributed to the different local oxygen environments between these two materials. Due to the relatively higher content of Ni in the LN2R3O, there are two additional local environments around oxygen (O-Li4NiRu and O-Li3Ni2Ru). Lattice oxygen is more easily oxidized in these two oxygen configurations, which explains the lower anionic oxidation potential in the LN2R3O. In addition, despite not containing linear Li-O-Li configuration, oxygen in the O-Li3Ni2Ru can still have anionic redox activity upon delithiation, which indicates that the anionic redox may not be only determined by linear Li-O-Li configuration. Our finding broadens the fundamental understanding of anionic redox mechanism in Li-rich oxides.

Cycling mechanism of Li2MnO3: Li–CO2 batteries and commonality on oxygen redox in cathode materials

Summary Li2MnO3 has been considered to be a representative Li-rich compound with active debates on oxygen activities. Here, by evaluating the Mn and O states in the bulk and on the surface of Li2MnO3, we clarify that Mn(III/IV) redox dominates the reversible bulk redox in Li2MnO3, while the initial charge plateau is from surface reactions with oxygen release and carbonate decomposition. No lattice oxygen redox is involved at any electrochemical stage. The carbonate formation and decomposition indicate the catalytic property of the Li2MnO3 surface, which inspires Li-CO2/air batteries with Li2MnO3 acting as a superior electrocatalyst. The absence of lattice oxygen redox in Li2MnO3 questions the origin of the oxygen redox in Li-rich compounds, which is found to be of the same nature as that in conventional materials based on spectroscopic comparisons. These findings provide guidelines on understanding and controlling oxygen activities toward high-energy cathodes and suggest opportunities on using alkali-rich materials for catalytic reactions.

Towards Moisture Tolerant Aprotic Lithium-Air Batteries Via Reversibly Cycling LiOH

In the light of recent commitments from several European countries to ban the sale of internal combustion engine vehicles in the coming decades, the race to develop electrical storage strategies beyond the capabilities of lithium ion batteries is intensifying considerably. Amongst the many different options, Li-air batteries (LABs) have attracted significant attention due to their comparable energy density to fossil fuels1. Despite of its potential, several fundamental challenges remain to be overcome for their successful development2-4. Amongst these challenges, the instability of the typical discharge products (LiO2 and Li2O2) in the presence of moisture and CO2 represents a fundamental stumbling block5.The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypassing the inherent limitations caused by the instability of their typical discharge products6. The use of the I-/I3 - redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging to develop due to the multiple reaction paths induced by the oxidation of I- on cell charging7. In this work we demonstrate a reversible LiOH-based Li-O2 battery cycling through a 4 e-/O2 process with low charging overpotential (below 3.5 V vs Li/Li+)8. This is achieved by increasing the oxidizing power of I3 -, which shifts the charging mechanism from IO-/IO3 - formation to O2 evolution. C. P. Grey and J. M. Tarascon, Nature Materials, 2017, 16, 45 G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson and W. Wilcke, The Journal of Physical Chemistry Letters, 2010, 1, 2193 D. Aurbach, B. D. McCloskey, L. F. Nazar and P. G. Bruce, Nature Energy, 2016, 1, 16128. D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, MRS Bulletin, 2014, 39, 443. N. Mahne, B. Schafzahl, C. Leypold, M. Leypold, S. Grumm, A. Leitgeb, Gernot A. Strohmeier, M. Wilkening, O. Fontaine, D. Kramer, C. Slugovc, Sergey M. Borisov and Stefan A. Freunberger, Nature Energy, 2017, 2, 17036. T. Liu, M. Leskes, W. Yu, A. J. Moore, L. Zhou, P. M. Bayley, G. Kim and C. P. Grey, Science, 2015, 350, 530. C. M. Burke, R. Black, I. R. Kochetkov, V. Giordani, D. Addison, L. F. Nazar and B. D. McCloskey, ACS Energy Letters, 2016, 1, 747. I. Temprano, T. Liu, E. A. Petrucco, J. H. J. Ellison, G. Kim, E. Jónsson and C. P. Grey, ChemRxiv, 2020, 12221717.v1. Figure 1

Toward Reversible and Moisture-Tolerant Aprotic Lithium-Air Batteries

Summary The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypass the inherent limitations caused by the instability of their typical discharge products, LiO2 and Li2O2. The use of the I−/I3− redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging due to the multiple reaction paths induced by the oxidation of I− on cell charging. In this work, we introduce an ionic liquid to a glyme-based electrolyte containing LiI and water and demonstrate a reversible LiOH-based Li-O2 battery cycling that operates via a 4 e−/O2 process with a low charging overpotential (below 3.5 V versus Li/Li+). The addition of the ionic liquid increases the oxidizing power of I3−, shifting the charging mechanism from IO−/IO3− formation to O2 evolution.

Towards Moisture Tolerant Aprotic Lithium-air Batteries via Reversibly Cycling LiOH

In the light of recent commitments from several European countries to ban the sale of internal combustion engine vehicles in the coming decades, the race to develop electrical storage strategies beyond the capabilities of lithium ion batteries is intensifying considerably. Amongst the many different options, Li-air batteries (LABs) have attracted significant attention due to their comparable energy density to fossil fuels1. Despite of its potential, several fundamental challenges remain to be overcome for their successful development2-4. Amongst these challenges, the instability of the typical discharge products (LiO2 and Li2O2) in the presence of moisture and CO2 represents a fundamental stumbling block5.The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypassing the inherent limitations caused by the instability of their typical discharge products6. The use of the I-/I3 - redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging to develop due to the multiple reaction paths induced by the oxidation of I- on cell charging7. In this work we demonstrate a reversible LiOH-based Li-O2 battery cycling through a 4 e-/O2 process with low charging overpotential (below 3.5 V vs Li/Li+). This is achieved by increasing the oxidizing power of I3 -, which shifts the charging mechanism from IO-/IO3 - formation to O2 evolution. 1. C. P. Grey and J. M. Tarascon, Nature Materials, 2017, 16, 45–56.2. G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson and W. Wilcke, The Journal of Physical Chemistry Letters, 2010, 1, 2193-2203.3. D. Aurbach, B. D. McCloskey, L. F. Nazar and P. G. Bruce, Nature Energy, 2016, 1, 16128.4. D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, MRS Bulletin, 2014, 39, 443-452.5. N. Mahne, B. Schafzahl, C. Leypold, M. Leypold, S. Grumm, A. Leitgeb, Gernot A. Strohmeier, M. Wilkening, O. Fontaine, D. Kramer, C. Slugovc, Sergey M. Borisov and Stefan A. Freunberger, Nature Energy, 2017, 2, 17036.6. T. Liu, M. Leskes, W. Yu, A. J. Moore, L. Zhou, P. M. Bayley, G. Kim and C. P. Grey, Science, 2015, 350, 530-533.7. C. M. Burke, R. Black, I. R. Kochetkov, V. Giordani, D. Addison, L. F. Nazar and B. D. McCloskey, ACS Energy Letters, 2016, 1, 747-756. Figure 1