Fast Charge Transfer Kinetics Research Articles

Boosting the Proton Intercalation via Crystal Plane Optimization of TiS2 for Cycling‐Stable Aqueous Zn‐Ion Batteries

AbstractTiS2 has received significant attention as a promising anode for “Rocking‐Chair”‐type aqueous Zn‐ion batteries due to the large interlayer spacing and low discharge plateau. However, the structural distortion caused by the embedding of divalent Zn2+ as well as the undesirable hydrogen evolution reaction (HER) severely affects their cycling stability. Herein, a facet‐dependent mechanism is first deeply investigated to understand charge storage behaviors of TiS2 via differential electrochemical mass spectrometry, in situ electrochemical quartz crystal microbalance, and in situ X‐ray diffraction characterizations. By regulating the exposed crystal facets of TiS2 from (001) (TS (001)) to (011) (TS(011)), HER can be effectively inhibited, and the charge storage mechanism is transformed from Zn2+ insertion/extraction dominating to H+ insertion/extraction dominating, resulting in faster charge transfer kinetics and strong structure stability during long‐term cycling. Hence, TS(011) delivers a higher reversible capacity of 212.9 mAh g−1 at 0.1 A g−1 and a strong cycling stability of 74% capacity retention over 1000 cycles, much better than that of TS (001) with a reversible capacity of 164.7 mAh g−1 at 0.1 A g−1, a capacity retention of 17% after 1000 cycles. These new findings can provide deep insight into the rational design of high‐performance intercalation‐type electrode materials for energy storage applications.

Activation of MnO6 Units via an Interfacial Electric Field: Electron Injection into Mn t2g for Rapid and Stable Sodium Ion Storage in CeO2 /MnOx.

Manganese-based oxides (MnOx ) suffer from sluggish charge diffusion kinetics and poor cycling stability in sodium ion storage. Herein, an interfacial electric field (IEF) in CeO2 /MnOx is constructed to obtain high electronic/ionic conductivity and structural stability of MnOx . The as-designed CeO2 /MnOx exhibits a remarkable capacity of 397 F g-1 and favorable cyclic stability with 92.13% capacity retention after 10,000 cycles. Soft X-ray absorption spectroscopy and partial density of states results reveal that the electrons are substantially injected into the Mn t2g orbitals driven by the formed IEF. Correspondingly, the MnO6 units in MnOx are effectively activated, endowing the CeO2 /MnOx with fast charge transfer kinetics and high sodium ion storage capacity. Moreover, In situRaman verifies a remarkably increased structural stability of CeO2 /MnOx , which is attributed to the enhanced Mn─O bond strength and efficiently stabilized MnO6 units. Mechanism studies show that the downshift of Mn 3d-band center dramatically increases the Mn 3d-O 2p orbitals overlap, thus inhibiting the Jahn-Teller (J-T) distortion of MnOx during sodium ion insertion/extraction. This work develops an advanced strategy to achieve both fast and sustainable sodium ion storage in metal oxides-based energy materials.

Crystal reconstruction of V2O3/carbon heterointerfaces via anodic hydration for ultrafast and reversible Mg‐ion battery cathodes

AbstractMagnesium‐ion batteries (MIBs) have promising applications because of their high theoretical capacity and the natural abundance of magnesium Mg. However, the kinetic performance and cyclic stability of cathode materials are limited by the strong interactions between Mg ions and the crystal lattice. Here, we demonstrate the unique Mg2+‐ion storage mechanism of a hierarchical accordion‐like vanadium oxide/carbon heterointerface (V2O3@C), where the V2O3 crystalline structure is reconstructed into a MgV3O7∙H2O phase through an anodic hydration reaction upon first cycle, for the improved kinetic and cyclic performances. As verified by in situ/ex situ spectroscopic and electrochemical analyses, the fast charge transfer kinetics of the V2O3@C cathode were due to the crystal‐reconstruction and chemically coupled heterointerface. The V2O3@C demonstrated an ultrahigh rate capacity of 130.4 mAh g−1 at 50 000 mA g−1 and 1000 cycles, achieving a Coulombic efficiency of 99.6%. The high capacity of 381.0 mA h g−1 can be attributed to the reversible Mg2+‐ion intercalation mechanism observed in the MgV3O7∙H2O phase using a 0.3 M Mg(TFSI)2/ACN(H2O) electrolyte. Additionally, within the voltage range of 2.25 V versus Mg/Mg2+, the V2O3@C exhibited a capacity of 245.1 mAh g−1 when evaluated with magnesium metal in a 0.3 M Mg(TFSI)2 + 0.25 M MgCl2/DME electrolyte. These research findings have important implications for understanding the relationship between the Mg‐ion storage mechanism and reconstructed crystal phase of vanadium oxides as well as the heterointerface reconstruction for the rational design of MIB cathode materials.image

An Ether‐Based Electrolyte Solvation Strategy for Long‐Term Stability and Ultra‐Low Temperature Li‐Metal Batteries

AbstractUnstable solid electrolyte interface (SEI) and dendrite growth hinder the development of rechargeable lithium‐metal batteries (LMBs) at low temperature (≤−20 °C). In this work, regulating the concentration of Li salt increases the proportion of anions in Li+ solvation structure, thereby forming a denser SEI on Li anode. The optimized solvation structure exhibits fast charge transfer kinetics and high‐voltage (dis)charge performance. As a result, Li||Cu cells with modified electrolyte work over 400 h and maintaining an average coulombic efficiency of 98.05%, the Li||LiNi0.8Co0.1Mn0.1O2 cells (N/P = 3) are capable of one hundred stable cycles with a capacity retention of 93.7% even at −40 °C. These findings confirm the effect of ion‐pairing and anion‐derived SEI on the long‐term cycling of LMBs, contributing a promising solution to the development of low‐temperature LMBs.

Benzene-fused porphyrin(2.1.2.1) array: synthesis, structure, and electrocatalytic hydrogen evolution.

The development of efficient molecular catalysts for the electrocatalytic hydrogen evolution reaction (HER) is very necessary and important for fuel cells. In this work, we report a new benzene-fused porphyrin(2.1.2.1) array, BPD, with a unique S-shaped molecular conformation. The electrochemistry of BPD displays multielectron donating and accepting properties owing to the two porphyrin(2.1.2.1) blocks and degenerate molecular orbitals. The electrocatalytic HER activity of BPD is remarkably higher-that is, BPD exhibited lower overpotential, faster HER kinetics, faster charge transfer kinetics, and extended catalytic stability-than that of the porphyrin(2.1.2.1) copper complex monomer.

Tuning ORR selectivity of π-conjugated cobalt corroles from 2e- to 4e-

Efficient oxygen reduction reaction (ORR) is crucial for the performance of fuel cells and other electrochemical devices. Seeking for stable and electrochemically selective 2e- and 4e- ORR electrocatalyst is yet a challenge, making the design extremely important and outmost of interest. In this study, we demonstrate a method to tune ORR selectivity by adjusting the local cobalt density through oligo-/polymerization of π-conjugated cobalt(III) A2B and A3-corroles to linear and two-dimensional matrix structures. These heterogeneous catalysts exhibit remarkable physicochemical properties, fast charge transfer kinetics, electrochemical reversibility, and high durability. Unselective three-electron transfer kinetics with n = 2.5–2.9 in between −0.20 V and +0.40 V vs. RHE are detected with the π-conjugated cobalt(III) A2B- corrole polymers. Highly selective four-electron kinetics with n = 3.7 in between −0.20 V and +0.40 V vs. RHE are detected by employing the cobalt A3-corrole oligomers during the ORR catalysis.

Fast charge transfer kinetics in Sv-ZnIn2S4/Sb2S3 S-scheme heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

Fast charge transfer kinetics in Sv-ZnIn2S4/Sb2S3 S-scheme heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

Formation of Iron Phosphide Nanobundles from an Iron Oxyhydroxide Precursor.

Iron phosphide (FeP) nanoparticles have excellent properties such as fast charge transfer kinetics, high electrical conductivity, and high stability, making them a promising catalyst for hydrogen evolution reaction (HER). A challenge to the wide use of iron phosphide nanomaterials for this application is the available synthesis protocols that limit control over the resulting crystalline phase of the product. In this study, we report a method for synthesizing FeP through a solution-based process. Here, we use iron oxyhydroxide (β-FeOOH) as a cost-effective, environmentally friendly, and air-stable source of iron, along with tri-n-octylphosphine (TOP) as the phosphorus source and solvent. FeP is formed in a nanobundle morphology in the solution phase reaction at a temperature of 320 °C. The materials were characterized by pXRD and transmission electron microscopy (TEM). The optimization parameters evaluated to produce the phosphorus-rich FeP phase included the reaction rate, time, amount of TOP, and reaction temperature. Mixtures of Fe2P and FeP phases were obtained at shorter reaction times and slow heating rates (4.5 °C /min), while longer reaction times and faster heating rates (18.8 °C/min) favored the formation of phosphorus-rich FeP. Overall, the reaction lever that consistently yielded FeP as the predominant crystalline phase was a fast heat rate.

Investigation of Electrochemical Stability of ALD Grown Li3PO4 Thin Films and Its Application in High‐Voltage PEO‐based All‐Solid‐State Lithium Batteries

AbstractIn lithium batteries, the interface between electrolytes and electrodes with optimized structural stability and fast charge transfer kinetics plays a pivotal role in achieving overall cycle and rate performance. Introducing a uniform interfacial layer that conducts Li+ ions while insulating electrons, through atomic layer deposition (ALD) of lithium compounds, has shown promise in facilitating lithium ion transport and enhancing interface stability. However, synthesizing lithium compounds with both robust chemical stability and a broad electrochemical window using ALD poses challenges due to the difficulty of obtaining desired products under specific ALD reaction conditions. In this study, this challenge by investigating Li3PO4 is addressed, a compound grown by ALD that exhibits a noteworthy property: the in situ formation of a more stable LiPO3 phase under high applied voltage. The LiPO3 phase possesses an extended theoretical stability window (LiPO3: 2.48‐5.00 V versus Li3PO4: 0.69‐4.21 V), and its emergence substantially enhances the electrochemical performance of all‐solid‐state lithium batteries based on polyethylene oxide (PEO). This work not only presents experimental evidence of the in situ transformation of the interfacial layer but also offers a pragmatic approach to realizing all‐solid‐state lithium batteries with elevated energy density, emphasizing safety and stability considerations.

Multiple Bubble Removal Strategies to Promote Oxygen Evolution Reaction: Mechanistic Understandings from Orientation, Rotation, and Sonication Perspectives.

Bubble coverage of catalytically active sites is one of the well-known bottlenecks to the kinetics of the oxygen evolution reaction (OER). Herein, various bubble removal approaches (electrode orientation, rotating, and sonication) were considered for the OER performance evaluation of a state-of-the-art Ir-based electrocatalyst. Key parameters, such as catalyst mass loss, activity, overpotential, and charge- and mass-transfer mechanisms, were analyzed. First, it was suggested that a suitable orientation of the working electrode facilitates coalescence and sliding bubble effects on the catalyst surface, leading to better electrochemical performance than those of the traditional rotating disk electrode (RDE) configuration. Then, the convection and secondary Bjerknes force were explained as the responsible phenomena in improving the OER activity in the RDE and sonication methods. Finally, simultaneous implementation of the methods enhanced the catalyst mass activity up to 164% and provided fast charge-transfer kinetics and low double-layer capacitance, which eventually led to a 22% reduction in overpotential, while the catalyst loss slightly increased from 1.93 to 3.88%.

Boosting adsorption and dissociation kinetics of magnesium-chloride ion pair via bismuth/indium-based artificial interface

The formation of passivating interphases on Mg-metal anode is impeding the wide employment of rechargeable Mg-metal batteries with less safety and cost concerns. Despite engineering artificial interlayers offers an efficient solution, it still falls short of expectation because of the compromised Mg plating/stripping performances in conventional electrolyte systems. In this work, a unique bismuth/indium-based artificial interface is introduced, which enables an exceptional reversibility (lowest nucleation overpotential of 189 mV than that (583 mV) of pristine Mg anode), high rate capability (a stable charge and discharge operation at 5.0 mA cm−2 without short circuit) and good temperaturetolerance (being cyclable over 10 °C and 50 °C) for the first time. This bismuth/indium-based artificial interface is constructed by facile displacement reactions between Bi(CF3SO3)3/In(CF3SO3)3 and Mg. The dominant interphases, including Bi, In and BiOx species, can be controllably tailored via adjusting the relative ratio and concentration of Bi(CF3SO3)3/In(CF3SO3)3. Theoretical calculation results accompanied by electrochemical experiments indicate that kinetically favorable adsorption and dissociation processes of Mg-Cl ion pair on this interface, affording good magnesiophilic property and fast charge transfer kinetics, are responsible for the improved Mg-metal anode properties.

Excellent ion storage properties of copper-cobalt composite selenide heterostructure in magnesium/lithium hybrid battery

Rechargeable magnesium batteries (RMBs) have emerged as a promising alternative to lithium-ion batteries (LIBs), given their high abundance and desirable safety characteristics. However, the strong polarization of divalent ions has hindered the satisfactory insertion and dissolution of Mg2+ ions in the cathode, thereby limiting the electrochemical performance of the system. To address this issue, magnesium/lithium hybrid batteries (MLHB) have been developed, using both Mg2+ and Li+ ions as carriers to enhance the electrochemical kinetic performance and maintain safety. In this study, a Cu2Se/CoSe heterostructured cathode is designed to extremely promote the electrochemical performance of MLHB. When it is applied to MLHB, the battery exhibites extremely high initial discharge capacity, reversible capacity and cycling stability. The initial discharge capacity obtains 385 mAh g−1 at 100 mA g−1, and a reversible capacity of 140 mAh g−1 is maintained after 200 cycles. The role of the special heterostructures and the effect of pre-lithiation on cathode materials are discussed in detail, on the basis of which a two-step storage mechanism of hybrid ions in Cu2Se/CoSe is proposed. This work lays the foundation for designing and constructing high-capacity, excellent cycle stability cathodes with fast charge-transfer kinetics.

Electrocatalytic and photocatalytic activities of hierarchically structured zinc oxide nanoparticles derived from cellulose paper-precipitated hydrozincite

This study presents a novel method for synthesizing hierarchical porous zinc oxide (ZnO) nanostructures by thermally decomposing green-synthesized hydrozincite. The hydrozincite was prepared at room temperature using zinc acetate dihydrate and calcium carbonate (CaCO3) in cellulose printing papers as the precipitating agent. The resulting ZnO particles exhibit a distinctive flower-like morphology, consisting of porous nanosheets composed of interconnected nanoparticles. The average crystallite size of the hierarchically structured zinc oxide nanoparticles, as determined via X-ray diffraction Rietveld refinement method, was found to be 18.8 nm when calcined at 500 °C. However, with increasing calcination temperature to 600, 700, and 800 °C, the average crystallite size also increased to 24.3, 30.4, and 47.2 nm, respectively. The ZnO synthesized at temperatures of 500 °C, 600 °C, and 700 °C exhibits higher electrocatalytic activity toward the hydrogen evolution reaction (HER) compared to both the ZnO synthesized at 800 °C and commercial ZnO. This enhanced performance can be primarily attributed to the nanosized ZnO particles, which provide a substantial surface area, high accessibility of active sites, and fast charge transfer kinetics. In terms of photocatalytic activity, all the samples show HER improvement under the UV light irradiation, attributed to the generation of photoexcited charge carriers. The ZnO synthesized at 800 °C and the commercial ZnO exhibit greater enhancements in photocatalytic activity compared to the other samples. This implies that larger solid particles with fewer nanopores result in a greater exposed surface area for UV-light absorption. The hierarchically structured ZnO nanoparticles demonstrate promising electrocatalytic and photocatalytic activities, as well as stability, opening up potential applications in various fields, including energy conversion and environmental remediation.

Carbon Nanosheets-Based Supercapacitor Materials: Recent Advances and Prospects.

The need for inexpensive and ecologically sustainable energy storage technologies is rising rapidly along with the severity of the world's environmental challenges as well as with the rising demand for portable electronics and hybrid vehicles. Supercapacitors have drawn a lot of attentions lately in this regard because of their ultrahigh power density, outstanding electrochemical stability, and environmental friendliness. Due to various advantages, carbon materials are the choice of designer for developing commercial electrodes for various applications including devising supercapacitors. Two-dimensional (2D) carbon nanosheets (CNSs) with a large surface area and excellent electronic transport properties have fired up the interest of researchers due to their unique properties and potential applications in energy storage. Such engineered 2D porous CNS may significantly improve the energy storage performance of supercapacitor by enabling fast ion transport and charge transfer kinetics. This article summarizes the most recent and significant advances in the area of activated, porous, graphene-based various CNSs and their composites with a special focus on their use as supercapacitor electrodes. A succinct overview about their syntheses and key characterizations regarding their different structural aspects have been discussed. The present challenges and prospects in using CNS in supercapacitor applications are highlighted.

Boron-Modulated Electronic-Configuration Tuning of Cobalt for Enhanced Nitric Oxide Fixation to Ammonia.

Electrocatalytic nitric oxide reduction (eNORR) to ammonia (NH3) provides an environmental route to alleviate NO pollution and yield great-value chemicals. The evolution of eNORR has been primarily hindered, however, by the poor reaction kinetics and low solubility of the NO in aqueous electrolytes. Herein, we have rationally designed a cobalt-based composite with a heterostructure as a highly efficient eNORR catalyst. In addition, by integrating boron to modulate the electronic structure, the catalyst CoB/Co@C delivered a significant NH3 yield of 315.4 μmol h-1 cm-2 for eNORR and an outstanding power density of 3.68 mW cm-2 in a Zn-NO battery. The excellent electrochemical performance of CoB/Co@C is attributed to the enrichment of NO by cobalt and boron dual-site adsorption and fast charge-transfer kinetics. It is demonstrated that the boron is pivotal in the enhancement of NO, the suppression of hydrogen evolution, and Co oxidation to boost eNORR performance.

A strategy of boosting the effect of carbon nanotubes in graphite-blended Si electrodes for high-energy lithium-ion batteries

High capacity silicon (Si) has been added in graphite electrodes to overcome the theoretical capacity limit of the carbonaceous anode. However, different active materials that store Li+ ions via intercalation and alloying mechanisms are prone to suffer electrical disconnection due to the large gap derived from their different volume shrinkage ratios during delithiation. Herein, to address this poor compatibility on graphite-blended Si composite electrode (Gr-SC), a strategic usage of carbon nanotubes (CNTs) as electric bridge between graphite and Si is investigated through the comparison of three different types of Si blended graphite anodes (Gr-SC, Gr-SC with CNTs as additive, and Gr-MSC having implanted multi-walled CNTs on Si). Among the comparison group, the selectively located MW-CNT around Si in Gr-MSC exhibits outperformed capacity retention (98.4 %) and faster charge transfer kinetics after 50 cycles in a half cell, demonstrating a great compatibility between graphite and Si. This study presents a comprehensive understanding on the role of CNTs as an electric bridge on the electrode exploiting multiple Li storage mechanisms which undergo dissimilar volume change.

Boosting the activity and CO tolerance for methanol oxidation reaction in alkaline media by constructing the Pt-TMNs electrocatalysts

Developing the efficient and high CO tolerance electrocatalysts is important for methanol oxidation reaction. In this study, a sequence ofcatalysts were constructed by introducting various transition metal nitrides (TMNs) to modify the Pt/C catalyst. The corresponding electrochemical performance were evaluated to investigate the activity, kinetics, charge transfer rate, CO tolerance and stability for MOR in alkaline media. Based on the structural characterization analysis from ICP-MS, XRD, HRTEM and XPS, it could be indicated that the participation of TMNs mainly brought the electronic effect, but not for the geometric effect. The evident difference did not exist in the nanoparticle size, morphology and crystallinity of the related catalysts. After the evaluation on the catalytic performance for alkaline MOR, The TMNs-modified catalysts exhibited higher activity and lower onset potential potential compared with the commercial Pt/C. Among them, Pt-NbN/C showed the highest mass activity with 9.56-fold that of the commercial Pt/C. The faster charge transfer kinetics and reaction rate were confirmed by Tafel and EIS results. CA measurements indicated that they also exhibited higher stability and anti-CO poisoning ability for alkaline MOR, consistent with the CO stripping experiments. To quantitatively describe the realtionship of the electronic effect on the catalytic activity and CO tolerance, the d-band center was employed as a parameter to bulid the corresponding function. Interestingly, it was proposed that the rational d-band center could lead high MOR performance and anti-CO poisoning ability. The introduction of TMNs brought the evident shift of the Pt d-band center and boosted the catalytic activity and anti-CO poisoning ability for alkaline MOR.

Improved Electrochemical Performance of Ni2P2O7 and Mn‐doped Ni2P2O7 Electrode Materials for Supercapacitor Applications

AbstractThe development of electrode materials for supercapacitors is really progressive and it still poses a huge challenge for researchers in many aspects. Doping of transition metals is indeed effective method because fast interfacial charge transfer kinetics has demonstrated their potential supercapacitive nature. The present work submits the structural, morphological and electrochemical performances of nickel pyrophosphate (Ni2P2O7) and manganese doped nickel pyrophosphate (Mn‐Ni2P2O7) thin film electrodes synthesized by chemical bath deposition method. The crystal structure of Ni2P2O7 obtained through X‐ray diffraction (XRD) is confirmed to be monoclinic which remains unaltered despite of Mn doping concentration. Morphological studies reveal that crystalline phase of Mn is intimately anchored on the surface of Ni2P2O7 which is beneficial for better charge transfer between transition metal and transition metal phosphates. A specific capacitance value of 603 F/g is obtained for 3 M concentration of Mn doped Ni2P2O7 from galvanostatic charge‐discharge curve at current density 1 A/g. This value is noticeably higher than what is obtained for the pure Ni2P2O7 indicating that Mn doping enhances the electrochemical performance of Ni2P2O7 thin films.

Bidirectional Construction of 3D Flexible Ti3C2Tx MXene Films for High-Performance Lithium-Ion Capacitors

Lithium-ion capacitors (LICs) are considered ideal devices, which bridge the energy and power density gap between lithium-ion batteries (LIBs) and supercapacitors (SCs). However, the mismatched kinetics between the cathode and anode remains an obstacle to the development of LICs. Herein, an anode with excellent flexibility and fast electrochemical reaction kinetics is designed for advanced LICs by coupling highly conductive single-walled carbon nanotubes (CNTs) with the bidirectionally designed Ti3C2Tx MXene (KTi3C2-O). In such a composite (KTi3C2-O/CNTs), the bidirectional design of Ti3C2Tx MXene based on the interlayers of K+ ions intercalation and interfaces of −O terminal groups modification will increase the interlayer distance, provide more active sites, and improve Li+ ions storage capacity; the introduction of CNTs forming a three-dimensional (3D) interpenetrating structure with KTi3C2-O can alleviate Ti3C2Tx MXene interlayer stacking and offer fast charge transfer kinetics. When evaluated as a self-supported anode of LIC, the LIC displays a high power density of 15.63 kW kg–1, a high energy density of 138.89 Wh kg–1, and an exceptional capacity retention of 77.75% over 10 000 cycles at 5 A g–1. Such a bidirectional construction strategy based on interlayer and interfacial modification provides new ideas for the design of such two-dimensional (2D) materials that can be applied in advanced energy storage devices.

Exploration of the lithium ions storage performance and mechanism of ZrN@reduced graphene oxide composite

The lithium ions storage behavior of zirconium nitride (ZrN) has been rarely explored. This work proposes a facile covalent self-assemble strategy to prepare the ZrN@reduced graphene oxide (ZrN@rGO) composite for enhanced lithium-ion battery (LIB). The X-ray photo spectra realizes that the strong Zr-C covalent bond is formed between ZrN and rGO. The Bader charge analysis features that the electron transferred from ZrN to rGO promotes the charge density at the ZrN@rGO heterointerface. Remarkably, the volume change decreases from 34% to 18% after the lithiation, corresponding to ZrN and ZrN@rGO, which highlights that the volume change of ZrN can be effectively alleviated by coupling with rGO. Further, the density functional calculation proves that the Li atom prefers to adsorb on Zr-N bridge site, and the adsorption energy of Li atom on ZrN@rGO (−2.01 eV) is higher than that on ZrN (−1.59 eV). Beyond that, the density of states of ZrN@rGO is significantly increased at the Fermi level, implying the high conductivity and fast charge transfer kinetics of ZrN@rGO. As a result, the specific capacity of ZrN@rGO remains at 199.5 mAh·g−1 at 1.0 A·g−1 after 1000 cycles.