Nanostructured Electrode Materials Research Articles

Exsolution of Embedded Nanoparticles in Defect Engineered Perovskite Layers.

Exsolution phenomena are highly debated as efficient synthesis routes for nanostructured composite electrode materials for the application in solid oxide cells (SOCs) and the development of next-generation electrochemical devices for energy conversion. Utilizing the instabilityof perovskite oxides, doped with electrocatalytically activeelements, highly dispersed nanoparticles can be preparedattheperovskite surface under the influence of a reducingheattreatment. For the systematic study of the mechanistic processes governing metal exsolution, epitaxial SrTi0.9Nb0.05Ni0.05O3-δ thin films of well-defined stoichiometry are synthesized and employed as model systems to investigate the interplay of defect structures and exsolution behavior. Spontaneous phase separation and the formation of dopant-rich features in the as-synthesized thin film material is revealed by high-resolution transmission electron microscopy (HR-TEM) investigations. The resulting nanostructures are enriched by nickel and serve as preformed nuclei for the subsequent exsolution process under reducing conditions, which reflects a so far unconsidered process drastically affecting the understanding of nanoparticle exsolution phenomena. Using an approach of combined morphological, chemical, and structural analysis of the exsolution response, a limitation of the exsolution dynamics for nonstoichiometric thin films is found to be correlated to a distortion of the perovskite host lattice. Consequently, the incorporation of defect structures results in a reduced particle density at the perovskite surface, presumably by trapping of nanoparticles in the oxide bulk.

An enhanced electrochemical energy storage performance based on porous activated carbon and hard carbon derived from natural maple leaf

The recent development of the nanostructured electrode materials with a large porous carbon structure assures the next-generation material for the high-energy storage application. Herein, we report hard carbon (HC), and activated carbon (AC) materials from natural maple leaf derived. A facilely synthesized zinc chlorate presence and non-presence maple leaf were prepared for the pyrolysis temperature of 800 °C under the nitrogen atmosphere. Various analytical techniques investigated the as-prepared HC and AC samples. The HC and AC modified electrode performances were analyzed using cyclic voltammetry (CV) and galvanostatic charge/discharge in the presence of 6.0 M KOH electrolyte. The most efficient AC and HC performance derived from maple leaves shows the specific capacitance values of 217 F g−1 and 118 F g−1, respectively. The AC-modified electrode showed a promising candidate for high energy storage performance for a practical application.

Solvothermal/Hydrothermal Manufacturing of Carbon Nanotubes for Hydrogen storage: A Comparative Study

Investigation on the manufacturing of multi-walled carbon nanotubes (MWNTs) by solvothermal and hydrothermal procedure and the electrochemical behavior of these nanostructured electrode materials for hydrogen storage has been presented. The physical and morphological properties of prepared carbon nanotubes were studied by X-ray diffraction (XRD), Scanning, and Transmission electron microscopy (SEM and TEM). Furthermore, the electrochemical properties of MWCNTs were revealed by galvanostatic charge-discharge and measurement of cyclic voltammetry and the results revealed that both MWNTs exhibited higher electrochemical capacitance and stable cycling performance. Interestingly, MWNTs synthesized from hydrothermal procedure shows an extreme discharge capacity of 423 mAh/g, concerning hydrogen storage of ∼ 1.5 wt%, and MWNTs synthesized from solvothermal procedure shows a capacity of discharge 394.8 mAh/g. corresponds to ∼ 1.4 wt%, was attained reproducibly at 25 °C for about 100 mg of MWCNTs. This outcome infers that the MWNTs are extremely assuring electrochemical hydrogen storage materials for PEM fuel cells and rechargeable batteries.

Flexible Transparent Supercapacitors: Materials and Devices

AbstractThe progressive development of flexible transparent portable electronic devices is in urgent need of matching power sources. Flexible transparent supercapacitors (FTSCs) are the core resources due to their high optical transmittance, endurable mechanical flexibility, excellent electrochemical performance, and facilely accessible device configuration. This review organizes the rational design of nanostructured electrode materials toward FTSCs. First, the structure, mechanism, and property of FTSCs are introduced. Then, the design principles of diverse electrode materials are discussed to achieve flexible transparent conductive electrodes (FTCEs) with different figure of merits (both electrical FoMe and capacitive FoMc), mechanical strength, and environmental stability. Following the achievements in multifunctional FTSCs focusing on film‐supercapacitors, micro‐supercapacitors, electrochromic supercapacitors, photo‐supercapacitors, and battery‐like supercapacitors are also highlighted. Finally, the current challenges and future perspectives on viable materials in the construction of FTSCs to power portable electronics are outlined.

Direct Electrochemical Enzyme Electron Transfer on Electrodes Modified by Self-Assembled Molecular Monolayers

Self-assembled molecular monolayers (SAMs) have long been recognized as crucial “bridges” between redox enzymes and solid electrode surfaces, on which the enzymes undergo direct electron transfer (DET)—for example, in enzymatic biofuel cells (EBFCs) and biosensors. SAMs possess a wide range of terminal groups that enable productive enzyme adsorption and fine-tuning in favorable orientations on the electrode. The tunneling distance and SAM chain length, and the contacting terminal SAM groups, are the most significant controlling factors in DET-type bioelectrocatalysis. In particular, SAM-modified nanostructured electrode materials have recently been extensively explored to improve the catalytic activity and stability of redox proteins immobilized on electrochemical surfaces. In this report, we present an overview of recent investigations of electrochemical enzyme DET processes on SAMs with a focus on single-crystal and nanoporous gold electrodes. Specifically, we consider the preparation and characterization methods of SAMs, as well as SAM applications in promoting interfacial electrochemical electron transfer of redox proteins and enzymes. The strategic selection of SAMs to accord with the properties of the core redox protein/enzymes is also highlighted.

Fabrication of graphene supported binary nanohybrid with multiple approaches for electrochemical energy storage applications

In the current study, we have fabricated Mn-doped Co3O4 nanoparticles (Mn.Co3O4 NPs) and their binary nanohybrid with r-GO nanosheets (Mn.Co3O4/r-GO) and decorated it directly on the nickel foam (NF) via a single-step hydrothermal method. The Mn.Co3O4/r-GO nanohybrid exhibits excellent electrical conductivity (1.84 × 104 Sm−1) and a higher BET surface area (147 m2 g−1). The Mn.Co3O4/r-GO sample electrode shows an outstanding electrochemical activity and exhibits a gravimetric capacitance up to 932 Fg−1 @ 1 Ag−1. On increasing the current density from 1 to 5 Ag−1, the nanohybrid electrode retains 84.4% of its original capacitance (at 1 Ag−1), indicating its excellent rate capability. Moreover, the nanohybrid electrode reveals exceptional cycling stability as it lost just 7.3% of its original capacitance (at the 1st cycle) after 5000-cycling experiments. The tremendous electrochemical activity of the fabricated nanohybrid can be ascribed to the synergistic effect between the good crystallinity of its Mn.Co3O4 NPs and excellent conductivity of its r-GO nanosheets. The 3D nanostructure of the Mn.Co3O4/r-GO nanohybrid decorated directly on the NF shorter the ion diffusion path and exposes more active sites to achieve the superior gravimetric capacitance and higher rate capability. This study may offer the use of multi-approaches to engineer the novel 3D nanostructured electrode materials for electrochemical capacitors with excellent cyclic stability, good rate capability, and higher gravimetric capacitance.

Recent Progress in Applications of Enzymatic Bioelectrocatalysis

Bioelectrocatalysis has become one of the most important research fields in electrochemistry and provided a firm base for the application of important technology in various bioelectrochemical devices, such as biosensors, biofuel cells, and biosupercapacitors. The understanding and technology of bioelectrocatalysis have greatly improved with the introduction of nanostructured electrode materials and protein-engineering methods over the last few decades. Recently, the electroenzymatic production of renewable energy resources and useful organic compounds (bioelectrosynthesis) has attracted worldwide attention. In this review, we summarize recent progress in the applications of enzymatic bioelectrocatalysis.

(Invited) Nanoarray Cathode Design for Durable Zn Batteries

Rechargeable aqueous zinc battery, as a novel promising candidate for grid-scale energy storage, has drawn tremendous attention recently. Our group has been actively working in design nanostructured electrode materials for metal-ion batteries (Na, K, Zn) and electrocatalysts for metal-air batteries. In this talk, I will present our latest results on cathode materials for both Zn-ion battery and Zn-air battery. Specifically, we developed layered ZnOV nanosheets that are directly grown on a 3D graphite current collector. Meanwhile, the anode is also 3D Zn nanosheet array obtained by electro-deposition. As for the Zn-air battery cathode, we employed 3D conductive MOF and Ni-based LDH hybrid materials on conductive carbon support as the electrode both for aqueous alkaline and all-solid-state Zn-battery. The whole material system has a high conductivity, sufficient active sites and low transition energy that render highly reversible redox reaction and inhibition of dendrite formation, as well as extremely soft feature so that it can be appropriate for the application of flexible devices. The all-solid-state Zn-based batteries using CMNC@CC and Zn@CC as the electrodes displays outstanding performance when compared with most of the aqueous oxy/hydroxy or pristine MOFs based energy storage devices.We appreciate the financial support from Agency for Science, Technology, and Research (A*STAR) by AME Individual Research Grant (A1983c0026) and from Singapore MOE AcRF Tier 2 Grant (MOE2017-T2-1-073).

Increasing Energy Density of Electrochemical Capacitors By Advanced Nanomanufacturing and Ionic Liquid Electrolyte

The growing number of energy consuming devices is driving an ever increasing demand for high efficiency, high capacity, and portable energy storage devices. In addition to higher levels of energy storage, there is a growing need for the capability to produce sustained high power pulses. For many applications, the energy storage devices must also provide a high cycle life to provide the sustained operation life, along with increased capability of providing high power over ever increasing pulse durations. Moreover, these energy storage devices are in demand over a wide range of sizes from chip-scale power storage to large-scale, kilovolt-level power delivery. Rechargeable batteries, in particular lithium ion, are well known and have been extensively developed for their high energy density, but their major drawback remains in their limited power density and cycle-life capability. Electrostatic capacitors, on the other hand, provide a high power density, and research has shown they have great potential for meeting the power and cycle life demands for the new energy storage device demands. However, for conventional electrostatic capacitors, the energy density and thus pulse power duration capability is very limited. Alternatively, electrochemically-based double-layer capacitors (EDLCs) or ultracapacitors, provide a pathway to an energy storage device that shows significant promise for delivering the high power density and high cycle life that is achievable with electrostatic capacitors, while providing a path to much greater energy storage and thus sustained long duration pulsed power delivery. Through the surface charge adsorption-based mechanism of energy storage utilized in EDLCs, it is possible to get high frequency response times while providing the ability to supply power for much longer periods of time than can be achieved with conventional capacitors. Despite this major benefit, currently available commercial EDLC devices still provide energy densities that are much lower than that of batteries. To increase the number of potential applications for EDLCs and displace batteries, the energy density must be increased. Thus the main focus of our ultracapacitor research, presented here, is increasing the energy density of ultracapacitors through the use of highly ordered nanostructured electrode materials, which are combined with a high voltage window ionic liquid-based electrolytes to increase the power and energy density.In EDLCs, the capacitance and corresponding energy storage capability are directly proportional to the electrode’s solution accessible surface area. To maximize this area, we have developed electrode structures with a tunable, highly controlled porosity that provides very high, electrolyte-accessible, surface area. We’ve developed a robust and scalable templated approach to allow the fabrication of high surface area carbon nanotube (CNT)-based electrodes with highly aligned and vertically-oriented CNTs. This approach provides an areal CNT density that is much greater than typical carpet-grown CNTs. Furthermore, through our templated fabrication approach, we can tune the electrode pore size, thus allowing us to optimize it for the specific electrolyte. Our approach, combining tuning of both the electrode and electrolyte, ensures maximum charge adsorption for energy storage, while maintaining excellent solution access for fast charge transport during charging and discharging, thereby ensuring power capability.Ionic liquids are becoming popular electrolytes for a range of applications because of their large voltage window, and chemical properties that can be tailored for the specific application. The use of ionic liquid electrolytes allows operation at higher cell voltages than the conventional aqueous or organic solution-based capacitors. Larger operation voltage further enhances the power and energy density in our capacitors. Additionally, since ionic liquids are nonflammable and have a negligible vapor pressure, they make the ideal electrolyte choice in higher temperature applications or for micro- and on-chip devices, where the removal of heat is difficult because of the confined space operating conditions. Through the use of designer electrolytes based on pure and mixed ionic liquids, and combining and optimizing the interaction of the electrolyte with our templated CNT electrodes, we are able to produce an energy storage technology which combines the optimal balance and benefits of high energy density and high-power density. This talk will detail our electrode development and device optimization efforts for our large format capacitors.[DISTRIBUTION STATEMENT A. Approved for public release; Distribution is unlimited 412TW-PA-20122]

Cryogenic Milling Method to Fabricate Nanostructured Anodes

Cryogenic milling was demonstrated as a new and facile method to fabricate nanostructured battery electrode materials. SnSb anode material with 1.2 wt % graphite was selected as a model system to d...

Hollow N-doped carbon @ O-vacancies NiCo2O4 nanocages with a built-in electric field as high-performance cathodes for hybrid supercapacitor

Delicate design of nanostructured electrode materials with built-in electric field effect can make them have satisfactory electrochemical performance through the synergistic effects. Here, we prepare an advanced electrode material, a hollow N-doped carbon@O-vacancies NiCo2O4 nanocage (HNC@NiCo2O4), in which NiCo2O4 nanosheets are homogeneously grown on the N-doped carbon frame. This unique hollow nanocage can increase the contact-area between the material and electrolyte, further improving the electrochemical activities. Density functional theory simulations reveal that O-vacancies in NiCo2O4 can narrow the bandgap, which may contribute to the charge transfer dynamic of HNC@NiCo2O4 series. Meanwhile, N-doping can change the carbon-skeleton states density, thereby improving the electron-accepting capabilities for nearby NiCo2O4, and thus elevating the capacitive behaviors. Accordingly, a built-in electric field is in-situ constructed via the O-vacancies and N-doping. Due to the synergistic effect of a hollow structure and built-in electric field, as-fabricated HNC@NiCo2O4-0.45 electrode delivers noticeable specific-capacitance (966.2 F g−1@1 A g−1) and long-term endurance. Impressively, the HNC@NiCo2O4-0.45 electrode is employed to assemble a hybrid supercapacitor with the active carbon anode, which behaves a high energy-density (41.9 Wh kg−1 at 750.4 W kg−1). Above results validate that the electric field modulation and nanostructure construction are important tactics to design a high-performance supercapacitor electrode.

Fabrication of Ni3S2 nanoneedle-sheets electrode material with ultrahigh areal capacity of over 15 mAh cm−2

Nanostructured electrode materials suffer low mass loading and areal capacity. In this work, large scale Ni3S2 nanoneedle-sheets array on foam Ni was fabricated via facile hydrothermal method, benefitting from the long size Ni3S2 nanoneedle and nanosheets secondary structure, this novel self-supporting Ni3S2 nanoneedle-sheets array possesses extraordinary reversible areal capacity of over 15 mAh cm−2 when applied as electrode for Lithium-ion batteries.

Facile soft chemical synthesis and characterisation of novel cobalt doped nickel oxide based nanostructured electrode materials for electrochemical capacitors

ABSTRACT Ni1-xCoxO1-δ (Where x = 0.01, 0.03, 0.05, 0.07, 0.09) (CNO) based nanostructured materials were synthesized by facile soft chemical route and characterised for application as electrodes in electrochemical supercapacitors. The prepared materials were studied by XRD, FITR, particle size, EDAX equipped with SEM, TEM and electrochemical studies such as CV, GCD and impedance analysis. XRD has confirmed the presence of the FCC crystalline structure. FTIR results have shown peaks at ~450 cm−1 which are relevant to metal oxide. The existence of nanosized particles were confirmed by particle size measurements. SEM analysis has further shown the appearance of spherical-shaped particles with average grain size ranging from 19.7 to 37.74 nm in the samples. The EDAX data has reflected the occurrence of appropriate elements as per stoichiometry calculations. The TEM analysis carried-out on Ni0.91Co0.09O1-δ has confirmed the presence of polycrystalline behaviour. Among the samples, Ni0.91Co0.09O1-δ electrode material has achieved more capacitance (338.13Fg−1).

Experimental investigation of Co and Fe-Doped CuO nanostructured electrode material for remarkable electrochemical performance

The current research work presents a facile and cost–effective co-precipitation method to prepare doped (Co & Fe) CuO and undoped CuO nanostructures without usage of any type of surfactant or capping agents. The structural analysis reveals monoclinic crystal structure of synthesized pure CuO and doped-CuO nanostructures. The effect of different morphologies on the performance of supercapacitors has been found in CV (cyclic voltammetry) and GCD (galvanic charge discharge) investigations. The specific capacitances have been obtained 156 (±5) Fg−1, 168(±5) Fg−1 and 186 (±5) Fg−1 for CuO, Co-doped CuO and Fe-doped CuO electrodes, respectively at scan rate of 5 mVs−1, while it is found to be 114 (±5) Fg−1, 136 (±5) Fg−1 and 170 (±5) Fg−1 for CuO, Co–CuO and Fe–CuO, respectively at 0.5 Ag-1 as calculated from the GCD. The super capacitive performance of the Fe–CuO nanorods is mainly attributed to the synergism that evolves between CuO and Fe metal ion. The Fe-doped CuO with its nanorods like morphology provides superior specific capacitance value and excellent cyclic stability among all studied nanostructured electrodes. Consequently, it motivates to the use of Fe-doped CuO nanostructures as electrode material in the next generation energy storage devices.

One pot synthesis and characterisation of two dimensional tin doped strontium oxide nanostructured electrode materials for electrochemical supercapacitor applications

ABSTRACT In this research work, we report a facile one pot synthesis of Sn doped SrO (Sr1-xSnxO1-δ; where x = 0.1, 0.2, 0.3 and 0.4) based two dimensional nanoparticles. The physico-chemical properties of the prepared materials were characterized by XRD, EDAX, SEM and TEM. XRD confirmed that the prepared samples are cubic. The presence of appropriate atomic percentage of elements was predicted by EDAX. SEM and TEM data confirmed the presence of nanostructured grains in the samples. The electrochemical techniques such as, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) were employed to characterize the reproducible performance of the Sn doped SrO nanostructured electrode materials in 1 M of H2SO4 medium. Among the different samples studied, Sr0.6Sn0.4O1-δshowed a maximum specific capacitance of 56.49 Fg-1 at a scan rate of 5 mV. Hence, Sn doped SrO can be good electrode material for electrochemical supercapacitor applications.

Facile and solvothermal synthesis of rationally designed mesoporous NiCoSe2 nanostructure and its improved lithium and sodium storage properties

Rechargeable metal ion batteries have attracted considerable attention in modern society because environmental issues are getting worse over time. They are highly expecting to play a vital role in day-to-day life in portable electronic devices (EVs) as well as hybrid electric vehicles (HEVs). Herein, we report the synthesis of bimetallic dichalcogenide by a solvothermal technique and systematically explore the effect of mesoporous NiCoSe2 (MNCS) nanostructures by controlling the ratio of surface-active agent during the synthesis process. The depth morphological evaluation using high-resolution field-emission transmission electron microscopy (HR FE-TEM) suggests that all the MNCS nanostructures display similar morphology with an extended network of material architecture when the ratio of surface active agent increased and thus interestingly play an important role in enhancement of surface area and porosity of the as-prepared electrode architecture. Interestingly, an obtained MNCS50 nanostructure displays a specific capacity of 557 and 398 mAh g−1 after 100 and 60 cycles for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), respectively. The larger surface area and high porous nature of MNCS50 nanostructure affords more spaces to accommodate larger numbers of lithium (Li) and sodium (Na) ions during the discharge/charge process, and the nanostructured electrode material often enhances the electrical conductivity. These observations are indicating the use of nanostructured anode materials for LIBs and SIBs.

Co3O4 Hollow Nanoparticles Embedded in Mesoporous Walls of Carbon Nanoboxes for Efficient Lithium Storage

AbstractConfining nanostructured electrode materials in porous carbon represents an effective strategy for improving the electrochemical performance of lithium‐ion batteries. Herein, we report the design and synthesis of hybrid hollow nanostructures composed of highly dispersed Co3O4 hollow nanoparticles (sub‐20 nm) embedded in the mesoporous walls of carbon nanoboxes (denoted as H‐Co3O4@MCNBs) as an anode material for lithium‐ion batteries. The facile metal–organic framework (MOF)‐engaged strategy for the synthesis of H‐Co3O4@MCNBs involves chemical etching‐coordination and subsequent two‐step annealing treatments. Owing to the unique structural merits including more active interfacial sites, effectively alleviated volume variation, good and stable electrical contact, and easy access of Li+ ions, the H‐Co3O4@MCNBs exhibit excellent lithium‐storage performance in terms of high specific capacity, excellent rate capability, and cycling stability.

Co3 O4 Hollow Nanoparticles Embedded in Mesoporous Walls of Carbon Nanoboxes for Efficient Lithium Storage.

Confining nanostructured electrode materials in porous carbon represents an effective strategy for improving the electrochemical performance of lithium-ion batteries. Herein, we report the design and synthesis of hybrid hollow nanostructures composed of highly dispersed Co3 O4 hollow nanoparticles (sub-20 nm) embedded in the mesoporous walls of carbon nanoboxes (denoted as H-Co3 O4 @MCNBs) as an anode material for lithium-ion batteries. The facile metal-organic framework (MOF)-engaged strategy for the synthesis of H-Co3 O4 @MCNBs involves chemical etching-coordination and subsequent two-step annealing treatments. Owing to the unique structural merits including more active interfacial sites, effectively alleviated volume variation, good and stable electrical contact, and easy access of Li+ ions, the H-Co3 O4 @MCNBs exhibit excellent lithium-storage performance in terms of high specific capacity, excellent rate capability, and cycling stability.

Nanostructured Electrode Materials for Rechargeable Lithium-Ion Batteries

Nanostructured Electrode Materials for Rechargeable Lithium-Ion Batteries

Synthesis of Cu-Doped Mn3O4@Mn-Doped CuO Nanostructured Electrode Materials by a Solution Process for High-Performance Electrochemical Pseudocapacitors.

Cu-doped Mn3O4 and Mn-doped CuO (CMO@MCO) mixed oxides with isolated phases together with pristine Mn3O4 (MO) and CuO (CO) have been synthesized by a simple solution process for applications in electrochemical supercapacitors. The crystallographic, spectroscopic, and morphological analyses revealed the formation of all of the materials with good crystallinity and purity with the creation of rhombohedral-shaped MO and CMO and a mixture of spherical and rod-shaped CO and MCO nanostructures. The ratio of CMO and MCO in the optimized CMO@MCO was 2:1 with the Cu and Mn dopants percentages of 12 and 15%, respectively. The MO-, CO-, and CMO@MCO-modified carbon cloth (CC) electrodes delivered the specific capacitance (Cs) values of 541.1, 706.7, and 997.2 F/g at 5 mV/s and 413.4, 480.5, and 561.1 F/g at 1.3 A/g, respectively. This enhanced Cs value of CMO@MCO with an energy density and a power density of 78.0 Wh/kg and 650.0 W/kg, respectively, could be attributed to the improvement of electrical conductivity induced by the dopants and the high percentage of oxygen vacancies. This corroborated to a decrease in the optical band gap and charge-transfer resistance (Rct) of CMO@MCO at the electrode/electrolyte interface compared to those of MO and CO. The net enhancement of the Faradaic contribution induced by the redox reaction of the dopant and improved surface area was also responsible for the better electrochemical performance of CMO@MCO. The CMO@MCO/CC electrode showed high electrochemical stability with a Cs loss of only ca. 4.7%. This research could open up new possibilities for the development of doped mixed oxides for high-performance supercapacitors.