Spontaneous Chemical Reaction Research Articles

Topography and structural regulation-induced enhanced recovery of lithium from shale gas produced water via polyethylene glycol functionalized layered double hydroxide

Recovering lithium from wastewater generated during shale gas operations is essential for promoting sustainable resource utilization and safeguarding the environment. This study aimed to develop a lithium adsorbent by modifying lithium-aluminum layered double hydroxide (Li/Al-LDH) using varying concentrations of polyethylene glycol (PEG) of two distinct molecular weights. Remarkably, the application of a 10 % solution of PEG400 at 293 K and a liquid-to-solid ratio of 20 mL/g yielded a substantial enhancement in the lithium adsorption capacity, increasing from 2.50 mg/g to 3.61 mg/g. Characterization studies revealed positive alterations in the physicochemical attributes of Li/Al-LDH after the integration of PEG long chains, particularly in its surface and structural properties. Moreover, DFT calculations demonstrated an increase in Li+ binding energy from −1.05 eV to −3.24 eV. The lithium adsorption process in produced water using the modified material reached equilibrium within 15 min through a spontaneous chemical reaction. Its capability to release Li+ under neutral conditions offers an environmentally friendly advantage. With a stable cyclic adsorption capacity of around 4.00 mg/g over eight rounds, the material demonstrated remarkable recyclability. This research presents a pioneering advanced lithium adsorbent for the sustainable extraction of lithium from shale gas produced water, thereby advancing the new energy sector.

Removal of Hg(II) with MgAl-layered double hydroxide functionalized by schiff base ligands: Application and condition optimization

To effectively remove heavy metal Hg(II) from water bodies, a novel adsorbent of MgAl-layered double hydroxide (LDH) was designed and functionalized with Schiff base. The characterization results of the adsorbent (MgAl-LDH@SiO2-AG) show that the Schiff base polymer was successfully coated onto the outside surface of MgAl-LDH with hexagonal structure. The theoretical maximum adsorption capacity to Hg(II) is 228.46 mg/g at pH 7 and 298 K. The different pH solutions were investigated from pH 2 to 8, and the optimal capacity of MgAl-LDH@SiO2-AG toward Hg(II) achieves 268.7 mg/g at pH = 7.2, T = 36.8 °C, C0 = 32.1 mg/L and dosage = 0.083 g/L. In reality, the adsorbent not only exhibits efficient removal of Hg(II) in various water bodies, including lake water, river water, effluent from sewage treatment plant, but also has an excellent selectivity in electroplating wastewater containing different heavy metal ions. Low contents of TN and TP in real wastewater have less effect on the removal of Hg(II). Moreover, the prepared adsorbent had a good reusability and stability. The reaction mechanism mainly involves chelation with nitrogen/oxygen-containing groups and the predominant participation of nitrogen atoms in the Schiff base functional group. The removal of Hg(II) relies on the pseudo-second-order kinetics and Langmuir model, and is an endothermic and spontaneous chemical reaction. The present work offers a practical method for preparing highly effective adsorptive materials with the LDH composites and for the treatment of heavy metal Hg(II) from water bodies.

Preparation and Characterization of Ferrihydrite: Application in Arsenic Removal from Aqueous Solutions

Arsenic pollution is a public health hazard in Burkina Faso due to its impact on human health and water resources. To mitigate this pollution, ferrihydrite material has been synthesized and characterized to be used as adsorbent for arsenic removal in aqueous solutions. This study aimed to contribute to improve of access to clean drinking water by removing arsenic from water using ferrihydrite. Arsenic species such as As(III) and As(V) were removed through batch adsorption. Experiments were carried out in batch mode using arsenic aqueous solutions. The characterization of ferrihydrite using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), Infrared (IR), and Brunauer Emmett Teller (BET) showed that an amorphous and microporous 2-line ferrihydrite. The total specific surface area and pH at point of zero charge (pHpzc) were 184.518 m²/g and 9.41, respectively. The optimal adsorbent doses were 4 g/L for As (V) and 8 g/L for As (III). The optimum pH range for the adsorption of As (V) and As (III) was between 2 and 10, The maximum adsorption capacity was 15.07 mg/g for As(V) and 13.01 mg/g for As(III) with increasing concentration between 2 and 16 mg/L. Equilibrium time for As (V) and As (III) on ferrihydrite was found to be 720 min and 960 min, respectively. The adsorption of As(V) and As(III) was consistent with the Langmuir monolayer model on ferrihydrite. Arsenic adsorption was occurred according to spontaneous chemical reaction. Arsenic removal was occurred on a monolayer following the pseudo-second order kinetic.

On the Practicability of the Solid‐State Electrochemical Pre‐Sodiation Technique on Hard Carbon Anodes for Sodium‐Ion Batteries

AbstractHard carbon (HC) with low cost and high specific capacity is considered the appropriate anode material for sodium‐ion batteries (SIBs), but the low initial coulombic efficiency (ICE) caused by solid electrolyte interface (SEI) formation and inherent active defects impede its practical battery application. Here, the practicability of solid‐state electrochemical (SSE) pre‐sodiation technique for hard carbon anode is assessed to conquer such challenges. The uniformly pre‐sodiated HC (Pre‐HC) can be fabricated through the SSE reaction between the HC and preloaded sodium metal film without introducing a liquid electrolyte. After being immerged in the electrolyte, a thin artificial SEI with abundant inorganic species is formed on the surface of Pre‐HC due to the spontaneous chemical reaction, and the ICE of HC is improved from 76.0% to 107.9%. Full cell paired with Na3V2(PO4)3 cathode exhibits a high ICE of 94.0% with 70% of energy density augment (from 126.5 to 214.4 Wh kg−1) after anode pre‐sodiation. Pre‐HC anode still retains the pre‐sodiation capacity of 671.1 mAh gNa−1 after being stored in the dry air for 2 h. This work demonstrates the practical applicability of this SSE pre‐sodiation strategy to enhance the energy density of SIBs.

Catalytic Effect of Ammonium Thiosulfate as a Bifunctional Electrolyte Additive for Regulating Redox Kinetics in Lithium-Sulfur Batteries by Altering the Reaction Pathway.

Sluggish sulfur redox kinetics and incessant shuttling of lithium polysulfides (LiPSs) greatly influence the electrochemical properties of lithium-sulfur (Li-S) batteries and their practical applications. For this reason, ammonium thiosulfate (AMTS) with effective redox regulation capability has been proposed as a functional electrolyte additive to promote the bidirectional conversion of sulfur species and inhibit the shuttle effect of soluble LiPSs. During discharging, the S2O32- in AMTS can trigger the rapid reduction of LiPSs from long chains to short chains by a spontaneous chemical reaction with sulfur species, thereby decreasing the accumulation of LiPSs in the electrolyte. During charging, the NH4+ in the AMTS enhances the dissociation/dissolution of Li2S2/Li2S by hydrogen-binding interactions, which alleviates the electrode surface passivation and facilitates the reversible oxidation of short-chain sulfides back to long chains. The enhanced bidirectional redox kinetics brought about by AMTS endows Li-S cells with high reversible capacity, excellent cycle stability, and rate capability even under lean electrolyte conditions. This work not only illustrates an effective redox regulation strategy by an electrolyte additive but also investigates its catalytic reaction mechanism and Li corrosion behavior. The crucial criteria for screening additives that enable bidirectional redox mediation analogous to AMTS are summarized, and its application perspectives/challenges are further discussed.

Nitrogen Electrochemical Reduction into Ammonia: The Li-Mediated Pathway with Lights and Shadows

The lithium-mediated (Li-m) nitrogen reduction reaction (NRR) represents the most promising electrochemical process for renewable-driven and delocalized NH3 production. To move a step forward to the net-zero carbon emission policy and contrast the climate crisis, it is essential to find a complementary pathway to the Haber-Bosh (HB) process, independent from “grey” or “blue” H2 and combinable with renewables. Indeed, HB causes a global average of 2.86 tons of CO2 emitted per ton of NH3 [1].The outstanding reducing power of Li has been applied in different strategies; it is possible to distinguish between continuous processes and step-by-step systems. In the first case, N2 is reduced simultaneously to the protonation into NH3, while, in the second option, the Li nitridation is conducted in the absence of H+ to avoid the competitive hydrogen evolution reaction (HER).The continuous processes have nowadays reached a Faradaic efficiency approaching 100% [2], as well as a commercially relevant ammonia production rate of 153.28 μg/h*cm2 geo at a current density of 1 A/cm2 geo [3] in a batch cell at 20 bars of N2. These systems present some intrinsic drawbacks, such as the proton donor (e.g. ethanol) consumption and the system degradation, that still limit the scalability of the process. To overcome these limits, the E-NRR is recently studied in combination with H2 oxidation reaction and with proton carriers [4], [5].The step-by-step technology could ensure greater stability to the process exploiting the spontaneous chemical reaction between Li3N and H2O. Therefore, this pathway avoids organic molecule degradation, as well as H2 feedstock need and consumption [6]. Moreover, the Li–N2 reaction in a completely aprotic environment could maximize Li exploitation, enhancing scalability. Indeed, the Li reduction step is essential for the mediator recirculation, but it is the most energy-requiring step [6].Li nitridation has been studied both in a direct thermochemical reaction [6] and with promising Li–N2 galvanic cells [7]. In similarity with metallic Li–gaseous batteries (e.g. Li-O2 devices), Li-N2 devices have been recently tested both for NH3 production and for energy storage. Even if this technology is still in its infancy, a proof-of-concept of Li3N formation has been verified [7] and our laboratory is currently addressing this challenge within the SuN2rise project.

Deglycation activity of the Escherichia coli glycolytic enzyme phosphoglucose isomerase

Glycation is a spontaneous chemical reaction, which affects the structure and function of proteins under normal physiological conditions. Therefore, organisms have evolved diverse mechanisms to combat glycation. In this study, we show that the Escherichia coli glycolytic enzyme phosphoglucose isomerase (Pgi) exhibits deglycation activity. We found that E. coli Pgi catalyzes the breakdown of glucose 6-phosphate (G6P)-derived Amadori products (APs) in chicken lysozyme. The affinity of Pgi to the glycated lysozyme (Km, 1.1 mM) was ten times lower than the affinity to its native substrate, fructose 6-phosphate (Km, 0.1 mM). However, the high kinetic constants of the enzyme with the glycated lysozyme (kcat, 396 s−1 and kcat/Km, 3.6 × 105 M−1 s−1) indicated that the Pgi amadoriase activity may have physiological implications. Indeed, when using total E. coli protein (20 mg/mL) as a substrate in the deglycation reaction, we observed a release of G6P from the bacterial protein at a Pgi specific activity of 33 μmol/min/mg. Further, we detected 11.4 % lower APs concentration in protein extracts from Pgi-proficient vs. deficient cells (p = 0.0006) under conditions where the G6P concentration in Pgi-proficient cells was four times higher than in Pgi-deficient cells (p = 0.0001). Altogether, these data point to physiological relevance of the Pgi deglycation activity.

Self-Adaptive Liquid Film: Dynamic Realization of Dendrite-Free Zn Deposition Toward Ultralong-Life Aqueous Zn Battery.

The poor reversibility and stability of Zn metal anode (ZMA) caused by uncontrolled Zn deposition behaviors and serious side reactions severely impeded the practical application of aqueous Zn metal battery. Herein, a liquid-dynamic and self-adaptive protective layer (LSPL) was constructed on the ZMA surface for inhibiting dendrites and by-products formation. Interestingly, the outer LSPL consists of liquid perfluoropolyether (PFPE), which can dynamically adapt volume change during repeat cycling and inhibit side reactions. Moreover, it can also decrease the de-solvation energy barrier of Zn2+ by strong interaction between C-F bond and foreign Zn2+ , improving Zn2+ transport kinetics. For the LSPL inner region, in-situ formed ZnF2 through the spontaneous chemical reaction between metallic Zn and part PFPE can establish an unimpeded Zn2+ migration pathway for accelerating ion transfer, thereby restricting Zn dendrites formation. Consequently, the LSPL-modified ZMA enables reversible Zn deposition/dissolution up to 2000h at 1mA cm-2 and high coulombic efficiency of 99.8% at 4mA cm-2 . Meanwhile, LSPL@Zn||NH4 V4 O10 full cells deliver an ultralong cycling lifespan of 100 00 cycles with 0.0056% per cycle decay rate at 10 A g-1 . This self-adaptive layer provides a new strategy to improve the interface stability for next-generation aqueous Zn battery.

High Areal-Capacity Aqueous Manganese-Based Batteries Enabled by Redox Mediators

Aqueous manganese batteries based on deposition-dissolution of Mn2+/MnO2 reactions have aroused great attention due to their intrinsic low cost, high potential, and high energy.1, 2 However, the incomplete dissolution and exfoliated dead MnO2 would inevitably lead to capacity loss and poor cyclability at high areal capacity application.3, 4 Herein, we apply a redox mediator strategy to dissolve the accumulated MnO2 via a spontaneous chemical reaction between redox mediators iodide and MnO2.5,6 During the discharge process, the iodide (I–) could react with the residual MnO2 and be oxidized to I3 – that could be further reduced back to I– on the electrode, continuing this process until fully dissolved the accumulated MnO2. We will discuss detailed reaction mechanisms verified by ex-situ UV-vis spectroscopy, scanning electron microscopy, and X-ray diffraction. The zinc-manganese (Zn-Mn) battery with iodide mediator showed improved cycling stability at 2.5 mAh cm–2 (400 vs. 100 cycles, static mode) and 15 mAh cm–2 (225 vs. 60 cycles, flow mode). Areal capacity is one of the most important parameters determining system energy for deposition-based batteries.7 The Zn-Mn flow cell could demonstrate a high areal capacity application at 50 mAh cm–2 for 50 cycles. We will discuss how to expand this strategy to other manganese-based batteries and broaden the horizon of aqueous batteries.AcknowledgmentThis work is supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (project no. C1002-21G).Reference W. Chen, G. Li, A. Pei, Y. Li, L. Liao, H. Wang, J. Wan, Z. Liang, G. Chen, H. Zhang, J. Wang and Y. Cui, Nat. Energy, 2018, 3, 428-435. D. Chao, W. Zhou, C. Ye, Q. Zhang, Y. Chen, L. Gu, K. Davey and S.-Z. Qiao, Angew. Chem. Int. Ed. Engl., 2019, 58, 7823-7828. C. Liu, X. Chi, Q. Han and Y. Liu, Adv. Energy Mater., 2020, 10, 1903589. G. Liang, F. Mo, H. Li, Z. Tang, Z. Liu, D. Wang, Q. Yang, L. Ma and C. Zhi, Adv. Energy Mater., 2019, 9, 1901838. J. Lei, Y. Yao, Z. Wang and Y.-C. Lu, Energy Environ. Sci., 2021, 14, 4418-4426. J. Lei, Y. Yao, Y. Huang and Y.-C. Lu, ACS Energy Letters, 2022, DOI: 10.1021/acsenergylett.2c02524, 429-435. Y. Yao, J. Lei, Y. Shi, F. Ai and Y.-C. Lu, Nat. Energy, 2021, 6 (6), 582–588.

Significantly Improving the Initial Coulombic Efficiency of TiO2 Anode for Sodium-Ion Batteries.

Titanium dioxide (TiO2) can serve as a candidate anode material for sodium-ion batteries (SIBs) with the merits of their low cost, abundance, and environment friendliness. However, its low initial Coulombic efficiency (ICE) and sluggish sodium-ion diffusion greatly limit its further practical applications. Herein, we report a one-step prepotassiation strategy to modify commercial TiO2 by a spontaneous chemical reaction using potassium naphthalene (K-Nt). Prepotassiation effectively compensates for the irreversible Na loss and induces a homogeneous, dense, and robust artificial solid electrolyte interphase (SEI) on its surface. The well-distributed artificial SEI suppresses the excessive electrolyte decomposition, contributing to rapid interfacial kinetics and stable Na+ insertion/extraction. Therefore, such modified commercial TiO2 anodes demonstrate significantly improved ICE (72.4%) and outstanding rate performance (176.4 mAh g-1 at 5 A g-1). This simple and efficient method for promoting ICEs and interfacial chemistry also demonstrates universality and practical value for other anodes in SIBs.

Dual-particles functionalized hybrid biosorbent based on a facile etching-loading method for Pb2+ adsorption

Herein, novel cellulose-based biosorbent with dual-particles system was fabricated through a rapid and facile etching-loading method. The results shown the adsorbent exhibited efficient and stable adsorption performance which is owing to the firm embedding of functional particles without interference on the oxidized matrix. And the maximum adsorption capacity for Pb2+ reached 372.4 mg/g. The corresponding adsorption behavior was found to accord well with the pseudo-second-order kinetic model and Langmuir isotherm model, which reveals the rate-limiting phase of adsorption process is attributed to chemical adsorption type, and Pb2+ was adsorbed onto biosorbent surface by monolayer spontaneous chemical reaction. Surface physical attraction and chemical complexation bond are dominant adsorption mechanisms. And the recycling efficiency of biosorbent reached above 83% after 5 cycles. The above results indicate the hybrid functional structure by etching-loading route provided a novel method for rapid construction of promising and recyclable adsorbent for wastewater treatment.

In Situ Artificial Hybrid SEI Layer Enabled High‐Performance Prelithiated SiOx Anode for Lithium‐Ion Batteries

AbstractConsidered the promising anode material for next‐generation high‐energy lithium‐ion batteries, SiOx has been slow to commercialize due to its low initial Coulombic efficiency (ICE) and unstable solid electrolyte interface (SEI) layer, which leads to reduced full‐cell energy density, short cycling lives, and poor rate performance. Herein, a novel strategy is proposed to in situ construct an artificial hybrid SEI layer consisting of LiF and Li3Sb on a prelithiated SiOx anode via spontaneous chemical reaction with SbF3. In addition to the increasing ICE (94.5%), the preformed artificial SEI layer with long‐term cycle stability and enhanced Li+ transport capability enables a remarkable improvement in capacity retention and rate capability for modified SiOx. Furthermore, the full cell using Li(Ni0.8Co0.1Mn0.1)O2 and a pre‐treated anode exhibits high ICE (86.0%) and capacity retention (86.6%) after 100 cycles at 0.5 C. This study provides a fresh insight into how to obtain stable interface on a prelithiated SiOx anode for high energy and long lifespan lithium‐ion batteries.

Reversible Magnesium Metal Cycling in Additive-Free Simple Salt Electrolytes Enabled by Spontaneous Chemical Activation.

Rechargeable magnesium (Mg) batteries can offer higher volumetric energy densities and be safer than their conventional counterparts, lithium-ion batteries. However, their practical implementation is impeded due to the passivation of the Mg metal anode or the severe corrosion of the cell parts in conventional electrolyte systems. Here, we present a chemical activation strategy to facilitate the Mg deposition/stripping process in additive-free simple salt electrolytes. By exploiting the simple immersion-triggered spontaneous chemical reaction between reactive organic halides and Mg metal, the activated Mg anode exhibited an overpotential below 0.2 V and a Coulombic efficiency as high as 99.5% in a Mg(TFSI)2 electrolyte. Comprehensive analyses reveal simultaneous evolution of morphology and interphasial chemistry during the activation process, through which stable Mg cycling over 990 cycles was attained. Our activation strategy enabled the efficient cycling of Mg full-cell candidates using commercially available electrolytes, thereby offering possibilities of building practical Mg batteries.

Overcoming the Trade-Off between C2 H2 Sorption and Separation Performance by Regulating Metal-Alkyne Chemical Interaction in Metal-Organic Frameworks.

Designing porous materials for C2 H2 purification and safe storage is essential research for industrial utilization. We emphatically regulate the metal-alkyne interaction of PdII and PtII on C2 H2 sorption and C2 H2 /CO2 separation in two isostructural NbO metal-organic frameworks (MOFs), Pd/Cu-PDA and Pt/Cu-PDA. The experimental investigations and systematic theoretical calculations reveal that PdII in Pd/Cu-PDA undergoes spontaneous chemical reaction with C2 H2 , leading to irreversible structural collapse and loss of C2 H2 /CO2 sorption and separation. Contrarily, PtII in Pt/Cu-PDA shows strong di-σ bond interaction with C2 H2 to form specific π-complexation, contributing to high C2 H2 capture (28.7 cm3 g-1 at 0.01 bar and 153 cm3 g-1 at 1 bar). The reusable Pt/Cu-PDA efficiently separates C2 H2 from C2 H2 /CO2 mixtures with satisfying selectivity and C2 H2 capacity (37 min g-1 ). This research provides valuable insight into designing high-performance MOFs for gas sorption and separation.

Overcoming the Trade‐Off between C2H2 Sorption and Separation Performance by Regulating Metal‐Alkyne Chemical Interaction in Metal‐Organic Frameworks

AbstractDesigning porous materials for C2H2 purification and safe storage is essential research for industrial utilization. We emphatically regulate the metal‐alkyne interaction of PdII and PtII on C2H2 sorption and C2H2/CO2 separation in two isostructural NbO metal–organic frameworks (MOFs), Pd/Cu‐PDA and Pt/Cu‐PDA. The experimental investigations and systematic theoretical calculations reveal that PdII in Pd/Cu‐PDA undergoes spontaneous chemical reaction with C2H2, leading to irreversible structural collapse and loss of C2H2/CO2 sorption and separation. Contrarily, PtII in Pt/Cu‐PDA shows strong di‐σ bond interaction with C2H2 to form specific π‐complexation, contributing to high C2H2 capture (28.7 cm3 g−1 at 0.01 bar and 153 cm3 g−1 at 1 bar). The reusable Pt/Cu‐PDA efficiently separates C2H2 from C2H2/CO2 mixtures with satisfying selectivity and C2H2 capacity (37 min g−1). This research provides valuable insight into designing high‐performance MOFs for gas sorption and separation.

Origin of Surface Reconstruction in Lattice Oxygen Oxidation Mechanism Based‐Transition Metal Oxides: A Spontaneous Chemical Process

AbstractA fundamental understanding of surface reconstruction process is pivotal to developing highly efficient lattice oxygen oxidation mechanism (LOM) based electrocatalysts. Traditionally, the surface reconstruction in LOM based metal oxides is believed as an irreversible oxygen redox behavior, due to the much slower rate of OH− refilling than that of oxygen vacancy formation. Here, we found that the surface reconstruction in LOM based metal oxides is a spontaneous chemical reaction process, instead of an electrochemical reaction process. During the chemical process, the lattice oxygen atoms were attacked by adsorbed water molecules, leading to the formation of hydroxide ions (OH−). Subsequently, the metal‐site soluble atoms leached from the oxygen‐deficient surface. This work also suggests that the enhancement of surface hydrophilicity could accelerate the surface reconstruction process. Hence, such a finding could add a new layer for the understanding of surface reconstruction mechanism.

Origin of Surface Reconstruction in Lattice Oxygen Oxidation Mechanism Based-Transition Metal Oxides: A Spontaneous Chemical Process.

A fundamental understanding of surface reconstruction process is pivotal to developing highly efficient lattice oxygen oxidation mechanism (LOM) based electrocatalysts. Traditionally, the surface reconstruction in LOM based metal oxides is believed as an irreversible oxygen redox behavior, due to the much slower rate of OH- refilling than that of oxygen vacancy formation. Here, we found that the surface reconstruction in LOM based metal oxides is a spontaneous chemical reaction process, instead of an electrochemical reaction process. During the chemical process, the lattice oxygen atoms were attacked by adsorbed water molecules, leading to the formation of hydroxide ions (OH-). Subsequently, the metal-site soluble atoms leached from the oxygen-deficient surface. This work also suggests that the enhancement of surface hydrophilicity could accelerate the surface reconstruction process. Hence, such a finding could add a new layer for the understanding of surface reconstruction mechanism.

A Multifunctional Interphase Layer Enabling Superior Sodium-Metal Batteries under Ambient Temperature and -40°C.

The sodium (Na)-metal anode with high theoretical capacity and low cost is promising for construction ofhigh-energy-density metal batteries. However, the unsatisfactory interface between Na and the liquid electrolyte induces tardy ion transfer kinetics and dendritic Na growth, especially at ultralow temperature (-40°C). Herein, an artificial heterogeneous interphase consisting of disodium selenide (Na2 Se) and metal vanadium (V) is produced on the surface of Na (Na@Na2 Se/V) via an in situ spontaneous chemical reaction. Such interphase layer possesses high sodiophilicity, excellent ionic conductivity, and high Young's modulus, which can promote Na-ion adsorption and transport, realizing homogenous Na deposition without dendrites. The symmetric Na@Na2 Se/V cell exhibits outstanding cycling life span of over 1790h (0.5mA cm-2 /1 mAh cm-2 ) in carbonate-based electrolyte. More remarkably, ab initio molecular dynamics simulations reveal that the artificial Na2 Se/V hybrid interphase can accelerate the desolvation of solvated Na+ at -40°C. The Na@Na2 Se/V electrode thus exhibits exceptional electrochemical performance in symmetric cell (over 1500h at 0.5mA cm-2 /0.5 mAh cm-2 ) and full cell (over 700 cycles at 0.5 C) at -40°C. This work provides an avenue to design artificial heterogeneous interphase layers for superior high-energy-density metal batteries at ambient and ultralow temperatures.

Self-Discharging and Corrosion Problems in Vanadium Redox Flow Battery

Vanadium redox flow battery (VRFB) has a potential for large energy storage system due to its independence of energy capacity and power generation. VRFB is known to have challenges of high price, corrosion problem and lower energy efficiency. In this work, VRFB prototype with all components from existing parts sold in the market has been assembled and tested. Estimated electrochemical reactions are discussed for initial charging process with Vanadium Pentoxide powder as initial state to obtain fully charged battery state with V2+ ion in anolyte and VO2 + ion in catholyte. Material corrosion testes were done by immersing the material in a Vanadium electrolyte and by using the material as a bipolar plate in the VRFB system. Immersion test showed that copper, steel, lead and zinc were corroded badly. In bipolar plate material test, stainless steel 316, aluminum and silver plates were corroded after some hours of electric charging process. Simple carbon plastic composites and 3-mm thickness graphite plates were tested in the bipolar plate material test and failed due to corrosion problem as well. In the VRFB prototype, corrosion problems occurred on brass nipples, polyurethane plastic pipes and porous silicone seals. Stronger plastic components and better quality of silicone seals are needed for VRFB. Significant finding of this study is possible spontaneous chemical reaction within anolyte tank as a potential of self-discharging reaction which other researchers have not identified. Also, another finding from this study is that good bipolar plate for VRFB is not easily available in the market.

Spatially confined (Au core)/CeO2–(Au nanoclusters) hierarchical nanostructures as highly active and stable catalysts for CO oxidation

Developing highly active and stable catalysts is still extremely desirable, but represents a great challenge. Herein, we report a feasible one-pot approach to prepare in large scale Au core)/CeO2–(Au nanoclusters) (denoted as Au/CeO2–Au) nanostructures through a spontaneous chemical redox reaction without any surfactants, in which the Au nanoclusters were embedded into stacked CeO2. Such special architecture can offer abundant exposed Au atoms and oxygen vacancies, provide much more CeO2–Au interfaces, ensure the effective transfer of reactants and have clean exposed atoms. The Au/CeO2–Au nanostructures therefore exhibit a significantly improved activity of 100 % CO conversion at a much lower temperature of 115 °C compared with their counterparty. More importantly, the Au nanoclusters are spatially confined into CeO2, hindering the aggregation or further growth during catalysis. The conversion is therefore still kept at 100 % without any decay even the reaction was performed for as long as 300 h (12.5 days) and 20 cycles. We believed that this work is a new pathway to design effective catalysts with high activity and stability, especially for that involves small-sized metal nanoclusters.