Spontaneous Chemical Reaction Research Articles

Confining Dendrite Growth Enabled By Ionically Conductive Interphase for Highly Stable Potassium Metal Anode

Potassium metal has been considered as one of the ultimate anode for rechargeable potassium batteries because of its high theoretical capacity (686 mAh g-1) and low electrode potential (~2.93 V vs. SHE). However, K metal is thermodynamically instable in aprotic electrolyte and uneven K plating usually leads to dendritic K metal deposition, resulting in low Coulombic efficiency and safety concerns.1,2In this study, we introduce potential strategy to stabilize the K metal anode via simple chemical interface control. The robust and ionically conductive passivation layer can be controllably designed by the spontaneous chemical reaction when a K metal foil kept in contact with a liquid phase potassium-polysulfide (0.05M K2S5 dissolved in DEGDME);3 this provides a strong guiding effect to form an electronically and ionically conductive solid electrolyte interphase (SEI) layer, enabling a dense K plating with dendrite-free morphology. The unique characteristics of the functionalized K-metal is fully evidenced by the Operando optical microscopy and phase field modeling in electrodeposition process. Under practical constraints (i.e. using lean electrolyte and thin polymer separator), the functionalized K-metal anode exhibits the ultra-long-term K plating-stripping cycles over 1200 h in a symmetrical cells and further highlights a practical applicability with high areal capacity and fast charging-discharging capability in full-cells using TiS2 cathode. References U.-H. Kim, G.-T. Park, B.-K. Son, G. W. Nam, J. Liu, L.-Y. Kuo, P. Kaghazchi, C. S. Yoon and Y.-K. Sun, Nat. Energy, 2020, 5, 860. J.-Y. Hwang, S.-T. Myung and Y.-K. Sun, Adv. Funct. Mater., 2018, 28, 1802938.J.-Y. Hwang, H. M. Kim, C. S. Yoon and Y.-K. Sun, ACS Energy Lett., 2018, 3, 540-541.

Stable lithium anode enabled by biphasic hybrid SEI layer toward high-performance lithium metal batteries

Lithium (Li) metal has been proposed as the most promising anode for secondary lithium batteries with high energy density due to its considerable theoretical capacity (3860 mAh g−1) and lowest electrochemical potential (-3.04 V vs standard hydrogen electrode). However, the uncontrollable dendrite Li issues over repeated plating/stripping process results in huge volume change, low Coulombic efficiencies (CEs), and poor cycling performance. Here, a solid electrolyte interphase (SEI) layer mainly consisting of biphasic hybrid Li3Sb and LiF has been successfully in situ constructed on Li surface by spontaneous chemical reaction between Li and SbF3. The modified SEI can induce Li ions depositing on the linked-particle layer resulting from the relative low lithium diffusion coefficient of SEI layer component. The Li/Li symmetric cells with SbF3-modified Li (SF-Li) anodes show stable cycling over 400 h at 3.0 mA cm−2 for 3.0 mAh cm−2. The Li-S batteries with SF-Li anodes and ether-based electrolyte can achieve steady long-term cycling performance and high CEs. Particularly, the high voltage LiCoO2 (LCO)/Li batteries with SF-Li anodes and carbonate-based electrolyte also deliver excellent electrochemical properties even at harsh conditions. This work offers a new strategy to regulate Li ion deposition and benefits for the further development of safe Li metal batteries (LMBs).

New optimization approach for amphoteric/magnetic ramie biosorbent in dyestuff adsorption

There is growing interest for the utilization of biomass for environmentally friendly adsorbents, and optimizing the complicated and multi-functional structure of biosorbents remains challenging. Herein, ramie waste biomass-based adsorbents with amphoteric/magnetic multi-structures via two different fabrication routes were constructed, studied and optimized to fill the gaps between multi-structure of biosorbent and performance requirements. The results show that the biosorbents exhibit excellent adsorption and magnetic recovery performance, while the biosorbent with amphiprotic-magnetic structure exhibits higher adsorption capacities for methylene blue and congo red with maximum 195.9 mg/g and 147.7 mg/g. These results are attributed to optimization of multi-structure by regulating the introduction strategy of amphiprotic groups and Fe3O4 magnetic nanoparticles. The adsorption processes of the biosorbents accord well with the pseudo-second-order kinetic model and Langmuir isotherm model, which suggests dyestuff are adsorbed via a monolayer spontaneous chemical reaction, and hydrogen bonding and electrostatic interaction are the dominant adsorption mechanisms. These demonstrate that the optimized preparation of the biosorbent improves the adsorption capacity, reusability, and stability, and provides a new perspective for the preparation of high-efficient biosorbents with multi-structures and the purification of dye-polluted wastewater.

Rational design of hierarchical Ni-Mo bimetallic Selenide/N-doped carbon microspheres toward high–performance potassium ion batteries

Potassium ion batteries (KIBs) have received a lot of attention in large-scale energy storage applications because of abundant potassium resources. However, owing to the poor structural durability of electrode materials and sluggish reaction kinetics, the commercialization of KIBs is challenging. Herein, we design a hierarchically structured Ni–Mo bimetallic selenide/N-doped carbon microsphere (NMSe/NC) as an advanced anode material for KIBs. The hierarchical Ni-Mo/polydopamine microsphere precursor, obtained from the spontaneous chemical reaction of NiMoO4 nanorods with dopamine hydrochloride, is converted into heterostructured-Ni–Mo selenide crystals confined in a hierarchical NC matrix via a two-step thermal treatment. The unique hierarchical surface structure and the synergistic effect of Mo and Ni species provide sufficient electrochemical reaction sites and promote the reaction kinetics. Furthermore, the proximate contact between the active materials and the N-doped carbon matrix can facilitate electron transportation and enhance the structural robustness of the electrode. Consequently, the resulting NMSe/NC hierarchical microspheres delivered a high reversible capacity of 332 mA h g−1 after 200 cycles (current density: 0.5 A g−1) and a remarkable rate capability of 206 mA h g−1 (current density: 2.0 A g−1). The excellent electrochemical performance of NMSe/NC indicates their potential for KIB commercialization in large-scale energy storage systems in the future.

Effect of holding time on the growth morphology of in-situ TiB2 particles

In this paper, in-situ TiB2/Al composites were prepared by the molten salt method. The effect of holding time on the growth morphology of TiB2 particles was investigated. The TiB2 particles were confirmed by XRD, SEM and TEM analysis. Based on thermodynamic calculations, the synthesis mechanism of TiB2 particles was analyzed. By observing the 3D morphology of TiB2 at different growth stages and combining it with the crystal structure of TiB2, the growth process was revealed. The results show that the TiB2 particles nucleate through a spontaneous chemical reaction. During the growth process, the morphology of TiB2 undergoes spherical, polyhedral, and finally grows into a flake hexagonal or a block hexagonal.

Pre-lithiated Edge-enriched MoS2 nanoplates embedded into carbon nanofibers as protective layers to stabilize Li metal anodes

Lithium metal batteries (LMBs) are favored due to their high energy densities. However, how to inhibit the growth of Li dendrites, slow down the volume expansion and realize the reversible utilization of Li anode are still big challenges for the practical feasibility. Herein, a pre-lithiated edge-enriched ultra-thin MoS2 embedded carbon nanofiber (PCNF/MoS2) framework was prepared as a protective layer to stablize Li metal anode, Mo and Li2S was in situ formed on the surface of Li foil by a facile spontaneous chemical reaction of MoS2 and Li. Among them, Mo significantly reduces the overvoltage of the Li nucleation, achieves homogeneous Li plating/stripping, guides Li deposition in the cavity of three-dimensional (3D) framework, and thus inhibits the Li dendrites growth. More importantly, Li2S, as an effective additive, facilitates uniform and robust solid electrolyte interface (SEI) formation with excellent chemical stability and high ionic conductivity, which successfully realizes stable Li anode. Thereafter, the PCNF/MoS2-Li composite anode exhibits excellent long cycle life over 750 h at 1 mA cm−2 with a capacity of 1 mAh cm−2 in the symmetrical cell. In addition, when the PCNF/MoS2-Li composite anodes were paired with LiFePO4 and LiNi0.8Co0.1Mn0.1O2 cathodes, the batteries delivered improved cycling stability and rate performance, providing a promising new avenue to achieve pratical LMBs.

Identification of Potential Drug Targets of Broad-Spectrum Inhibitors with a Michael Acceptor Moiety Using Shotgun Proteomics.

The Michael addition reaction is a spontaneous and quick chemical reaction that is widely applied in various fields. This reaction is performed by conjugating an addition of nucleophiles with α, β-unsaturated carbonyl compounds, resulting in the bond formation of C-N, C-S, C-O, and so on. In the development of molecular materials, the Michael addition is not only used to synthesize chemical compounds but is also involved in the mechanism of drug action. Several covalent drugs that bond via Michael addition are regarded as anticarcinogens and anti-inflammatory drugs. Although drug development is mainly focused on pharmaceutical drug discovery, target-based discovery can provide a different perspective for drug usage. However, considerable time and labor are required to define a molecular target through molecular biological experiments. In this review, we systematically examine the chemical structures of current FDA-approved antiviral drugs for potential Michael addition moieties with α, β-unsaturated carbonyl groups, which may exert an unidentified broad-spectrum inhibitory mechanism to target viral or host factors. We thus propose that profiling the targets of antiviral agents, such as Michael addition products, can be achieved by employing a high-throughput LC-MS approach to comprehensively analyze the interaction between drugs and targets, and the subsequent drug responses in the cellular environment to facilitate drug repurposing and/or identify potential adverse effects, with a particular emphasis on the pros and cons of this shotgun proteomic approach.

An electrodeposited MoS2-MoO3−x/Ni3S2 heterostructure electrocatalyst for efficient alkaline hydrogen evolution

To produce H2 more efficiently from water splitting, low-cost, highly active, and robust electrocatalysts based on the earth-abundant elements that could operate in alkaline solutions to lower the energy barrier of the hydrogen evolution reaction (HER) are desired. Herein, we firstly present the fabrication of an amorphous MoS2-MoO3−x/Ni3S2 heterostructure on the nickel foam (NF) substrate via a facile and low-cost electrochemical synthesis approach consisting of a spontaneous chemical reaction followed by one-step electrodeposition in a single solution. The chemical composition and the content of the bridging S22− sites (i.e., a highly active site for the HER) in the fabricated MoS2-MoO3−x/Ni3S2@NF could be conveniently modulated by controlling the temperature and applied potential during the electrodeposition. The optimized MoS2-MoO3−x/Ni3S2@NF shows an excellent electrocatalytic activity with a HER overpotential of 76 mV at 10 mA cm−2 and stabilizes for over 17 h under the HER conditions in a 1 M KOH electrolyte at room temperature, which are the best among the reported MoS2-based hybrid electrocatalysts for the alkaline HER. Experimental characterizations and theoretical calculations show that the excellent electrocatalytic performance of the fabricated MoS2-MoO3−x/Ni3S2 heterostructure could be attributed to the synergistic effect of the proper hydrogen binding free energies of MoS2 with abundant bridging S22− sites, the strong H2O adsorption of MoO3−x, and the strong adsorption of OH− to the Ni3S2. This study presents a delicately designed MoS2-based hybrid catalyst for efficient alkaline HER, which could shed light on the design and fabrication of inexpensive electrocatalysts for energy conversion.

Assessment of a novel aminated magnetic adsorbent with excellent adsorption capacity for dyes and drugs

Dyes and drugs with high toxicity and low biodegradability pose risk to human health and ecological security, and should be purified efficiently from effluents before discharge. Traditional adsorbents are limited by the insufficient active adsorption sites and low stability. In this study, a novel aminated magnetic adsorbent (MCTs) was fabricated via two cross-linking steps using chitosan and triethylenetetramine to fill the gaps between current adsorbent and performance requirements. The morphological and physicochemical characteristics of the as-prepared MCTs were determined and identified with the aid of several characterization techniques. The adsorption performance of dyes and drugs was also investigated and represented by their adsorption capacities. In particular, the adsorption capacities of Congo Red, Chicago Sky Blue, Reactive Brilliant Red, and Ibuprofen were 583.11, 465.01, 403.12, and 291.71 mg/g, respectively. They also remained at around 80% after four reuse cycles. MCTs were adsorbed via a monolayer spontaneous chemical reaction, and hydrogen bonding and electrostatic interaction were the dominant adsorption mechanisms. These results demonstrated that the preparation of MCTs via two cross-linking steps enhanced the adsorbents’ adsorption capacity, reusability, and stability. They provided a new perspective for the preparation of high-efficient adsorbents and the purification of dye- and drug-polluted wastewater.

Dual Pseudocapacitive Oxides Accelerate Kinetics of Sulfur Intermediates in Lithium-Sulfur Batteries

The sluggish electrochemical kinetics of sulfur species has impeded the wide adoption of lithium-sulfur battery, which is one of the most promising candidates for next-generation energy storage system. Here, we present the electronic and geometric structures of all possible sulfur species and construct an electronic energy diagram to unveil their reaction pathways in batteries, as well as the molecular origin of their sluggish kinetics. By decoupling the contradictory requirements of accelerating charging and discharging processes, we select two pseudocapacitive oxides to enable the efficient transport of electron/Li+ to and from sulfur intermediates respectively. After incorporating Li x Nb2O5/Nb2O5 as electron-ion source and MnO2/Li y MnO2 as electron-ion drain, the electrochemical kinetics of sulfur cathode is significantly accelerated by a factor of 5 times and 1.8 times, respectively. This strategy, which couples a fast-electrochemical reaction with a spontaneous chemical reaction to bypass a slow-electrochemical reaction pathway, offers a solution to accelerate an electrochemical reaction, providing new perspectives for the development of high-energy battery systems.

Reactivity Dynamics.

The chemical reactivity of a molecule as a whole or of an atom in a molecule varies during a chemical reaction. A variation of global and local reactivity descriptors in the course of a physicochemical process was studied within a quantum fluid density functional theory framework. Effects of a physical confinement and the electronic excitation therein were studied. In this Perspective, we also highlight the direction of a spontaneous chemical reaction in the light of the dynamical variants of the conceptual density functional theory-based electronic structure principles. An exhaustive state-of-the-art dynamical study is warranted in order to understand a chemical reaction from a reactivity perspective augmenting the associated molecular reaction dynamics analysis.

Dual redox mediators accelerate the electrochemical kinetics of lithium-sulfur batteries

The sluggish electrochemical kinetics of sulfur species has impeded the wide adoption of lithium-sulfur battery, which is one of the most promising candidates for next-generation energy storage system. Here, we present the electronic and geometric structures of all possible sulfur species and construct an electronic energy diagram to unveil their reaction pathways in batteries, as well as the molecular origin of their sluggish kinetics. By decoupling the contradictory requirements of accelerating charging and discharging processes, we select two pseudocapacitive oxides as electron-ion source and drain to enable the efficient transport of electron/Li+ to and from sulfur intermediates respectively. After incorporating dual oxides, the electrochemical kinetics of sulfur cathode is significantly accelerated. This strategy, which couples a fast-electrochemical reaction with a spontaneous chemical reaction to bypass a slow-electrochemical reaction pathway, offers a solution to accelerate an electrochemical reaction, providing new perspectives for the development of high-energy battery systems.

Thermodynamic Energy Efficiency of Electrochemical Systems Performing Simultaneous Water Desalination and Electricity Generation

An emerging class of electrochemical systems utilize redox-active chemicals as input to simultaneously desalinate water and produce electricity within a single cell. This contrasts with traditional desalination technologies, such as reverse osmosis, electrodialysis and capacitive deionization, which consume net electricity during desalination. The underlying reason is that traditional desalination technologies perform solely a separation process, while such chemical-energy driven systems perform a combined process consisting of a spontaneous chemical reaction and a separation. Thermodynamic energy efficiency (TEE) of traditional technologies is defined as the ratio of the minimum energy to drive the separation process reversibly to the energy needed to perform the separation in practice. However, such a definition is not appropriate for systems which co-generate electricity and desalinated water. We propose that for these latter systems, TEE should be defined as the device electricity output divided by the maximum available energy. We develop a theoretical framework predicting the maximum available energy yielded by a combined redox reaction-desalination process. We utilize our framework to explore various input redox chemistries, and predict a maximum energy output of up to ∼25.74 kWh per m3 of desalinated seawater. We further introduce and experimentally characterize a desalination fuel cell driven by a hydrogen-oxygen redox couple, and apply our model to provide a first-time quantification of its TEE.

Electrochemical removal of cadmium from a sulphate solution using a three-dimensional electrode

The aim of this study is to investigate the removal of cadmium from sulphate solutions via a batch cell by an electrochemical method. A cadmium/zinc couple was used to generate a spontaneous chemical reaction in the cell. Different parameters such as initial Cd(II) concentration, choice of electrode, and influence of pH were investigated in this work. After 2 h operation of the reactor with a three-dimensional electrode of reticulated vitreous carbon (RVC) cathode, more than 90% of cadmium was recovered from 10, 100 and 500 mg L−1 cadmium sulphate solutions. The electrogenerative system was successful in reducing 10 mg L−1Cd(II) to < 0.4 mg L−1 for 90 min, 100 mg L−1Cd(II) to <0.5 mg L−1 for 150 min, and for 500 mg L−1Cd(II) to <4 mg L−1 for 270 min. For porous graphite (PG) as the cathode material, to achieve 90% of removal, more time is needed especially for 500 mg L−1. Finally, the deposited cadmium was characterized using scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDX) and X-ray diffraction (XRD).

Toward the Sustainable Lithium Metal Batteries with a New Electrolyte Solvation Chemistry

AbstractHerein, a new solvation strategy enabled by Mg(NO3)2 is introduced, which can be dissolved directly as Mg2+ and NO3− ions in the electrolyte to change the Li+ ion solvation structure and greatly increase interfacial stability in Li‐metal batteries (LMBs). This is the first report of introducing Mg(NO3)2 additives in an ester‐based electrolyte composed of ternary salts and binary ester solvents to stabilize LMBs. In particular, it is found that NO3− efficiently forms a stable solid electrolyte interphase through an electrochemical reduction reaction, along with the other multiple anion components in the electrolyte. The interaction between Li+ and NO3− and coordination between Mg2+ and the solvent molecules greatly decreases the number of solvent molecules surrounding the Li+, which leads to facile Li+ desolvation during plating. In addition, Mg2+ ions are reduced to Mg via a spontaneous chemical reaction on the Li metal surface and subsequently form a lithiophilic Li–Mg alloy, suppressing lithium dendritic growth. The unique solvation chemistry of Mg(NO3)2 enables long cycling stability and high efficiency of the Li‐metal anode and ensures an unprecedented lifespan for a practical pouch‐type LMB with high‐voltage Ni‐rich NCMA73 cathode even under constrained conditions.

Study of Electrochemical Redox Reaction of CuSO4 Salt with Amoxicillin at Different Temperatures Using Glassy Carbon Electrode

The redox behavior of copper sulfate in absence and presence of Amoxicillin was studied at two different temperatures (288.15 and 298.15)K. The redox behavior was studied in 0.1 M HCl electrolyte, potential range from (1.5 to -1.5)V. The copper ions concentration is small ones ranging from (3.3×10-4 to 1.67×10-3)M. Only one reduction and one oxidation peaks are obtained in our results indicating the reduction and oxidation of the divalent copper ions to the zero valent copper metal. All the solvation cyclic voltammetry parameters were evaluated at the two temperatures used and their values were discussed for cupric ions in presence and absence of Amoxicillin. Also, the thermodynamic parameters for the interaction of copper ions with Amoxicillin as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. The thermodynamic parameters indicate that the reaction between cupric ions and Amoxicillin is chemical reaction (high negative Gibbs free energies values), good spontaneous (positive entropies) and endothermic chemical reaction (valuable positive values). Energy values of interaction between Amx and 2hg6 which obtained by molecular docking calculations indicate that Amx has an anticancer activity for liver cancer treatment

Chemically Prelithiated Hard-Carbon Anode for High Power and High Capacity Li-Ion Batteries.

Hard carbons (HC) have potential high capacities and power capability, prospectively serving as an alternative anode material for Li-ion batteries (LIB). However, their low initial coulombic efficiency (ICE) and the resulting poor cyclability hinder their practical applications. Herein, a facile and effective approach is developed to prelithiate hard carbons by a spontaneous chemical reaction with lithium naphthalenide (Li-Naph). Due to the mild reactivity and strong lithiation ability of Li-Naph, HC anode can be prelithiated rapidly in a few minutes and controllably to a desirable level by tuning the reaction time. The as-formed prelithiated hard carbon (pHC) has a thinner, denser, and more robust solid electrolyte interface layer consisting of uniformly distributed LiF, thus demonstrating a very high ICE, high power, and stable cyclability. When paired with the current commercial LiCoO2 and LiFePO4 cathodes, the assembled pHC/LiCoO2 and pHC/LiFePO4 full cells exhibit a high ICE of >95.0% and a nearly 100% utilization of electrode-active materials, confirming a practical application of pHC for a new generation of high capacity and high power LIBs.

Formation of stable polydopamine layer on polytetrafluoroethylene substrate by hybrid process involved plasma treatment and spontaneous chemical reactions

A hybrid process for the surface modification of polytetrafluoroethylene (PTFE) involving plasma pretreatment and spontaneous chemical reaction of polydopamine (PDA) was examined. This process could effectively prepare a stable PDA layer on the plasma-treated PTFE substrate. For analyzing the chemical reactions to form stable PDA layer, we confirmed the surface chemical reactions by spectroscopies and proposed a possible reaction process between dopamine and the plasma-treated PTFE surface. Moreover, it was found that a simple drying procedure could be promoted chemical bond formation between the plasma-treated PTFE and the PDA layer. The PDA layer was proved to be highly durable under harsh chemical conditions including both strongly acidic and basic conditions. The surface was proved to be robust and available for further functionalization by surface-initiated atom transfer radical polymerization (ATRP) of other monomers. The stability of the PDA layer was enough stable for immobilizing ATRP initiator and following polymerization process, that is, activator regenerated by electron transfer ATRP of methacrylate monomer could be initiated from the initiator at the surface. Overall, this procedure achieved practical and reliable surface functionalization of PTFE substrates, and would expand the potential applications of PTFE substrates in various industrial fields, including medicine.

Photodriven quantum teleportation of an electron spin state in a covalent donor-acceptor-radical system.

Quantum teleportation transfers the quantum state of a system over an arbitrary distance from one location to another through the agency of quantum entanglement. Because quantum teleportation is essential to many aspects of quantum information science, it is important to establish this phenomenon in molecular systems whose structures and properties can be tailored by synthesis. Here, we demonstrate electron spin state teleportation in an ensemble of covalent organic donor-acceptor-stable radical (D-A-R•) molecules. Following preparation of a specific electron spin state on R• in a magnetic field using a microwave pulse, photoexcitation of A results in the formation of an entangled electron spin pair D•+-A•-. The spontaneous ultrafast chemical reaction D•+-A•--R• → D•+-A-R- constitutes the Bell state measurement step necessary to carry out spin state teleportation. Quantum state tomography of the R• and D•+ spin states using pulse electron paramagnetic resonance spectroscopy shows that the spin state of R• is teleported to D•+ with high fidelity.

Thiuram Vulcanization Accelerators as Polysulfide Scavengers To Suppress Shuttle Effects for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered to be one of the most promising alternatives for next-generation high energy-density storage systems. Nevertheless, the notorious "shuttle effect" and sluggish kinetic conversion in actual operation seriously hamper its practical application. Herein, inspired by the action mechanism of vulcanization accelerators, dipentamethylenethiuram tetrasulfide (DPTT) is employed as a novel electrolyte additive. Just like a scavenger, DPTT sweeps lithium polysulfide by a spontaneous instant chemical reaction between them, and the latter is quickly converted to Li2S2, along with the generation of elemental S, which will be reduced to polysulfide again. This is beneficial for relieving the accumulation and shuttling of polysulfide in the electrolyte. Therefore, Li-S batteries with DPTT-containing electrolyte exhibit enhanced capacity retention and improved rate performance. With 4 wt % DPTT additive and 3.03 mg cm-2 S loading, the cell delivers a high initial capacity of 1227.6 mA h g-1 and excellent capacity retention of 914.7 mA h g-1 after 250 cycles at 0.5 C. This study provides a fresh insight into suppressing the shuttle effect and realizing high-performance Li-S batteries.